New World Screwworm

“Report, Don’t Hide It”: Experts Urge Rapid Action When Suspecting New World Screwworm

Tue, 28 Apr 2026 21:14:04 GMT

As New World screwworm edges closer to the U.S., industry leaders urge producers to shift from worry to action.

Early detection, prompt reporting and treatment — backed by coordinated surveillance along the border — will be critical to keeping this treatable pest contained. Ranches are tightening calving seasons , upgrading working facilities and revisiting parasite control plans with their veterinarians. The core message to the fight against NWS: nothing replaces “eyes on animals.”

“We’ve been preparing for the possibility of screwworms emerging back in Texas for the past year,” says Jason Sawyer, East Foundation chief science officer. “We have decided to take the attitude of preparedness. We expect we’re going to have it. How can we best manage it and best mitigate and really, how do we minimize the impact while we weather the storm?”

The Breakthrough Symposium: NWS Preparedness panel (pictured l to r) are: Jason Sawyer, East Foundation; Dr. TR Lansford III, Texas Animal Health Commission; Dr. Diane Kitchen, Florida Department of Agriculture; Stephen Diebel, Texas beef producer and Texas & Southwestern Cattle Raisers Association president; and Dr. Megan Schmid, USDA-APHIS.

(Angie Stump Denton)

Sawyer participated in a panel during the The Breakthrough Symposium: NWS Preparedness, hosted by Merck Animal Health. The panelists didn’t debate whether NWS will arrive — they spoke as if it is already on the way. For producers, that means decisions must be made months in advance: adjusting breeding and calving windows to avoid peak risk, investing in better handling facilities and building a clear response plan with veterinarians. Combined with federal and state surveillance using fly traps, animal inspections and producer reports, these risk‑based steps can help ensure that when NWS appears, it is found fast, hit hard and kept from spreading.

With cattle markets at all‑time highs, panelists warn NWS must be managed in a way that protects both animal health and commerce. Movement controls, inspection and treatment protocols, and animal disease traceability are being designed to regionalize the problem — not shut the industry down.

Here are seven key takeaways from the panel discussion:

1. Prepare, Don’t Panic

New World Screwworm is a serious but manageable threat with proper planning and coordination.

“This isn’t a ‘sell the ranch and get out of business’ problem,” Sawyer summarizes. “This is a ‘let’s figure out the best way to move forward and minimize impact.’” Today’s challenge is to rebuild the “lost muscle memory” with modern tools and a risk‑based mindset. That means planning calving seasons with NWS risk in mind, enhancing parasite control without driving resistance and being ready to isolate, treat and recheck any affected animals in close coordination with veterinarians. The sooner producers start planning, the smaller and shorter the “storm” will be for everyone.

Some strategies producers should consider include:

Get a premise ID now, if you don’t have one.
Consider shifting calving and processing into lower‑fly windows.
Manage wounds differently . Any break in the skin — navels, castration, dehorning, tags and tick bites — becomes a high‑risk site once NWS is in the area.

Dr. Diane Kitchen, a cattle rancher and Florida Department of Agriculture veterinarian manager, bovine and cervidae programs, suggests producers consider using a preventative or at least a protectant to the area to minimize the chance of an infestation occurring.

Sawyer, who manages ranches near the U.S.-Mexico border, explains. “We’re trying to work with the weather instead of against it and think about comprehensive parasite control strategies that can minimize that risk for newborn calves, knowing that we’re unlikely to be able to put our hands on every one of them as they hit the ground.”

2. Eyes on Animals, Surveillance is Central.

Nothing replaces routine, disciplined visual checks — especially of newborns and any animal with a wound. Kitchen says preparation starts with understanding NWS targets wounds and certain high‑risk areas. The fly’s preference is umbilical cords, she stresses.

“It can also affect certain mucus membranes,” she explains. “The corners of the eye, the genital tract. In particular, cows that are calving, they’re attracted to the same umbilical cord scent.” External wounds can be tiny, internal damage massive. “The wound itself externally may be very small,” Kitchen says. “The size of a quarter. But then when you go to treat there may be gallons of maggots within underneath.”

Producers who have dealt with the pest often describe it as a smell you’ll never forget , noting that the stench of a calf infested with New World Screwworm is often the first warning sign.

Dr. Megan Schmid, USDA-APHIS Cattle Health Center assistant director, explains there are two types of surveillance:

Active surveillance: Fly traps along the border, border inspectors and Wildlife Services checking animals
Passive surveillance: Producers, vets, shelters and others seeing maggots/myiasis and reporting. “The traps are helpful,” she says. ”But they’re not as sensitive as the animal inspection. So really, that’s the key part: everybody looking for the infestations in animals.”

Producers can use technology to get more “eyeballs” on cattle and keep spread to a minimum. Game cameras, virtual fencing and behavior tags can help producers find problems sooner when labor is tight.

Because these infestations can be deceptive, producers should learn to identify the specific signs of New World Screwworm , such as unusual discharge or larvae deep within living tissue.

3. Report First, Don’t Hide It.

NWS is a reportable foreign animal disease. Early reporting is critical and legally required. Officials would rather investigate 1,000 false alarms than miss one real case.

Kitchen stresses failure to report will create many more flies.

“Failure to report results in multiple generations of additional flies, which just dramatically increases the population that’s available to impact everybody,” she explains. “If you think that because you didn’t report yours, that it’s not going to be found. It will be found because it’ll be found in something else.”

She encourages producers to think about the impact on their neighbor.

If the roles were reversed, she asks, “If you hear that somebody, your neighbor, is one that didn’t report, how happy are you going to be with them?”

4. Vet Relationships Are Essential.

A veterinarian is central to preparation and treatment plan. For wound care, antibiotics, pain management and access to tools, a veterinary client–patient relationship is vital. Treatment is about parasite removal and wound management, guided by vets.

Panel members explain part of being prepared is sitting down now with your veterinarian and discussing: “If we get screwworm, what’s our plan? How often are we looking at cattle, what products are we going to use, and what do we do about movements?”

Read more about how NWS is an infestation, not an infection.

5. Wildlife Matters in This Fight.

Wildlife are a major reservoir and economic driver, and can suffer large population impacts without control. Kitchen predicts in infested areas 70% to 80% of white-tailed fawn crops could be lost.

“Our wildlife populations are both so much more abundant than they were in the 1950s and so much more valuable than they were in the 1950s,” Sawyer says. “Unfortunately, the opportunity to intervene for wildlife is much smaller. There’s really not very many strategies that are viable, and so surveillance and monitoring become really our front line of defense in terms of our wildlife populations.”

He suggests the best way to protect wildlife is aggressive control in livestock to reduce environmental burden.

6. Quarantines Are Tools, Not Punishments.

The goal is continuity of business with safeguards , not shutting down commerce. Regulators are trying to balance containment with commerce. The goal is to maintain the “speed of commerce” while using structured movement protocols to protect markets and disease-free areas.

“It’s not going to be business as usual, but it’s going to be business is still possible,” Schmid says. “The focus is: how do we allow safe movements, not restrict and stop business.”

She says the New World Screwworm Response Playbook includes guidance documents and explains the quarantine/movement framework.

Stephen Diebel, Texas beef producer and Texas & Southwestern Cattle Raisers Association president, encourages producers not to think in terms of a hard quarantine. A structured process of treatment, surveillance, inspection and certification will allow movement.

Dr. TR Lansford III, Texas Animal Health Commission assistant state veterinarian and deputy executive director, encourages producers to reference the lessons learned from fever ticks as a strategy for dealing with NWS. He notes experience with fever ticks has shaped how Texans think about area quarantines, treatment protocols and continuity of business.

7. More Tools in the Toolbox.

Panelist members summarize a holistic ectoparasite program using modern products plus strong producer education is a main NWS defense strategy.

Kitchen stress producers and veterinarians have many more tools than they did back in the ’60s and ’70s when NWS was last endemic in the U.S.

Producers can find a list of approved treatment and prevention strategies on the FDA website .

Sawyer suggests producers work with their veterinarians to plan prevention and treatment strategies. He also stresses the importance of considering resistance management.

“We don’t want to react to an emergent threat in a way that then creates problems with a persistent pest that’s already present,” he says.

Read More About How Sterile Flies are the No. 1 Tool to Fight NWS:
Doubling the Defense: USDA’s “Male-Only” Fly Breakthrough to Transform Screwworm Eradication
Border Remains Closed: Sterile Fly Production Facility Groundbreaking Next Step in Screwworm Fight

While NWS is a serious and emotionally charged threat, panelists remind producers the U.S. has pushed it back before — and can do it again.

“This pest existed here before, and it has been eradicated from the U.S. before,” Sawyer summarizes. “We know how to do it. We just have to sort of build the capacity and muscle to get it done again when we need to.”

From the Parlor to the Perimeter: Protecting the Heart of American Dairy in 2026

Fri, 24 Apr 2026 14:28:22 GMT

2026 marks a defining moment for U.S. dairy producers. As biological threats evolve and new risks loom on the horizon, the industry’s focus has moved from the parlor to the perimeter. During a high-level panel at the High Plains Dairy Conference, leaders including Jason Lombard, Samantha Holeck and Dee Ellis addressed the biosecurity gap and the urgent need for a line of separation to safeguard the milk supply. This isn’t just a discussion about animal health; it’s a strategic deep dive into the risk management and business continuity required to keep the American dairy industry moving forward in a volatile world.

The Ghost in the Mammary Gland: The H5N1 Legacy

Lombard opened the discussion with a sobering retrospective on H5N1. What began as a bird flu headline in December 2021 has evolved into a complex, multi-species challenge that has fundamentally altered the dairy landscape.

Lombard’s timeline showed the relentless march of the virus. From the first detections in wild birds in the Carolinas to the jump into commercial turkeys in 2022, the industry watched with wary eyes. But 2024 was the year the ground shifted. The B3.13 genotype emerged in dairy cattle in Texas and Kansas, eventually spreading to multiple states and even jumping to alpacas and swine. By late 2025, new genotypes like D1.1 were being detected in Arizona, Nevada and Wisconsin.

The most jarring revelation, however, was the visual evidence of where the virus hides. Lombard shared microscopic images of the mammary gland, where sialic acid receptors — the locks the virus keys into — glowed red, and the virus itself (AIV) glowed yellow.

“It’s in the milk,” Lombard stated flatly.

The spread isn’t just about a bird dropping a feather in a feed bunk. The data now shows a web of transmission: the movement of cattle, the movement of people and even the breathing of the herd. Most concerning for the 2026 outlook is the role of aerosols and peridomestic birds like swallows, pigeons and starlings. We are fighting a ghost that can be carried on a breeze or the back of a common filth fly.

The Emerging Nightmare: New World Screwworm

While the industry is still reeling from H5N1, Holeck introduced a threat that sounds like the plot of a horror movie but carries devastating economic reality: New World screwworm (NWS).

For decades, the U.S. has been protected by the “Darien Gap” and a massive eradication effort that pushed the screwworm south into Central America. But in 2026, the map is changing. Holeck shared a situational update showing thousands of active cases in Mexico, with some pushing dangerously close to the U.S. border.

“This will change the way we do business,” Holeck warned.

If NWS crosses the border, the implications are immediate and severe. We are talking about total movement restrictions, intensive live-animal inspections and the potential for lost trade. Unlike a virus, NWS is a parasite — a fly that lays eggs in open wounds, where larvae then consume living tissue. Holeck’s toolbox for 2026 isn’t just about vaccinations; it’s about management. It’s about preventing injuries, adjusting management practices to keep wounds clean, and a hyper-vigilant remove and dispose protocol for larvae.

The Reality of the Gap: Data from the Barn Floor

Farm Journal conducted its own research on research launched at the 2025 Milk Business Conference. The research illustrates a significant biosecurity gap between large and small operations.

The data showed that while 71% of producers have cameras in their milking parlors, only 38% have defined entrances with clear signage for designated vehicles like milk and feed trucks. The discrepancy becomes even sharper when looking at herd size. Larger dairies are significantly more likely to have designated employee parking (+23%) and cameras at facility entrances (+32%) compared to dairies with fewer than 1,000 cows.

The producer’s dilemma is real: ROI versus risk. On a smaller operation, a $20,000 security and sanitation upgrade can feel like a mountain, especially when the threat hasn’t hit your zip code yet. But as the panel emphasized, biosecurity is like insurance — you only realize its value when it’s too late.

One of the most telling statistics from the survey was that 25% of producers admitted they “don’t control and limit access” to feed storage areas. In an era where H5N1 and other diseases can be carried by wildlife and birds into the very food the cows eat, this is a glaring vulnerability.

The Blueprint: Drawing the Line of Separation

Ellis provided the how-to for the future: The Secure Milk Supply (SMS) Plan. This isn’t just a binder that sits on a shelf; it is a voluntary, science-based framework designed to ensure business continuity during a disease outbreak.

The core of the SMS plan is the line of separation (LOS). Ellis shared sample dairy maps that looked more like tactical military charts than farm layouts. The LOS creates a clear clean/dirty boundary.

The Dirty Side: Where public roads, non-essential deliveries and rendering trucks reside.
The Clean Side: The protected area where cows live, eat and are milked.

Implementing an SMS plan means identifying specific LOS access points, creating vehicle cleaning and disinfecting stations and establishing strict logs for every person and animal that crosses that line.

“Don’t sacrifice good for perfect,” Ellis advised. “Every SMS plan is unique. The key is to start. Post your map where every employee can see it every day. Make the clean/dirty concept part of your farm’s culture.”

The Biosecurity Umbrella

Biosecurity can feel like a cloud of acronyms and diseases: BVD, TB, Johne’s, Mycoplasma and now H5N1 and NWS.

Biosecurity isn’t easy. It’s tedious. It’s expensive. And it’s often invisible.

As an industry, we must move away from a reactive posture and toward a proactive, fortified model of production. Whether it’s a million-dollar operation in the Texas Panhandle or a 100-cow family farm in Wisconsin, the line of separation is the same.

The call to action for the industry is the same for every operation across the U.S.:

Assemble your team and review protocols now — before the challenge hits.
Look at your perimeter and sanitation, especially in feed and transport areas.
Support each other. If you serve producers, help them find the resources to make these investments.

While we may be facing genotypes and parasites that generations before us never dreamed of, we now have the science, the data and the collective will to protect the milk supply.

The 2026 revolution isn’t just about how much milk we can produce; it’s about how well we can protect it. And in that mission, we are all behind the wheel together.

USDA’s "Male-Only" Fly Breakthrough to Transform Screwworm Eradication

Fri, 10 Apr 2026 15:27:41 GMT

USDA’s Agricultural Research Service (ARS) is advancing the next evolution of the long-trusted sterile insect technique (SIT) to protect U.S. livestock from New World screwworm (NWS) by introducing a 100% male-only sterile fly strain. This breakthrough will effectively double the production capacity of sterile fly facilities without expanding physical infrastructure. By eliminating the production of “useless” female flies, the USDA-ARS innovation aims to push the NWS fly further south, providing a more robust and cost-effective defense for American livestock producers.

A USDA spokesperson explains, “USDA is using gold standard, proven scientific methods to manufacture NWS flies to produce only male flies and increase the efficiency of SIT. USDA is simply making a proven tool even more efficient and effective to better protect America’s farmers and ranchers.”

USDA currently produces sterile flies for dispersal at the COPEG facility in Panama. USDA is also investing $21 million to support Mexico’s renovation of an existing fruit fly facility in Metapa — which will double NWS production capacity once complete.

Moore Air Base: On Time and On Budget for 2026 Production

Dudley Hoskins, USDA under secretary for marketing and regulatory programs, was a guest Tuesday on AgriTalk. He discussed sterile fly dispersal efforts.

“We’re doing two things,” he says. “One, the Secretary has us modernizing our infrastructure and our production capacity. She has us working on Moore Air Base, which will be a sterile fly production facility, that when it’s finally complete and at max-capacity production, will be producing about 300 million sterile flies per week. ”

Deputy Secretary Stephen Vaden recently reported USDA is on track and on time with regard to the Moore Air Base facility near Edinburg, Texas.

The Science of Stopping the Spread: Why Male-Only Matters

SIT, when paired with surveillance, movement restrictions and education and outreach, is an effective tool for controlling and eradicating NWS. Female NWS flies only mate once in their lives, so if they mate with a sterile male, they lay unfertilized eggs that don’t hatch. Releasing sterile flies just outside of affected areas helps ensure flies traveling to new areas will only encounter sterile mates and will not be able to reproduce.

Hoskins says concurrent to the process at Moore Air Base, USDA is working with its partners at the ARS and Environmental Protection Agency (EPA) to evaluate the genetically-engineered fly — the NovoFly — which would help get more male flies in the sterile fly production facility.

Vaden calls the possibility exciting.

“Basically we’ve been losing half of the production at every facility because what we need are sterile male flies, but of course with nature, half of what you get are female flies, and those to this particular enterprise are useless,” he explains. “Thanks to our agricultural research service, we now have the ability to pump out 100% sterile male flies only, no wastage. That has the effect of doubling production without any change in the available facilities.“

He adds, “We expect to be able, once EPA approves that innovation is safe later this year, to have all those facilities, including the one under construction at Moore Air Base, pumping out 100% sterile male flies, which will make our ability to push this pest back further south where it belongs to take root and begin to have great effect. Not just to hold it, but to push it further south.”

Hoskins summarizes, “All of those things are in motion, all things happening concurrently, and all those will be critical in modernizing our toolbox to take the fight to the screwworm.”

Listen to the conversation on AgriTalk :

Regulatory Road Map: The EPA Public Comment Period

USDA is following established regulatory pathways and submitted to EPA an Emergency Use Exemption and Application for Registration. EPA published the notice of receipt and request for comments in the Federal Register on March 27 and is accepting public comments until April 27 before making a determination.

According to the notice, the application from USDA states: “To register a new pesticide product containing an unregistered pesticide, NovoFly male-only genetically engineered (GE) New World screwworm (NWS) in USDA’s Sterile Insect Technique (SIT) programs. Additionally, the Agency received a Section 18 quarantine emergency exemption application requesting use of the same pesticide to maintain broad suppression of and help prevent the pest from moving further northward from Mexico toward the United States.”

EPA is providing the notice in accordance with the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA).

The notice says, “Due to the urgent nature of the emergency, the limited time available to authorize the Section 18 quarantine emergency exemption request and the related FIFRA Section 3 product registration application under review for the same use, EPA is waiving the comment period associated with the emergency exemption request but is soliciting public comment in conjunction with the application for Section 3 product registration of NovoFly.”

To make comments or learn more, visit the EPA website .

Read more about sterile flies and current distribution:

USDA Updates New World Screwworm Response Playbook for Ranchers and Vets

Thu, 09 Apr 2026 12:40:45 GMT

The “ New World Screwworm Response Playbook” was developed as a resource to help animal health officials and responders manage and adapt their response if NWS is found in the U.S. The first draft of the Playbook was released in October 2025.

U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) released an updated Playbook to serve as a comprehensive guide to support coordinated, science-based action should NWS be detected.

“USDA continues to execute Secretary Rollins’ five-pronged plan to keep NWS out of the United States,” says Dudley Hoskins, USDA under secretary for marketing and regulatory programs. “While we are aggressively safeguarding American agriculture and working with Mexico to prevent further northward spread, we must also ensure that our domestic response plans are ready for immediate activation. Strong coordination with states, producers, veterinarians, sportsmen and other partners is essential to achieving that goal.”

Hoskins was a guest Tuesday on AgriTalk. He discussed NWS preventative and response measures, including the sterile fly dispersal efforts.

He explains the goal of the Playbook is to try to balance that constant posture of vigilance, prevention and emergency response coordination.

“We want to be as least disruptive to the industry and commerce as possible,” he explains.

Hoskins stresses APHIS is asking for feedback on version two of the Playbook as they continue to fine-tune the response plan.

“We’re asking that same community of states and industry partners to continue to review the playbook,” he explains. “We want to continue to have those discussions and and those deliberations to improve the can and hopefully perfect have to use it, and hopefully never have to use it.”

Refining the Rules: Key Updates to the 2026 Playbook

The updated Playbook outlines critical science-based strategies for federal, state, tribal and local responders, including how to:

Coordinate response operations
Reduce spread and prevent establishment of NWS in new areas
Manage the pest in infested animals
Implement NWS fly surveillance and control measures
Maintain continuity of business
Support efficient information flow and situational awareness

APHIS has released the updated New World Screwworm Response Playbook - strengthening preparedness via coordination with states, producers, veterinarians, wildlife & other partners.🤝
It guides rapid, science-based action should NWS be detected in the U.S.https://t.co/lgplvaNjDy pic.twitter.com/kq4wKbqkGY
— USDA Animal and Plant Health Inspection Service (@USDA_APHIS) April 8, 2026

Collaborative Design: Incorporating Tribal and Industry Expertise

After sharing the draft Playbook in October 2025, APHIS worked to gather feedback from state animal health officials, federal partners, livestock and wildlife industry groups, tribal partners, veterinary organizations and other key stakeholders to prepare the updated version.

According to the APHIS press release , “Their expertise and operational experience were essential in shaping practical, field-ready guidance for real-world response scenarios.”

Based on this feedback, APHIS made several key updates to the Playbook including clarifying and expanding:

Terminology — NWS establishment, suspect, zones, types, phases, quarantines — treatment versus preventative NWS animal drugs and pesticide products
Agency roles, responsibilities and authorities
Animal movement requirements
Wildlife management, including:
- Improved description of roles, responsibilities and authorities related to wildlife
- Added and improved definitions of confined, farmed, and free-ranging wildlife
- Refined guidance on use of antiparasitic drugs and pesticide for use on/in wildlife
- Development guidance on wildlife surveillance

Accessing the Playbook: Resources for Producers and Responders

APHIS updated four supplemental guidance documents that were posted with the draft Playbook and added an additional eight supplemental guidance documents, all referenced in the Playbook .

(USDA APHIS NWS Playbook)

“To ensure continued alignment with state-level plans and industry practices, APHIS will continue to revise the Playbook as preparedness activities advance and evolve,” the release explains. “The agency will continue to work directly with states, territories, tribes, federal agencies, industry wildlife and other partners to refine response tools, strengthen coordination and support joint planning efforts.”

Your Next Reads:

How Will U.S. Producers Maintain Business when New World Screwworm Invades?

Wed, 11 Mar 2026 19:59:32 GMT

With animal disease, prevention and preparation beat panic. Since New World screwworm (NWS) was last eradicated from the U.S. in the 1960s, the tools and infrastructure to deal with foreign animal disease have dramatically changed.

Dr. Justin Smith, Kansas animal health commissioner and state veterinarian, during the recent Kansas State University Cattlemen’s Day gave an update on how Kansas and other states are preparing for NWS. The approach is designed to keep producers in business, keep cattle and products moving, and manage NWS in a way that protects both herds and markets.

He says the U.S. animal health officials along with USDA are planning a multistate, coordinated response that aims for consistency across state borders.

Smith summarizes the industry’s preparation to tackle NWS is like a three-legged stool. U.S. producers will be able to maintain business when NWS invades through surveillance, treatment and movement controls.

Surveillance: Eyes on Animals

The first leg of the stool is surveillance. He stresses early detection depends heavily on producers and veterinarians watching animals closely and reporting anything suspicious.

Smith emphasizes they would rather over investigate than miss a case.

“We want to make sure that we err on the side of having to say no on many occasions, versus saying, ‘Yep, this is what we got.’ Eyes on animals is going to be key.”

He was clear this should feel like partnership, not policing.

“They don’t want it to look like Big Brother coming over your shoulder,” he explains. “I hope we want to get this thing quickly.”

Smith explains that once a positive premises is identified, surveillance becomes structured around zones. The infested premises sit at the center, surrounded by an infested zone, an adjacent surveillance zone and a broader fly surveillance area.

The infested zone is 12.4 miles in radius from the infested premises. In this zone, there will be frequent on‑animal checks for wounds and larvae, plus enhanced monitoring in surrounding zones using fly traps and animal observation. The adjacent surveillance zone is another 12.4 miles radius and then there will be a fly surveillance area — an 124-mile radius from the infested premises.

Smith says movements out of the infested zone will require visual inspection for wounds and systemic treatment, including a treatment window of three to 14 days before movement plus a documented certificate of veterinary inspection.

He says the current Kansas response plan aligns with USDA’s playbook and neighboring states’ plans while taking into account specific needs of the Kansas livestock industry.

He stresses the playbook will continue to evolve, and state-by-state implementation may vary, but he says the “zone approach” will be utilized by all states.

Treatment: Limited Tools, Use Strategically

The second leg is treatment. Smith says that after decades without large domestic outbreaks, labeled options are limited.

From the fact that we haven’t had this new tool in our nation, in a large-spread outbreak since the 60s, we don’t have a lot of treatments out there that are labeled for this organism.”

To date, the Food and Drug Administration (FDA) has approved four products for large animals:

He cautions, “The goal is not to go out there and just habitually treat your animals just in case. We want to make sure that we’re utilizing these [products] responsibly. There’s not an unlimited supply out there, and so we want to make sure that it’s available for us when we do need it.”

On a positive premises, Smith says treatment will be mandatory and systematic.

“There will be a quarantine placed on that premises. We’re also going to require a certain level of treatment on that premises,” he explains.

There will be protocols for daily mortality disposal, so carcasses don’t become breeding sites.

“The last thing you want to do is bury an animal that has larvae and has the ability to advance.”

He says treatment is also tied to movement out of infested zones, with most animals needing prophylactic treatment before leaving.

Movement Controls: Targeted, Not Statewide Shutdowns

The third leg is movement control, designed to be precise rather than broad-brush. Smith stresses NWS is an infestation, not an infection , emphasizing it is not a systemic disease problem, but an infestation that still demands strong controls.

He says there will be movement restrictions if a premises falls into an infested region. To move animals out of that zone, there will be steps to follow but movement will not be completely shut down.

He explains some exceptions exist:

Animals moving directly to slaughter can go without pre‑movement treatment, but those animals have to be hanging on the rail within 72 hours.
Baby dairy calves must be treated but can move right away if treatment and navel care are documented.

He says Kansas is also coordinating with neighboring states to create “synergistic” rules, especially for cattle from higher‑risk states such as Texas. Cattle entering Kansas from recognized infested zones will face inspection, treatment requirements and at least 14 days in drylot containment on arrival.

NWS is Not a Food Safety Issue

Smith reassures producers and consumers that NWS is not a meat safety threat.

“This is not a food safety issue,” he says. “If an animal is presented to slaughter, it has a screwworm wound then it has the ability to be trimmed. That carcass will not be condemned. There are no restrictions on any inspected product for food safety reasons.”

Smith summarizes underpinning all three legs is a commitment to dynamic planning and continuity. He notes a revised USDA playbook is forthcoming and that “plans will be a little bit dynamic” as they learn more.

The core message for producers is clear: watch your cattle, report early, use treatments wisely and expect targeted movement controls — not blanket shutdowns — if NWS crosses the border.

USDA Announces Sterile Fly Production Facility Construction Contract

USDA and U.S. Army Corps of Engineers (USACE) announced March 9 a construction contract with Mortenson Construction to build a new sterile fly production facility at Moore Air Base in Edinburg, Texas.

This facility is a key component in U.S. Secretary of Agriculture Brooke Rollins’ sweeping 5-prong strategy to fight NWS. USACE is partnering with USDA and will provide oversight for the contract, design, engineering and construction of the facility.

“The Army Corps of Engineers is an essential partner in bringing this facility to life and further highlights the Trump Administration’s government-wide effort to fight the New World Screwworm threat in Mexico,” Rollins says. “The Army Corps is the best in the business and their engineering expertise and proven track record in delivering complex projects will help ensure we can build a modern, resilient facility that protects American agriculture from invasive pests for decades to come. This first-of-its-kind facility on U.S. soil will ensure we are not reliant on other countries for sterile flies.”

A sterile fly production facility is a specialized biosecure complex where NWS flies are raised and sterilized using irradiation and then released into targeted areas.

USDA currently produces about 100 million sterile flies per week at the COPEG facility in Panama and disperses them within and just north of affected areas in Mexico. In addition to the COPEG facility in Panama, USDA invested $21 million to support Mexico’s renovation of an existing fruit fly facility in Metapa , which will double NWS production capacity once complete.

With ongoing support from APHIS technical experts, Mexico anticipates sterile fly production will begin at this facility in summer 2026. The new facility at Moore Air Base will be the only U.S.-based sterile fly production facility and will work in tandem with facilities in Panama and Mexico to help eradicate the pest and protect American agriculture.

USDA and USACE will break ground on this new facility later this spring, after initial planning and development meetings with the new contractor. By November 2027, the production facility at Moore Air Base is expected to reach its initial goal of producing 100 million sterile flies per week. After that, construction will continue at the facility to increase production with the long-term goal of producing 300 million sterile flies per week.

F10 Antiseptic Wound Spray with Insecticide Approved to Prevent and Treat New World Screwworm

Wed, 11 Mar 2026 13:17:47 GMT

The U.S. Food and Drug Administration has issued an Emergency Use Authorization (EUA) for F10 Antiseptic Wound Spray with Insecticide (benzalkonium chloride, polyhexanide and cypermethrin topical solution) for the prevention and treatment of New World screwworm (NWS) infestations (myiasis).

The FDA has concluded that based on the scientific evidence available, it is reasonable to believe that F10 Antiseptic Wound Spray with Insecticide may be effective in the prevention and treatment of NWS myiasis in cattle, horses, minor species of hoof stock (sheep, goats, deer), raptors and other wild birds, pet birds, and captive wild, exotic and zoo mammals. The known and potential benefits of the product outweigh its known and potential risks.

F10 Antiseptic Wound Spray with Insecticide may not be used in domestic dogs and cats.

To date, the FDA has conditionally approved or issued EUAs for drugs to prevent and/or treat NWS in cattle, dogs and cats. F10 Antiseptic Wound Spray with Insecticide is the first product authorized by the FDA for NWS indications in additional species.

The agency evaluated relevant human food safety information and concluded that the food products obtained from treated animals are safe for human consumption when the terms and conditions of use granted by the EUA are followed, including the withdrawal period and milk discard time.

Important food safety information:

Cattle, goats, and sheep must not be slaughtered for human consumption within 30 days of treatment.
For non-domesticated minor species of hoof stock (e.g., deer, elk, antelope and nilgai), use only when there is a reasonable certainty that the treated animal will not be slaughtered or harvested for human consumption within 30 days of treatment.
Milk taken from cows, goats, or sheep during treatment and for 10 days after treatment must not be used for human consumption.
A withdrawal period has not been established for this product in pre-ruminating calves. Treated calves and calves born to treated cows must not be processed for veal.

Detailed product information about F10 Antiseptic Wound Spray with Insecticide can be found in the Fact Sheet: Emergency Use Authorization of F10 Antiseptic Wound Spray with Insecticide (benzalkonium chloride, polyhexanide and cypermethrin topical solution) for New World screwworm (NWS) .

F10 Antiseptic Wound Spray with Insecticide is available over the counter without a prescription. F10 Antiseptic Wound Spray with Insecticide is sponsored by Health and Hygiene (Pty) Ltd , based in South Africa.

Your Next Reads:
New World Screwworm: An Infestation, Not Infection
The Smell You’ll Never Forget: A Calf Infested with New World Screwworm

FDA Approves IVOMEC to Help Protect Cattle Against New World Screwworm

Thu, 05 Feb 2026 23:50:15 GMT

The Food and Drug Administration (FDA) has issued an emergency use authorization (EUA) for the use of IVOMEC(ivermectin) 1% Injection for the prevention of infestations caused by New World screwworm (NWS) in cattle.

“Protecting the health and well‑being of livestock is at the core of our mission,” says Steve Boren, Boehringer Ingelheim vice president of U.S. Livestock. “Emergency Use Authorization for IVOMEC (ivermectin) 1% Injection provides cattle producers and veterinarians with an important preventive tool against New World screwworm. We appreciate the proactive approach of the FDA and USDA in response to this emerging animal health threat and remain dedicated to supporting veterinarians, producers, and government as we work together to protect cattle herds.”

Under the EUA, IVOMEC (ivermectin) 1% Injection is authorized for the prevention of infestations caused by NWS (Cochliomyia hominivorax) larvae (myiasis) when administered within 24 hours of birth, at the time of castration, or at the appearance of a wound in cattle, except for female dairy cattle producing milk for human consumption and calves that will be processed for veal.

“Having worked in regions where New World screwworm is endemic, I’ve seen firsthand that effective readiness depends on access to preventive tools and strong producer education,” says Dr. Gustavo Sabatini, Boehringer Ingelheim global technical manager for ruminant parasiticides, who recently testified before the Texas House Agriculture and Livestock Committee on NWS preparedness alongside federal and state animal health officials and industry groups. “Screwworm strikes cattle when they are most vulnerable, including at birth, and demands more labor‑intensive management on the ground. That’s why prevention is essential – not only to protect animal health, but also to safeguard the food supply and the livelihoods of cattle producers.”

Based on available scientific evidence, FDA determined that there is no adequate, approved, and available alternative to the product for the prevention of NWS in certain cattle at these critical intervention points.This is the first EUA for any over-the-counter drug for the prevention of infestations caused by NWS in cattle, providing timely access to a preventive tool should an NWS incursion occur in the U.S.

Your Next Read: New World Screwworm: An Infestation, Not Infection

New World Screwworm: An Infestation, Not Infection

Wed, 04 Feb 2026 22:55:33 GMT

New World Screwworm (NWS) is an infestation of individual animals, not a herdwide infection like many diseases. Finding one infested animal does not automatically mean the whole herd is infested.

“This is not infection,” explains Adis Dijab, DVM and veterinary services associate deputy administrator for USDA’s Animal and Plant Health Inspection Service (APHIS). “When you talk about infection, there is a potential that every single animal is infected. In this case, it’s [the] infestation of one animal; you can check the rest of your animals and they can be fine.”

What does this mean for operations? If NWS does cross the border, quarantine and movement controls will be designed to inspect and treat affected animals. Dijab says this means producers can clear the rest of the herd as quickly as possible, and there will be a pathway to continue business, not a blanket, long‑term stop on all movement — assuming cooperation and inspections.

APHIS will try to avoid blanket shutdowns by targeted zoning and quick pathways out of quarantine after inspection and treatment.

Dijab gave a NWS update during the cattle health and well-being committee at CattleCon. Here are four key points from his presentation:

1. What NWS is and why it’s dangerous

NWS is a parasitic fly whose larvae require living tissue to feed.
Its life cycle is 21 days but can be longer in colder climates.
The fly is not active around 40°F.
NWS flies prefer water, shade greenery and hosts.
They typically move only about 3 km (approximately 1.6–1.7 miles) per day if they must; they are not strong long‑distance flyers.

Dijab shares the top 10 conditions leading to myiasis in Mexico, with umbilical being No. 1.

(Data source: COPEG)

2. Current NWS Spread Pattern in Mexico Strongly Suggests Illegal Movement of Animals, Not Just Fly Movement

“One of the primary modes of movement of this fly is not flying of the fly; it’s a set of 18 wheels doing probably 60 or 70 [mph] down the road,” Dijab says. “Southern Veracruz had a pretty healthy number of the cases. Then suddenly it jumped into the middle of Tamaulipas, which clearly showed there was illegal movement.”

Due to this concern, USDA took the proactive action to start dispersing sterile flies in the southeast corner of Texas as well.

3. Sterile Insect Technique Is Key

The U.S. has long relied on sterile insect release as its primary eradication tool.
Panama facility (COPECA) currently produces approximately 100 million sterile pupae a week.
“This is what’s keeping us alive right now,” Dijab says. “This is the reason that we don’t have a New World Screwworm on the U.S. soil.”
A new U.S. facility is planned at Moore Air Base in South Texas. Dijab says the construction award is targeted for March/April, with an operational goal of 300-million sterile flies a week by 2027. He adds they expect a six-to-eight-month ramp‑up.
The U.S. is collaborating with Mexico in remodeling a fruit-fly facility in Metapa, Chiapas. The U.S. is investing approximately $21 million. The goal is 100 million sterile flies a week, with first output expected late summer.
The combined goal is approximately 500 million sterile flies a week, similar to volumes used in the 1990s’ eradication to the Darién Gap.

Dijab summarizes that APHIS is rebuilding and expanding sterile fly capacity to historical eradication levels, which is essential for long‑term regional control and eventual border reopening.

4. The U.S. is Using a Layered Defense: Strict Import Controls, Active Surveillance and Border Trapping to Detect Any Incursion Early

The two main surveillance streams are:

The Foreign Animal Disease Diagnostician (FADD) network of 400 trained federal and state veterinarians.
Trap lines along the U.S.-Mexico border, placed near water, livestock and greenery.

Dijab says that, since June, there have been more than 300 FAD NWS investigations, with zero findings so far and more than 900 hide/wildlife inspections. He adds that what scares him the most regarding NWS is wildlife.

Read More: The Importance of Wildlife Monitoring for New World Screwworm

U.S. Begins Dropping Sterile Flies in Texas to Stop Screwworm

Mon, 02 Feb 2026 12:48:45 GMT

New World screwworm (NWS) is inching closer to the U.S. Last week Mexico reported eight new cases in the U.S. neighboring-state of Tamaulipas. A key to slowing down the threat is being proactive.

U.S. Department of Agriculture’s (USDA) import requirements and protocols are one line of defense for NWS and other foreign animal diseases that threaten U.S. livestock. According to USDA , earlier this week, a horse from Argentina was presented for routine importation at an equine import quarantine facility in Florida.

“Upon examination, APHIS identified an open wound with larvae on the animal and promptly collected and shipped samples to the National Veterinary Services Laboratories (NVSL) in Iowa. The horse was immediately treated with medication to kill any larvae in accordance with standard, long-standing import protocols.” the release explains . “This morning, NVSL confirmed that the larvae were NWS larvae. Accordingly, the animal will remain in quarantine until it has been reexamined and determined to be free of NWS.”

This is an example of import protocols working as designed. While this situation does not appear to be associated with the NWS outbreak in Mexico, the release says it underscores the need for vigilance in all of USDA’s coordinated efforts to fight NWS.

New Action To Prevent Northward Spread

Friday, Jan. 30, USDA’s Animal and Plant Health Inspection Service (APHIS) announced a shift in its 100-million-per-week sterile fly dispersal efforts .

“USDA will reallocate aircraft and sterile insects to reinforce coverage along the U.S.-Mexico border,” according to the release. “The new dispersal area, or polygon, will include operations about 50 miles into Texas, along the U.S. border with the state of Tamaulipas, Mexico. Mass production and targeted dispersal of sterile insects are critical components of an effective strategy to fight NWS. Other tools including import protocols and surveillance continue to support these robust efforts to keep NWS out of the U.S.”

Dudley Hoskins, USDA undersecretary of marketing and regulatory programs, says, “At Secretary Rollins’ direction, our highest priority is protecting the United States from screwworm. The northernmost active case of NWS in Mexico is still about 200 miles away from the border, but we’ve seen cases continue to spread in Tamaulipas and further south in Mexico, so we are proactively shifting our polygon as we make every effort to prevent NWS from reaching our border.”

This follows Texas Gov. Greg Abbott’s actions on Thursday issuing a statewide disaster declaration to better equip the Texas NWS Response Team to prevent the potential spread of the NWS fly into Texas and to better protect livestock and wildlife.

“Although the New World screwworm fly is not yet present in Texas or the U.S., its northward spread from Mexico toward the U.S. southern border poses a serious threat to Texas’ livestock industry and wildlife,” said Governor Abbott. “State law authorizes me to act to prevent a threat of infestation that could cause severe damage to Texas property, and I will not wait for such harm to reach our livestock and wildlife. With this statewide disaster declaration, the Texas NWS Response Team can fully utilize all state government prevention and response resources to prevent the re-emergence of this destructive parasite. Texas is prepared to fully eradicate this pest if need be.”

Sterile Flies are Key to Stopping NWS

Sterile insect technique, when paired with surveillance, movement restrictions and education and outreach, is an effective tool for controlling and eradicating NWS. Female NWS flies only mate once in their lives, so if they mate with a sterile male, they lay unfertilized eggs that don’t hatch.

Releasing sterile flies just outside of affected areas helps ensure flies traveling to new areas will only encounter sterile mates and will not be able to reproduce.

The updated strategy will include: “USDA will release sterile flies north of the current active NWS cases in Mexico in a proactive effort to create a sterile reproduction buffer zone if the fly moves north from Mexico.”

Because it is important to continue ongoing surveillance efforts while releasing sterile insects, it is possible that sterile NWS flies could be caught and/or reported within Texas. To ensure officials can tell the difference between sterile and wild NWS flies, USDA will dye the sterile pupae, and the dye will transfer to the sterile flies when they hatch. The fluorescent dye will glow under UV light and may also be visible to the naked eye. If a sterile fly is captured in a trap, this dye will allow animal health officials to quickly rule the fly out as a threat.

“USDA will continue to deploy its intensive NWS response efforts including implementing import protocols, ongoing surveillance and trapping efforts along the border, investing in NWS innovation, and supporting robust response activities in Mexico and Central America,” the release says.

Surveillance, Monitoring and Reporting Continues

USDA continues to lead intensive surveillance and monitoring systems along the U.S. border. Teams continue to check 121 NWS-specific traps across high-risk areas of border states and leverage thousands of fruit fly/insect traps aligned all along the Southern border. To date, more than 42,000 flies from traps in all locations have been submitted to APHIS NVSL for identification, with no NWS detections to date.

APHIS Wildlife Services is also leading a coordinated effort to inspect wildlife for signs of NWS infestation. To date, they’ve inspected more than 9,300 wild animals across 39 different species and 131 U.S. counties and found no signs of NWS infestations.

Texas Takes Preemptive Action

The Texas release says Governor Abbott actions against the threat posed by NWS include:

Directing the Texas Parks and Wildlife Department (TPWD) and the Texas Animal Health Commission (TAHC) to establish a joint Texas NWS Response Team.
Partnering with the U.S. Department of Agriculture and Secretary Brooke Rollins to create a new $750 million Domestic Sterile NWS Production Facility in Edinburg, Texas.

“I’m glad to see the urgency from the governor’s office matching the seriousness of this threat,” says Texas Ag Commissioner Sid Miller. “The Governor’s disaster declaration gives his task force greater authority, resources, and speed needed to confront the growing threat posed by the New World screwworm. This is a serious risk to our livestock industry and one that the Texas Department of Agriculture has been preparing for through our own heightened surveillance, coordination, and response planning.”

Miller adds, “This fight requires every available resource to be thrown at it without delay, and TDA will continue to work alongside our state and federal partners to protect our livestock, pets, wildlife, and Texas communities.”

For more information on NWS and USDA’s efforts, visit Screwworm.gov

USDA Announces New World Screwworm Grand Challenge

Wed, 21 Jan 2026 21:52:07 GMT

Today, U.S. Secretary of Agriculture Brooke L. Rollins announced the launch of the N ew World Screwworm (NWS) Grand Challenge. This funding opportunity marks a pivotal step in USDA’s comprehensive strategy to combat NWS and prevent its northward spread.

“This is a strategic investment in America’s farmers and ranchers and is an important action to ensure the safety and future success of our food supply, which is essential to our national security,” Rollins says. “These are the kinds of innovations that will help us stay ahead of this pest and protect our food supply and our economy, protecting the way of life of our ranchers and go towards rebuilding our cattle herd to lower consumer prices on grocery store shelves. We know we have tried-and-true tools and methods to defeat this pest, but we must constantly look for new and better methods and innovate our way to success. Together, through science, innovation, and collaboration, we can ensure we’re utilizing the latest tools and technology to combat NWS in Mexico and Central America and keep it out of the United States.”

As part of the Grand Challenge, USDA’s Animal and Plant Health Inspection Service (APHIS) will make up to $100 million available to support innovative projects that enhance sterile NWS fly production, strengthen preparedness and response strategies, and safeguard U.S. agriculture, animal health, and trade.

Priority Areas for Funding

APHIS invites proposals that support one or more of the following objectives:

Enhance sterile NWS fly production
Develop novel NWS traps and lures
Develop and increase understanding of NWS therapeutics/treatments (i.e., products that could treat, prevent, or control NWS) for animals
Develop other tools to bolster preparedness or response to NWS

The notice of funding opportunity, including application instructions, eligibility, and program requirements, is available on the NWS Grand Challenge webpage . Applicants can also find information on the ezFedGrants website  or  Grants.gov  by searching USDA-APHIS-10025-OA000000-26-0001.  

Eligible applicants are invited to submit proposals that align with and support these priorities by the deadline on February 23, 2026, at 11:59 p.m. ET.

Entities interested in submitting a proposal should ensure they are registered with the  U.S. Government System for Award Management (SAM) . Learn more about the basics of the funding process and  how to get ready to apply .  

Your Next Reads:
New World Screwworm Found in Newborn Calf 197 Miles from U.S.-Mexico Border
USDA Launches Screwworm.gov
The Smell You’ll Never Forget: A Calf Infested with New World Screwworm

As Screwworm Inches Closer, When Could the U.S. Reopen the Southern Border to Cattle Imports?

Tue, 06 Jan 2026 20:49:11 GMT

A newly confirmed case of New World screwworm (NWS) in northern Mexico is renewing concern among U.S. cattle producers and policymakers, as the parasitic fly continues to inch closer to the U.S.-Mexico border.

As reported by Drovers, on Dec. 27, Mexico’s National Service of Agro-Alimentary Health, Safety, and Quality (SENASICA) reported a case of NWS in a 6-day-old calf with an umbilical lesion in the municipality of Llera, located in the state of Tamaulipas. The location is approximately 197 miles south of the U.S.-Mexico border, and a reminder that NWS is still a high threat to the U.S.

Critical Timing with Calving Season Approaching

NWS, which was eradicated from the U.S. in the 1960s through an extensive sterile fly program, poses a serious threat to livestock. The larvae infest open wounds, feeding on living tissue and often leading to severe injury or death if untreated. Calving season is considered a particularly vulnerable period due to natural points of entry such as navels and birthing injuries.

Seth Meyer, director of the Food and Agricultural Policy Research Institute (FAPRI) and former chief economist for USDA, says the new case raises a tremendous amount of concern as USDA remains vigilant on keeping NWS out of the U.S. But Meyer says the growing proximity of NWS complicates already difficult decisions for cattle producers at calving season , which is a critical time of the year.

“There are concerns not just from a consumer standpoint, but also about whether southern producers are willing to retain heifers during calving season if there’s a risk of fly exposure,” he says. “Calving is a point of access for these animals, and that risk matters.”

Those decisions could have longer-term implications for herd expansion and cattle supplies, Meyer notes. If producers decide the risk is too great and opt against retaining replacement heifers, it could tighten supplies further down the road.

“That’s the last thing you want,” Meyer says. “You don’t want people giving up on retaining heifers and turning away from herd rebuilding.”

The Possibility of Reopening the Southern Border

The U.S. most recently closed its southern border to Mexican cattle imports in May of 2025 due to the rapid spread of NWS in Mexico. There were additional closures and reopenings in July 2025 as the situation evolved ultimately halting trade again to protect U.S. livestock.

Here’s a timeline so far:

November 2024: NWS was first detected in southern Mexico, leading to initial border closures and trade disruptions.
Feb. 1, 2025: A temporary ban was lifted after agreements for inspections.
May 11, 2025: U.S Secretary of Agriculture Brooke Rollins ordered an immediate suspension of imports due to NWS spreading closer to the border.
July 2025: A phased reopening began but was halted again after new NWS cases were found farther north, leading to another immediate closure of southern ports to protect American livestock.

Considering the cattle just south of the border are being vigilantly monitored and inspected, the bigger threat of NWS crossing the Southern border could be through wildlife . Still, as NWS gets closer, USDA is keeping the border closed and remaining cautious.

When could the U.S. reopen the border? That’s exactly what Farm Journal asked economists in the latest Ag Economists’ Monthly Monitor and the responses were extremely mixed. It’s important to note the survey was sent out prior to the most recent detection of NWS.

33% of economists say USDA could reopen the border in February 2026
25% say it could happen April through June
17% think the border could reopen July through September
And 17% were unsure.

For policymakers, the situation adds another layer of complexity as they balance animal health, trade and producer confidence. While officials stress that there is no immediate threat to the U.S. herd, the latest detection underscores the importance of surveillance, rapid response and continued cooperation between U.S. and Mexican animal health authorities.

As Meyer puts it: “There are a lot of balls in the air right now,” and preventing NWS from crossing the border remains a critical priority for the livestock industry on both sides.

Follow Farm Journal’s extensive coverage of the ongoing NWS situation.

Prepping Dairies for the Return of the New World Screwworm

Mon, 05 Jan 2026 22:00:59 GMT

As New World screwworm moves closer to the southern U.S., dairy farmers, veterinarians and industry leaders are paying closer attention. While it’s not time to panic yet, there is a shared focus on being prepared if the pest crosses the border.

Keith Poulsen, Ph.D., director of the Wisconsin Veterinary Diagnostic Laboratory at the University of Wisconsin, explained the urgency during a recent “Professional Dairy Producers” webinar.

“This is not just another fly,” Poulsen says. “The New World screwworm is the larval stage of a fly that actually burrows into live tissue. That’s what makes it unique and what makes it a genuine threat to cattle, other livestock and even people.”

The U.S. successfully eradicated the screwworm in 1960 using a method called the sterile insect technique. This approach involved breeding and releasing millions of sterile male flies into the wild. When these sterile males mated with wild females, no offspring were produced, slowly shrinking the screwworm population. Over time, this effort drove the pest out of the country.

“It took decades, but we pushed screwworm out of North America all the way into South America,” Poulsen explains.

Today, detections moving north through Mexico have veterinarians and animal health officials paying close attention. With confirmed cases now within roughly 70 miles of the Texas border, the concern is very real.

“We’ve seen this pest before,” Poulsen says. “The fact that it’s moving north again means we need to be ready.”

Why is This Fly Different?

Unlike flies that target manure or dead tissue, the New World screwworm lays eggs in living animals. When those eggs hatch, the larvae burrow into the tissue and feed, creating painful wounds that can rapidly worsen.

“They’re irritated because it’s painful,” Poulsen explains. “When those eggs hatch and the larvae start feeding, it creates abscesses. Abscesses are painful, and they can lead to sepsis or a generalized infection.”

Animal deaths aren’t usually common, but the damage does not need to be fatal to be costly. Livestock often lose condition, require treatment and can suffer carcass trimming or condemnation later.

“You might see it at slaughter when tissue has to be trimmed out or carcasses are condemned,” Poulsen says. “That’s where a lot of the economic impact shows up.”

What Should You Look For?

Poulsen stresses early detection depends less on new technology and more on careful observation. The good news is producers already do this every day.

“We call it active observational surveillance,” he says. “You already check your animals every day. Now you just add a heightened awareness for very specific signs.”

Producers should watch for changes in behavior, skin condition and overall comfort, including:

Unusual discomfort or behavior, such as head shaking, kicking at the body, tail swishing or animals isolating themselves from the group
Animals that just seem off, even if no obvious wound is visible at first
Open sores or abscesses, especially those that appear suddenly or worsen quickly
Foul smelling wounds, which can indicate infected or abscessed tissue
Clusters of lesions, rather than a single isolated wound. “You’ll often see chains of abscesses,” Poulsen explains. “They can range from blueberry sized to golf ball sized, and you’ll usually see more than one.”

Certain areas of the body deserve extra attention, particularly places animals struggle to brush flies away, including:

Udder cleft and teat base
Axilla or armpit area
Neck and dewlap
Along the topline or shoulders

In more advanced cases, larvae can be visible within the wound.

“If you see larvae or maggots coming out, that’s a real telltale sign,” Poulsen adds.

Identifying the Fly

Adult screwworm flies look different from common horn flies, but Poulsen cautions against relying on visual identification alone.

“They have a metallic green body, large heads and striping on the abdomen,” he says. “But it’s hard to tell for sure just by looking.”

(USDA Animal and Plant Health Inspection Service)

Instead, he encourages producers to involve their veterinarian and diagnostic labs early rather than trying to make the call themselves.

“If you think you see the flies, grab a couple, put them in a collection vial and give them to your veterinarian,” Poulsen says. “We’ll identify them for free. Our lab network is activated and trained to look for this.”

Is This Only a Southern Concern?

Texas and the broader Southwest face the highest risk because warm temperatures allow screwworm flies to survive year-round, giving the pest more opportunity to reproduce and spread. Still, Poulsen cautions that northern states should not assume they are completely safe.

“We move a lot of animals back and forth,” he says. “Wisconsin alone moves about 6,000 animals per month to and from Texas.”

Transporting calves south or bringing in animals from higher-risk areas can inadvertently introduce screwworm to northern herds. Even healthy-looking animals can carry early-stage larvae that are not yet visible.

“The risk up here isn’t zero, but it’s not as high as in the south,” Poulsen says. “The advice for those farms is simple. Look closely. If you see anything, say something.”

Cold weather slows screwworm activity, giving farms some seasonal relief. Still, producers need to stay alert as warmer weather returns.

“Now that we’re in the middle of winter, flies shouldn’t be an issue,” he says. “This season is more about keeping an eye out and staying ready for what spring might bring.”

What Happens if Screwworm Crosses the Border?

While no one can say exactly how regulatory responses would play out if screwworm returns, agencies are already preparing.

Federal and state animal health officials are increasing surveillance, testing and monitoring programs to catch the pest early. Rapid response plans are also being developed, including quarantine measures, movement restrictions and treatment strategies.

“We’re ramping up testing, education and surveillance,” Poulsen says. “It’s not just about detecting insect presence. It’s about rapid response, communication and ensuring we have animal movement protocols ready if needed.”

Public health is also involved.

“We had a human case in Maryland from someone who traveled to an endemic area,” he adds. “Public health found it, treated it and contained it. That tells me the system works, but we still don’t want it in our livestock.”

Making Biosecurity a Priority

Being proactive isn’t just about one pest. Recent research presented at the MILK Business Conference shows many U.S. dairy farms take a reactive approach to biosecurity, leaving operations vulnerable to evolving disease threats. About one-third of farms don’t regularly review their biosecurity plans, even as challenges like highly pathogenic avian influenza, bovine spongiform encephalopathy and New World screwworm continue to emerge.

The survey of more than 300 dairy producers found that while 68% of larger farms have a biosecurity plan, 34% do not review or update it regularly. The good news is that more than 70% of large dairies are working on improvements, showing parts of the industry are taking biosecurity seriously. Having these systems in place can make a real difference when it comes to spotting problems like screwworm early and responding quickly.

Awareness Over Alarm

Poulsen is quick to clarify that being prepared does not mean panicking. While screwworm has not been detected in U.S. livestock yet, thinking ahead can make all the difference.

“If animals are coming from a high-risk area, they may need to be treated before transport and monitored closely after arrival,” he says. On modern dairies, that is easier said than done because quarantine takes space and space costs money. That is why he encourages producers to start planning now.

“Talk to your veterinarian,” he says. “Ask what your biosecurity plan looks like if you have to bring animals in. Do you have a place to isolate them? How long would they stay there? What treatments would you use?”

He emphasizes that the goal is not fear but knowledge and readiness.

“This isn’t about fear. It’s about knowing what we’re up against and using every resource we have to protect our animals and our industry.”

While the threat of New World screwworm seems intimidating, Poulsen’s advice is simple. Keep up with the latest updates, pay close attention to your animals and reach out to your vet or state animal health officials sooner rather than later. Staying ahead now makes all the difference later.

“The consequence of missing it is very, very high,” Poulsen adds. “It is much easier to control it early than later.”

Looking ahead, he sees the current situation as the start of a longer process.

“We’re at the beginning of this, not the end,” Poulsen says. “That’s exactly why we’re having these conversations now.”

New World Screwworm Found in Newborn Calf 197 Miles from U.S.-Mexico Border

Wed, 31 Dec 2025 16:20:11 GMT

On Dec. 27, Mexico’s National Service of Agro-Alimentary Health, Safety, and Quality (SENASICA) reported a new case of New World screwworm (NWS) in a 6-day-old calf with an umbilical lesion in Llera, located in the state of Tamaulipas, approximately 197 miles from the U.S.-Mexico border.

According to the Texas Animal Health Commission, there have been no other detections in Tamaulipas or any evidence of established fly populations in the area.

To support a swift response if NWS reaches Texas, producers located on the southern border and travelers from NWS-affected areas should closely monitor animals for signs and promptly report suspected cases of NWS.

Read more about how to identify NWS:
The Smell You’ll Never Forget: A Calf Infested with New World Screwworm
Protect Your Livestock: Signs of New World Screwworm

A suspected NWS case requires immediate action, but it all starts with one thing: your call. If you suspect an infestation, report it right away.

The Texas Animal Health Commission recently posted this video explaining the process for producers to take if they suspect a NWS case:

What Are Some Key Concerns if NWS Crosses the Border?

Texas beef producer Donnell Brown says NWS poses a real threat to rural America.

“Fortunately, we made it to winter without a major screwworm infestation in the United States,” he says. However, as temperatures rise this spring and fly season begins again, I am deeply concerned that we could see an outbreak with devastating consequences for livestock and wildlife.”

Read more about NWS and winter:
Winter: The Secret to Slowing the Spread of Screwworm

Brown recalls the previous NWS outbreak in Texas.

“Compared to the last screwworm epidemic I experienced as a child, we now have far more effective parasiticides with extended protection for livestock,” he says. “Unfortunately, we still lack practical ways to treat or protect wildlife. After the screwworms were eradicated in the 1970s, it was 15 years before I remember seeing deer on our ranch. Today, deer are abundant and hunting has become a major economic driver for ranchers and rural communities.”

Read more about NWS treatment and prevention options:

FDA Approves Exzolt Cattle-CA1 for Prevention and Treatment of New World Screwworm
FDA Approves Dectomax-CA1 for Prevention and Treatment of New World Screwworm
New Technology to Combat New World Screwworm

Browns says if NWS cause significant wildlife losses, the ripple effects would be severe.

“Fewer hunters would travel from cities to rural areas, reducing spending on food, fuel, feed, lodging and other local necessities. This would harm rural economies already under pressure,” he explains. “The risk is especially high because fawns and many other wild mammals are born during fly season. Their wet navels become prime targets for screwworm infestation, making the potential impact on wildlife populations both immediate and profound.”

Read more about NWS and wildlife:
The Importance of Wildlife Monitoring for New World Screwworm

Sterile Flies Remain Key to Eradicating New World Screwworm

“The continued detections of New World screwworm near the Texas border are grim reminders of the serious threat this pest poses to our state,” says Texas Agriculture Commissioner Sid Miller. “Thanks to the efforts of USDA Secretary Brooke Rollins and APHIS working in coordination with Mexico, its northward spread has been halted, and this recent case promises to be a one-off, for now. But to fully eradicate this threat, the bottom line remains unchanged: we need sterile flies. I said as much a year ago when I criticized the Biden Administration’s failed efforts to corral this pest — dollars don’t kill screwworms, sterile flies do.”

Under President Trump’s leadership, Secretary Rollins and the USDA have now committed to a historic, targeted response that will deliver real results.

“Earlier this year, I was proud to stand alongside Secretary Rollins in Edinburg, Texas, as she unveiled her comprehensive five-point plan , and again at the Texas Capitol as that plan was expanded ,” Miller says. “I will continue to support and advocate for federal efforts to expand sterile insect fly production and infrastructure, because this proven strategy is key to the long-term eradication of New World screwworm.”

Current information related to NWS is available on the USDA-APHIS website , including a current situation map and table showing cases within 400 miles of the U.S.

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FDA Approves Exzolt Cattle-CA1 for Prevention and Treatment of New World Screwworm

Thu, 04 Dec 2025 18:42:23 GMT

On December 4, 2025, the U.S. Food and Drug Administration (FDA) granted conditional approval to Exzolt Cattle-CA1, a fluralaner topical solution from Merck Animal Health, for the use in beef cattle (≥ 2 months of age) and replacement dairy heifers (< 20 months of age). The approved uses include prevention and treatment of larval infestations by New World screwworm (NWS), and treatment and control of cattle fever tick.

“The FDA is leveraging every resource and authority at its disposal to ensure producers and veterinarians have the critical products they need to protect their livestock and safeguard our food supply against NWS and cattle fever tick,” said Timothy Schell, director of the FDA’s Center for Veterinary Medicine, in a press release . “We remain steadfast in our commitment to ensuring that animal drugs are safe and effective and that food from treated animals is safe to eat.”

While NWS has not yet been detected in the U.S., the threat persists just south of the border with a new case being reported yesterday. Cattle fever ticks, present along the U.S.-Mexico border in south Texas, are competent vectors of Babesia bovis and Babesia bigemina — agents of bovine babesiosis (Texas cattle fever).

“The threat of New World screwworm represents a growing concern to U.S. agriculture, potentially causing devastating economic losses for cattle producers that could reach hundreds of millions of dollars,” said Rick DeLuca, president of Merck Animal Health, in a news release . “We worked closely with the FDA to accelerate availability so that veterinarians and cattle producers will have access to a powerful new tool to protect cattle from these serious parasites, helping to safeguard the industry’s economic future and the nation’s beef supply.”

The conditional approval status reflects FDA’s determination that Exzolt Cattle-CA1 is safe for its labeled use and is reasonably expected to be effective, while requiring that its sponsor, Merck Animal Health, submit further data demonstrating its effectiveness over the next five years to support full approval.

Administration and Use Considerations

Exzolt Cattle-CA1 is a ready-to-use pour-on that delivers the active ingredient, fluralaner, to act systemically against infestations. Administration involves applying a narrow band of the solution from between the shoulder blades to the tailhead. It will be available in the first quarter of 2026 by prescription in 250 mL, 1 L or 5 L bottles.

After administration, there is a 98-day withdrawal period before slaughter to ensure meat from treated animals is free of drug residues. Use is prohibited in lactating dairy cattle, dairy calves, veal calves or bulls over one year of age that are intended for breeding.

This approval of Exzolt Cattle-CA1 complements that of Dectomax-CA1 , which was authorized in September 2025 for prevention and treatment of NWS infestations in cattle. Together, these two products give veterinarians and producers their first pharmacologic defenses against NWS.

Second Screwworm Detection 120 Miles from U.S. Border

Wed, 03 Dec 2025 20:54:05 GMT

There was a new detection of New World screwworm (NWS) in Montemorelos, Nuevo León, Mexico, approximately 120 miles south of the Texas border.

USDA’s Animal and Plant Health Inspection Service (APHIS) confirmed the case in a 22-month-old bovine transported from Veracruz to a feedlot in Nuevo León.

Texas Agriculture Commissioner Sid Miller in a press release emphasized that Texas remains free from detection, but that state officials and agriculture leaders cannot be complacent.

Texas Agriculture Commissioner Sid Miller today issued the following statement after being notified by the U.S. Department of Agriculture (USDA) of a new detection of the New World screwworm (NWS) in Montemorelos, Nuevo León, Mexico, approximately 120 miles south of the Texas… pic.twitter.com/Wb3uIwW3gf
— Texas Agriculture (@TexasDeptofAg) December 3, 2025

“We will keep working shoulder to shoulder with USDA, Mexican animal health authorities, and our own state agency partners to defend our border and Texans from this dangerous threat. We will protect our livestock, safeguard our economy, and do everything possible to keep the New World screwworm at bay,” Miller says.

He also encourages Texas producers to remain watchful for suspicious wounds, unhealed tissue, or maggot activity in livestock, wildlife, and pets, particularly in locations near the border.

Producers who suspect NWS should immediately contact their local veterinarian and state authorities. Early detection, strict livestock movement controls, screwworm fly suppression and rapid response are the best tools to combat this serious threat.

This detection marks the northernmost active case currently found in Mexico. It is also the second detection at the same Nuevo León feedlot since October. No additional cases were linked to the October detection, and both events appear tied to livestock movements from southern Mexico.

For more on NWS, including a current list of NWS detections within 400 miles of the U.S. visit Screwworm.gov .

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USDA Launches Screwworm.gov

Fri, 21 Nov 2025 20:52:12 GMT

Today, the U.S. Department of Agriculture (USDA) launched the new nnified New World screwworm (NWS) website, screwworm.gov . This dynamic new site centralizes NWS information available across the federal government and reflects our whole-of-government effort to fight this pest through implementation of Secretary Rollins’ comprehensive five-pronged plan .

“The Trump Administration is leading a whole of government effort to protect our nation’s cattle industry from the New World Screwworm. To ensure timely and effective communications, this new unified website will be a one stop shop for all screwworm related information and will help our stakeholders be better informed as new information comes available,” Rollins says in a news release . “We are grateful for the robust interagency collaboration, and we continue to work every day with our state and industry partners to implement our screwworm plan. This is a national security priority and it has the full attention of our team.”

Screwworm.gov has targeted resources for a wide range of stakeholders including livestock producers, veterinarians, animal health officials, wildlife professionals, healthcare providers, pet owners, researchers, drug manufacturers and the general public. It also has the latest USDA-verified information on cases and response activities in Mexico and U.S. preparedness efforts.

NWS Update

In a press release Friday, APHIS shared an update on the battle against NWS. According to the release, USADA in close collaboration with its interagency partners and Mexico’s El Servicio Nacional de Sanidad, Inocuidad y Calidad Agroalimentaria (SENASICA), has made considerable progress in reducing the overall threat of NWS to U.S. agriculture and mitigating northern movement of the fly within Mexico.

As of Nov. 21, NWS has not been detected in any animals or traps in the U.S., and the vast majority of cases within Mexico remain concentrated in southern parts of the country. The Trump Administration remains steadfast in its resolve to safeguard America’s rural economy, domestic food supply, and public health from this invasive pest.

“USDA is actively investing in physical infrastructure to expand our capacity for sterile fly production and dispersal, while APHIS’ technical experts continue their intensive work across multiple programs and disciplines to further strengthen our strategic planning and domestic preparedness,” the press release says.

Cross-Border Response and Collaboration

In October, USDA conducted its most recent audit of NWS response activities in Mexico. Evaluators documented great progress in management of NWS, with robust outreach and education, effective emergency response and treatment protocols, and expansion of the workforce and surveillance. While there is still work to be done, USDA and SENASICA are committed to continued collaboration to implement the joint NWS action plan.

“In the event of case detection in a new (previously NWS-“Free”) location within Mexico, USDA teams are on the ground working alongside SENASICA counterparts to ensure treatment of affected animals, epidemiological tracing, local surveillance, and timely dispersal of sterile flies,” the release explains.

The two isolated NWS cases in cattle in Nuevo León were categorized as “inactive” by SENASICA last month, after the animals received antiparasitic treatment and completed 21-day quarantines. No additional NWS cases or non-sterile flies have been identified through intensive surveillance and trapping in Nuevo León or any other border State.

As a precaution, APHIS will continue to direct the release of sterile flies across these northernmost detection areas until December. On Nov. 11, an NWS case was detected in Guerrero State (502 miles from the U.S. border). As with the Nuevo León cases, USDA had a sterile fly dispersal plan in place within 12 hours of notification. As of Nov. 21, the active case closest to the U.S. is in central Veracruz State, around 425 miles from the border.

In early November, President Claudia Sheinbaum welcomed Secretary Rollins and her team to the Presidential Palace to discuss continued collaboration on shared challenges including NWS, and the Secretary attended a separate meeting with SENASICA to review bilateral response activities. USDA Under Secretary for Marketing and Regulatory Programs Dudley Hoskins accompanied Rollins on the trip and visited the State of Chiapas to review NWS containment practices and enforcement.

Protecting the Border and Maximizing Our Readiness

USDA personnel at the southern border continue to strengthen monitoring systems for NWS. APHIS has equipped counties along the southern border in Texas, Arizona, New Mexico and California with approximately 120 monitored NWS-specific fly traps and more than 7,000 fruit fly “double duty” traps. To date, more than 30,000 U.S.-trapped flies have been submitted for NWS analysis; as of Nov. 21, all flies have been confirmed to be negative. Meanwhile, APHIS Wildlife Services teams have examined at least 6,642 wild animals across 28 species in 120 U.S. counties, finding all to be free of NWS infestation.

“Should this pest enter the United States in the future, we have the tools, resources, and response plans in place to rapidly contain and eradicate it,” the release stresses.

Following the Oct. 17 release of the draft NWS Response Playbook , APHIS Veterinary Services has been actively collecting stakeholder feedback to ensure the playbook’s operational useability and alignment with State and Federal response capabilities. The playbook and accompanying materials are living, dynamic documents that will continue to be refined in the coming months; comments and suggestions may be submitted to fad.prep.comments@usda.gov .

Taking the Fight to NWS

The release says COPEG’s sterile NWS production facility in Pacora, Panama, is operating at maximum production capacity (approximately 100 million flies per week). Aerial dispersal of sterile flies has continued uninterrupted in NWS-affected areas of southern Mexico, where joint response activities with SENASICA are largely focused.

On Nov. 13, APHIS announced the opening of a new sterile insect dispersal center in Tampico (Tamaulipas State), allowing for aerial dispersal over the detection sites in Nuevo León and replacing the use of ground release chambers in that location.

“This investment represents an important step forward in the NWS response as it creates greater flexibility and predictability in our deployment of sterile insects across northern Mexico and along the border, if necessary,” according to the release.

Construction is progressing on the sterile fly dispersal facility at Moore Air Base in McAllen, Texas, and it is on track to be operational in early 2026. USDA also continues to work closely with the U.S. Army Corps of Engineers (USACE) on planning for the domestic production facility for sterile flies.

In early November, COPEG hosted a team of technical experts from USACE, who were able to observe the production process firsthand and learn about facility requirements.

USDA is in the process of finalizing details for the NWS Grand Challenge — up to $100 million of new funding to combat the pest and prevent its spread northward. We’re calling on innovators, researchers, and industry leaders to help us enhance sterile NWS fly production and strengthen preparedness. Potential projects might include: enhancement of sterile NWS fly production; development of novel NWS traps and lures; increased understanding of NWS therapeutics/treatments in animals; or other tools to bolster U.S. preparedness or response to NWS. Monitor screwworm.gov and the APHIS stakeholder registry for updates on this opportunity.

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Next Step in the Screwworm Fight: USDA Announces Opening of Sterile Fly Dispersal Facility in Tampico, Mexico

Thu, 13 Nov 2025 18:38:40 GMT

USDA announced Thursday the opening of a sterile fly dispersal facility in Tampico, Mexico. The Tampico facility will allow USDA to disperse sterile flies aerially across northeastern Mexico, including in Nuevo Leon. This announcement is the next milestone in the fight against New World screwworm (NWS).

“The opening of the Tampico sterile fly dispersal facility is another incredibly important tool in our arsenal to stop the spread of screwworm. The facility will ensure flexibility and responsiveness in northern Mexico, giving us a greater ability to drop sterile flies and continue to push the pest south,” said U.S. Secretary of Agriculture Brooke Rollins in a press release . “Stopping the spread of screwworm is a top priority for the entire Trump administration.”

Last week Rollins met with Mexican President Claudia Sheinbaum and her counterpart Secretary Julio Berdegue on the joint response to NWS.

“We are boosting our efforts and completing a joint review of our screwworm operations in Mexico to ensure our protocols are being followed,” she says. “As we enter the winter months , we continue to prioritize the response in Mexico and the rest of our five-pronged plan to protect U.S. livestock and the livelihoods of American farmers and ranchers.”

A proven method for NWS eradication is releasing sterile male flies to mate with wild females collapsing the population over time. There are two methods of dispersing sterile insects – aerial dispersal and ground release chambers. Aerial operations are preferred because they allow for dispersal at a steady rate through a large area and also because sterile insects may be dispersed in areas that are unreachable from the ground. Ground release chambers are used when there’s a need to quickly deploy sterile insects outside of the dispersal facility range.

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According to the press release, USDA continues to disperse 100 million sterile flies per week in Mexico, but until now, aerial operations have been limited to southern Mexico, necessitating the use of ground release chambers in more northern areas of the country. Mass production and targeted dispersal of sterile flies remain critical components of our effective response.

Although Mexico continues to confirm new cases of NWS, the overwhelming majority of these remain in the far southern part of the country, with no significant northward expansion over the past several months. Should that change, the Tampico facility will allow USDA to immediately tackle any cases that occur elsewhere in Mexico.

The two northernmost detections (approximately 70 and 170 miles from the U.S. border, respectively) occurred in Nuevo León, on Sept. 20 and Oct. 5 , in young cattle transported from Chiapas, Mexico.

Neither case is still active and there have been no additional detections of NWS flies in traps or cases in animals in Nuevo Leon. USDA continues to disperse sterile insects in Nuevo Leon, and will now transition from ground release chambers to aerial dispersal in those areas.

USDA produces sterile flies for dispersal at the COPEG facility in Panama. USDA is also investing $21 million to support Mexico’s renovation of an existing fruit fly facility in Metapa — which will double NWS production capacity once complete. With ongoing support from APHIS technical experts, Mexico anticipates this sterile fly production to begin as soon as summer 2026.

To expand our domestic response capacity, USDA has also begun construction on a sterile fly dispersal facility at Moore Air Base in Edinburg, Texas, that is projected to begin operating in early 2026. APHIS is also expediting design and construction of a sterile fly production facility in southern Texas, with a targeted maximum capacity of 300 million sterile flies per week.

USDA continues to work with Mexico’s agriculture authority, SENASICA, to implement the collaborative NWS Action Plan and guide trapping, surveillance and movement protocols to help stop the northward spread of NWS.

Trade Mission While In Mexico

While Rollins was in Mexico last week, she also led the largest U.S. Department of Agriculture agribusiness trade mission in history. During the mission, 41 U.S. businesses, 33 cooperators and agriculture advocacy groups, six state departments of agriculture, and 150 participants conducted more than 500 business-to-business meetings during the three days.

According to a USDA press release , “This was a critical opportunity for American business to further trade ties and for USDA to continue its aggressive response to NWS in Mexico and continue to hold Mexico accountable for its commitments to the 1944 Water Treaty.”

Honored to lead the largest @USDA Agribusiness Trade Mission in US history to Mexico City!

Over three days, our delegation of 41 US businesses, 33 cooperators, 6 state departments of agriculture, and 150 participants held more than 500 business-to-business meetings - deepening a… pic.twitter.com/39rGi9Snhj
— Secretary Brooke Rollins (@SecRollins) November 13, 2025

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A Conversation With Ag Secretary Rollins on Labor, Disease and MAHA

Thu, 13 Nov 2025 13:33:15 GMT

U.S. Secretary of Agriculture Brooke Rollins stuck to streamlining the federal government labor rules to alleviate dairy’s worker crisis and said more aggressive measures are coming to prevent and contain disease, in an interview with Dairy Herd Management. Rollins this week was at the joint annual meeting hosted by National Milk Producers Federation, the United Dairy Board and the United Dairy Industry Association in Arlington, Texas.

While there, she said the H-2A visa program is particularly broken for dairy, which requires year-round support instead of seasonal workers. She also said measures, such as mandatory testing for lactating dairy cattle prior to interstate movement, are not aggressive enough to address modern biosecurity threats.

Below is a summary of Dairy Herd’s 20-minute conversation with Rollins, who discussed labor, disease prevention as well as her feelings on the “Make America Healthy Again” movement.

What Federal Efforts Are in the Works to Ensure Adequate Labor for U.S. Dairies?

One of the central concerns among dairy producers, and the entire industry, is comprehensive immigration reform. To put it in perspective, more than two-thirds of today’s 9.36 million dairy cows are milked by immigrant laborers in the U.S., according to the National Milk Producers Federation.

Currently, the H-2A visa applies strictly to seasonal or temporary labor. Dairy operations, however, require consistent, skilled workers every day of the year. Milking and caring for cows, managing processing facilities and ensuring food safety are daily tasks that don’t pause between seasons. This mismatch leaves dairy farmers and processors nationwide without a legal means to fulfill their guestworker needs.

In addition to the need for year-round help, Secretary Rollins notes farmers must interact with three different federal agencies to use the H-2A program. Moreover, the costs associated with securing labor have significantly increased, with reports from farmers in south Texas indicating average hourly costs, including transportation and housing, reaching $30 to $35 per hour. Comparatively, similar labor across the border is $2 per hour, Rollins says, illustrating a system that is both unsustainable and inherently unfair.

Ideally, any H-2A program changes will reduce costs and red tape, but comprehensive solutions ultimately require congressional action.

In addition to visa programs, Secretary Rollins says the current administration remains focused on sealing borders and mass deportations.

“Everyone understands the dynamics of an open border, and the millions and millions, we’re unable to count how many, that crossed during the last administration. The President’s No. 1 promise as a candidate in 2022 through 2024 was sealing the border and mass deportations,” she says. “Looking at this challenge through the lens of understanding labor is absolute when we can’t feed ourselves, combined with where we are in terms of immigration, those are the nuances.”

How is the Administration Addressing Threats to Animal Ag?
On day 1, after being sworn in as Secretary of Ag, Rollins was briefed on HPAI . She made it clear that while some measures, such as mandatory testing for lactating dairy cattle prior to interstate movement , had been enacted, a broader and more aggressive approach is necessary. Recognizing that maintaining the status quo was insufficient, a comprehensive strategy was essential — not just from USDA but across the entire federal government.

“I realize there are lots of opinions on my boss, President Trump, but I think the one thing that most people would agree on is that he leaves it all in the field. And, that we have to do everything we can for this moment that we were given to fix a very broken system, whatever that system may look like, in this case, which is animal disease,” Rollins says.

In February 2025, the Trump administration set forth a five-point plan to combat HPAI . Rollins notes the dairy sector, in particular, showcased remarkable adaptability to HPAI threats, demonstrating industry resilience and proactive measures.

Significant investments, such as a $100 million innovation grant , have been allocated to explore vaccines and therapeutic solutions. However, the complexities of viral mutations necessitate caution, especially regarding vaccination strategies, to prevent potentially more dangerous strains from emerging.

“I think we’re going to make more progress than perhaps has been made. Having said that, it’s a virus and the virus always wins,” she says, noting they are worried about New World screwworm and took aggressive actions to combat that by closing several ports.

“We’ve not imported new animals, which is one of the reasons beef prices are up, but we are looking now to figure out how to start reopening ports. I think we’ve gotten our arms around exactly what the problem is,” she says. “We’re building out new sterile fly facilities, which is the only way we eradicated it 30 to 40 years ago, but we have a really good system in place.”

Rollins shares collaborations with international counterparts are stronger, creating an unprecedented partnership with Mexican authorities to manage and preempt future animal agriculture outbreaks effectively. Enhanced border protocols, including disinfection and ivermectin treatments for imports, underscore a commitment to protecting livestock health.

“I feel confident that we are aggressively attacking all pieces of NWS,” she says.

What Does the MAHA Movement’s Mean for Dairy?
The “Make America Healthy Again” movement aims to revamp the nation’s food system, and Rollins offers reassurance dairy products at the forefront.

“Health care costs too much. We’re not getting the care we need, especially to vulnerable populations. How do we fix that?” she asks. “Over the last year, it is completely flipped to, what are Americans eating? What are we serving in our schools? What are we serving in our SNAP program, which 42 million Americans are on the food stamp program.”

While the current economic situation is troubling, Rollins is confident in the long-term potential for profitability and sustainability in the dairy industry.

“What milk, cheese and other dairy products mean as we completely and fundamentally shift our entire food system is our dairy industry is at the very front tip of the spear,” she says, noting the response markets are answering and the dairy industry, too, with the $11 billion in new processing plants, U.S. dairy is riding a wave of momentum that is fueled by consumer demand.

“In the long term, I’m not sure there is an agriculture industry that has more to gain and that will see more of a pivot toward real profitability and real sustainability than this [dairy] industry. I could not be more excited to help lead on that,” she says.

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Preparing for the Battle Continues: USDA Shares Screwworm Update and Releases NWS Playbook

Mon, 20 Oct 2025 17:14:21 GMT

U.S. Secretary of Agriculture Brooke Rollins shared a New World screwworm update on X Sunday night.

“First and most important — No new cases have been detected in the last seven days in Mexican states bordering the United States,” Rollins says. “USDA and our partners continue to lead an aggressive response to New World screwworm (NWS). This is a national security threat, and it has the full attention of the Trump administration.”

Updates Rollins shared included:

Dispersing 100 million sterile flies per week in Mexico produced at the COPEG facility with more than 40 dispersal flights throughout Southern Mexico per week.
“USDA closely monitors the locations of detections in Mexico and ensures shipments of sterile insects and release chambers are routed to the locations of the latest detections for dispersal,” she says.
Inspecting wild or feral animals for NWS infestation as part of wildlife management activities in Texas, with more than 1,670 animals inspected to date.
Working with Mexico on trapping and surveillance.
“USDA staff have confirmed 7,885 total confirmed NWS cases in southern Mexico, an increase of 838 cases since Oct. 2,” Rollins reports. “There have been zero detections in border states since Oct. 5.”
Construction update: The NWS Sterile Fly Dispersal Facility at Moore Air Base will open in early 2026. This facility will allow USDA to disperse 300 million sterile flies weekly at the border and in northern Mexico.

NWS Playbook Released

Rollins says on Friday USDA hosted a call with more than 200 state partners and stakeholders to release the new USDA NWS Response Playbook .

“This playbook reflects our current approach and response if we ever have a confirmed positive NWS in the USA,” Rollins explains. “We want our state and industry partners to continue to provide feedback on ways to make the playbook even stronger.”

Industry stakeholders can provide feedback and suggestions regarding the playbook to FAD.PReP.Comments@usda.gov.

🚨 𝐍𝐖𝐒 𝐔𝐏𝐃𝐀𝐓𝐄 🚨

FIRST and most important — No new cases have been detected in the last 7 days in Mexican states bordering the United States.@USDA and our partners continue to lead an aggressive response to New World Screwworm (NWS). This is a national security threat…
— Secretary Brooke Rollins (@SecRollins) October 20, 2025

Playbook Highlights

According the playbook, the phases of the response include:

Preparedness — planning, organizing, training, equipping, exercising, evaluating and taking corrective action to ensure effective coordination during an outbreak response.
Confirmation, or NWS establishment in the U.S. due to NWS myiasis in warm-blooded animals or detection of NWS fly.
Containment, or preventing the spread of NWS in early stages of infestation through measures such as early detection, quarantines and movement requirements, sterile insect technique (SIT) and surveillance to reduce spread in domestic animals and wildlife.
Mitigation, or minimizing the outbreak impact, by reducing the geographic extent of the affected area to reduce strain on resources, achieved largely through quarantines and movement requirements, SIT and surveillance, and constant evaluation of impacted areas.
Control, or demonstrating infestation is being mitigated based on epidemiology and surveillance.
Eradication, or demonstrating freedom from NWS in previously affected areas.

If NWS is found in the U.S., USDA APHIS Veterinary Services will provide guidance, support, resources and coordination during an outbreak. The approaches and tools included in the playbook reflect USDA APHIS guidance and aim to provide a practical framework to rapidly focus on priority activities. Tools and resources will be updated regularly as new guidance on NWS is released.

Managing an NWS Response: Key Activities

(USDA APHIS)

The playbook includes eight key response activities:

Effectively manage a coordinated response and communications with stakeholders and the public
Reduce spread to non-infested animals and prevent NWS from establishing in new areas
Manage NWS on infested premises
Implement NWS surveillance and management strategies in wildlife
Implement NWS fly surveillance and management strategies
Maintain continuity of business (COB)
Ensure information flow and management
Identify and maintain resource requirements

To learn more about the playbook, visit the New World Screwworm Emergency Response website.

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NWS Threat Update: New Case Detected 170 Miles From Border

Tue, 07 Oct 2025 12:40:35 GMT

U.S. Secretary of Agriculture Brooke L. Rollins shared on X that a new case of New World screwworm has been detected 170 miles from the U.S.-Mexico border.

“Today, I was alerted by the Mexican government that a new case of New World screwworm was detected in Mexico, 170 miles from our southern border,” she says. “At this time, we believe this to be an isolated incident and it is ~100 miles further south of the last detected case. We will have boots on the ground within hours to independently verify the situation.”

🚨 𝐍𝐖𝐒 𝐓𝐇𝐑𝐄𝐀𝐓 𝐔𝐏𝐃𝐀𝐓𝐄 🚨

Today, I was alerted by the Mexican government that a new case of New World Screwworm (NWS) was detected in Mexico, 170 miles from our southern border. At this time, we believe this to be an isolated incident and it is ~100 miles further…
— Secretary Brooke Rollins (@SecRollins) October 6, 2025

She reported USDA staff will begin trapping, surveilling and dropping sterile flies in this area in Mexico.

“Despite the Democrat Shutdown, the intrepid men and women at the USDA continue to work around the clock to protect our great nation. We will continue to update the public as the situation develop,” she says.

According to Reuters , the infested calf had originated from the south of Mexico and was intercepted in the town of Montemorelos, south of Monterrey. None of the other 84 animals in the same shipment were found to be infested, the ministry said in a statement.

Mexico’s National Service of Agro-Alimentary Health, Safety, and Quality (SENASICA) confirmed a case of NWS in Sabinas Hidalgo , located in the state of Nuevo León, less than 70 miles from the U.S.-Mexico border on Sept. 21. The new case according to SENASICA, is not related to the case that was detected in Sabinas Hidalgo.

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The Importance of Wildlife Monitoring for New World Screwworm

The Importance of Wildlife Monitoring for New World Screwworm

Mon, 06 Oct 2025 14:11:18 GMT

The New World screwworm (NWS) is a pest that no producer or veterinarian wants to see on a farm or ranch. However, with the recent active case identified just 70 miles south of the U.S.-Mexico border , it seems only a matter of time before this threat becomes reality.

While NWS is a threat to livestock operations, we must also consider the impact it could have on local wildlife. During the last outbreak of 2016-2017 in the Florida Keys, 136 wildlife cases were confirmed, and 15% of endangered Key Deer died. Along with concerns for wildlife health, wildlife monitoring has become an important tool for following the migration of these flies.

“Wildlife are a cherished natural resource and play vital roles in our ecosystem health,” says Dr. Marcus Blum, AgriLife Extension statewide specialist and assistant professor at Texas A&M. “Texas is home to more than 100 mammal species that are at risk if the fly re-establishes itself here.”

Screwworm Fly Migration

Most adult screwworm flies fly less than 10 miles searching for a host to lay their eggs in. While this natural migration is certainly affecting the spread of the pest, most of its travel is on infested animals.

“Most screwworm migration does not come from adult flies making heroic flights northward. Instead, it comes from the movement of infested animals — cattle, deer, wildlife — and yes, even in rare cases, people. Wherever the animal goes, the parasite goes with them,” said Dr. Christopher Lee on a recent episode of “Vet Watch”.

One of the biggest challenges with wildlife monitoring is that most free-ranging wildlife avoid human contact. Because of this, NWS infestations can go undetected — meaning large scale mortalities are possible.

Here are some things you can look for in wildlife you may observe:

Open sores and tissue damage on living wildlife. Maggots may be visible in wounds
Foul odor like rotting flesh
Strange behavior including head shaking, irritability, apparent discomfort, lethargy or isolation from other animals

Wildlife Affected by New World Screwworm

Chief among affected species are the more than 5 million white-tailed deer that call Texas home. White-tailed deer are highly susceptible and often show visible infestations in the head and neck areas. Since the last major NWS infestation in the 1960s, the Texas white-tailed deer population has grown from 500,000 to approximately 5.5 million in 2024. This increase in population also represents an increase in risk for NWS migration, as they are such good hosts for the pest.

Feral swine could also act as NWS carriers as their widespread presence and constant movement means they could spread infestations quickly. For cattle producers, this means that even if your herd is secure and well-maintained, an outbreak in nearby wildlife could easily spread onto your animals.

Wildlife susceptibility to NWS infestations varies by sex and season. This is due to seasonal behavior and environment changes.

How environmental temperatures impact fly activity and the alignment of this activity with season deer behaviors.

(Texas A&M Agrilife Extension)

NWS activity is at its highest in the summer when temperatures range from 70°F to 90°F. Unfortunately, this timing coincides with fawning season. Not only is the umbilical region of newborn animals highly susceptible to infestation, but NWS may also lay eggs on the mucous membrane of the genitalia.

In breeding season, male wildlife compete for mating dominance, often leading to wounds from fighting. These wound sites are the perfect place for NWS to lay their eggs.

Antler growth, antler shedding and velvet shedding also create opportunities for NWS infestation. For example, the Florida Keys outbreak occurred during rut season, and males had the highest mortality rates in Key deer.

How can you help monitor wildlfe?

Everyone who works the land or spends time outdoors can play a part in protecting against NWS. Ranchers, hunters and community members are often the first to spot unusual wounds on deer, feral hogs or other wildlife. If you’re using trail cameras, consider checking them regularly for any signs of wounded or abnormal appearing wildlife. A hunting stand can be a great vantage point for identifying infected animals. In more residential areas, security camera footage could be useful for monitoring wildlife. Also pay attention to scavengers. If you see vultures circling, investigate what is attracting them.

As always, do not attempt to approach live wildlife. Maintain a reasonable viewing distance for your own safety. If you suspect NWS in any wildlife you observe, including the observation of maggots, immediately report your sighting to your state animal health official and Animal and Plant Health Inspection Service (APHIS) office .

The battle against NWS isn’t just about livestock — it’s about the ecosystem around them. Wildlife can serve as both an early warning system and a pathway for infestations to spread. By recognizing the importance of wildlife monitoring, producers and veterinarians strengthen the shield that keeps herds and geographical regions safe from this destructive parasite.

Blum and colleagues have released a very informative fact sheet if you’re looking to learn more about wildlife monitoring and management for NWS.

Your Next Read: Winter: The Secret to Slowing the Spread of Screwworm

Winter: The Secret to Slowing the Spread of Screwworm

Thu, 02 Oct 2025 11:03:28 GMT

Winter or colder temperatures — it’s not something you typically hear livestock producers anticipating or praying for. But this year, as the threat of New World screwworm continues to inch closer to the U.S.-Mexico border, winter can’t come soon enough.

“Certainly, winter will be our friend,” says Chris Womack, a veterinarian and rancher from San Angelo, Texas. “Historically the flies were pushed south with frost.”

USDA Agricultural Research Service entomologist Kim Lohmeyer agrees we need winter to come fast. Lohmeyer serves as the laboratory director of the Knipling-Bushland U.S. Livestock Insects Research Laboratory in Kerrville, Texas, where she and her colleagues use modeling to know when and where NWS may show up in the U.S. They are partnering with Lee Cohnstaedt and his team at the National Bio and Agro-Defense Facility in Manhattan, Kan., to study the life stages of NWS and its susceptibility to temperature and weather.

“With the climate changes and weather patterns we have now, if this fly gets here, it can go a lot further north, a lot further east and a lot further west,” Lohmeyer says. “It’s something to keep an eye on.“

The Winter Win

So, what exactly does “winter” mean? Lohmeyer says NWS are fairly cold sensitive, so several days of sustained cold temperatures in around 30°F would be enough to suppress NWS.

The NWS’s ability to survive is restricted to locations where low temperatures are regularly above freezing. Ideal adult fly activity occurs at 77°F to 86°F and relative humidity of 30% to 70%.

“This fly really loves 81.5°F,” explains meteorologist Matt Makens. “The research shows that’s when they’re friskiest.”

Although the Sterile Insect Technique (SIT) remains a primary control mechanism, Makens says studies have made it clear that eradication success, outbreak intensity and re-emergence potential are closely tied to weather and climate.

“From seasonal wind patterns to monsoonal moisture, numerous environmental conditions shape the life cycle, spread and population dynamics of this parasite,” Makens explains. “Understanding these weather-related drivers is critical not only for control, but also in considering how long-term temperature trends have altered the geographic boundaries of screwworm viability since the major outbreaks of the 1950s and early 1960s.”

During a recent Cattlemen’s Call podcast Makens said weather is one of the main forces of spreading NWS.

“If we could control the weather, we could control the fly,” he stresses.

(Maps: Makens Weather)

Research indicates larval and pupal development cannot proceed below approximately 58°F and halts above 110°F. The optimal temperature for adult survival and reproduction lies around 81.5°F, a range common in tropical and subtropical climates like Mexico and Central America. NWS do not survive in regions with cold winters, though they may spread into these areas during the warmer months.

Impact of temperature on NWS:

Reduced activity: Adult screwworm fly activity is limited when temperatures are below 59°F.
Larval vulnerability: Pupae are vulnerable to soil temperatures below 46°F. Sustained maximums hotter than 95°F can also be limiting — extreme heat reduces adult fly activity and increases mortality in larvae exposed to hot surface soils.
Life cycle: While the entire life cycle can be completed in warm conditions, it takes longer in cooler, more temperate environments.

“One of the secrets to historically, the northern limit of screwworm, was basically a matter of how cold the winter got. That sort of limited how far it got,” says Derrell Peel, Oklahoma State University Extension livestock marketing specialist. “In years when it was warmer, it would go farther. It would overwinter farther north, but in general, that’s going to set the upper limit, or at least it does if it’s not under control in any other way. That will limit its northward, northern movement, for sure.”

1972 NWS data (A) Monthly maps of observed cases of myiasis in Texas during the 1972 outbreak. Highest abundance occurred in August, and the length of all other density colour bars were scaled to it (bars in right hand margin of each map). The maximum density is at the top of each colour bar with the highest midseason incidence occurring in south central Texas. (B) Histogram summarizing the monthly total statewide data. (C) Map of total cases of myiasis during 1972.

(Medical and Veterinary Entomology)

Fly Season

David Anderson, Texas A&M professor and Extension specialist, says, historically, the fly season is April to October.

“If we get a really cold winter, that helps us,” Anderson adds. “It buys us some more time. But things are warmer now than it used to be. Fly season may not be that April to October anymore.”

NWS’s typical life cycle lasts about 21 days in warm weather and slightly longer in cooler climates. According to Texas A&M AgriLife Extension Service, NWS fly life cycle is highly sensitive to temperature:

In warm (more than 80ᴼF daytime highs) and tropical conditions, the full life cycle may be complete in two to three weeks.
In more temperate conditions, the life cycle may take three to four weeks.
In cooler conditions, the life cycle may take up to two to three months.

It is important to understand that the flies do not die at these lower activity temperatures, but prolonged exposure to these temperatures can reduce populations or active infestations.

Texas rancher Wayne Cockrell says NWS’s entry into the U.S. is inevitable but suggests winter and colder weather might temporarily delay the spread until next April or May. Cockrell serves as the Southwestern Cattle Raisers Association director and chair of the cattle health and well-being policy committee.

“We should be within 60 days hopefully when cold weather helps in two-thirds of the state,” Cockrell explains.

Rainfall and Monsoon Factors

Makens says while temperature defines where screwworms can survive, rainfall and moisture influence when and how intensely they can thrive. Outbreaks often follow moderate to heavy rainfall by improving conditions for larval survival.

He explains tools like the Palmer Crop Moisture Index (CMI) have shown promise in predicting screwworm risk, with higher-than-normal CMI values sometimes preceding population spikes.

When rainfall coincides with favorable temperatures, screwworm activity tends to increase. In contrast, hot and dry conditions tend to suppress survival and reproduction.

“One of the most striking climate connections is the role of seasonal monsoon winds in transporting screwworms over long distances,” Makens explains. “In multiple outbreak years, adult flies were documented migrating northward into Texas and the desert Southwest via the North American Monsoon (NAM) — a seasonal pattern that delivers moisture to northwestern Mexico and the U.S. Southwest from June through September. During the summer, prevailing winds shift from west to a more humid, southerly flow, creating favorable conditions for fly migration from central and southern Mexico into their northern states and, at times, into the southern U.S. The NAM this year had an early start and gave significant rainfall to parts of Arizona and New Mexico. The NAM typically calms by early fall.”

In the 1960s, these wind-assisted movements allowed the temporary re-establishment of breeding populations even after local eradication. In some years, migration spanned hundreds of miles, connecting source populations in northern Mexico to re-infestations in Arizona and New Mexico.

“This atmospheric ‘conveyor belt’ remains a critical concern in surveillance strategies for livestock-producing regions of the Southwest,” Makens says. “The 2025 monsoon was undoubtedly a factor in the most recent northward migration of NWS.”

If NWS should cross the border, it will be key for producers to coordinate management practices with weather patterns expected for their region.

“Ultimately, weather patterns act as both a barrier and bridge for screwworm activity,” Makens summarizes. “Knowing how and when the balance tips is essential to preventing the return of one of the industry’s most damaging parasites.”

Here’s to hoping Old Man Winter decides to arrive quickly and help buy livestock producers and government leaders more time to prepare to battle NWS.

Your Next Read: The Battle at the Border

FDA Approves Dectomax-CA1 for Prevention and Treatment of New World Screwworm

Tue, 30 Sep 2025 19:04:12 GMT

Today, the U.S. Food and Drug Administration conditionally approved Dectomax-CA1 (doramectin injection) injectable solution for the prevention and treatment of New World screwworm larval infestations, and prevention of NWS reinfestation for 21 days.

According to Zoetis, this conditional approval applies to beef cattle, female dairy cattle less than 20 months of age, pregnant beef cows, newborn calves and bulls.

“We understand the urgency with which America’s farmers and ranchers are asking for tools to fight New World screwworm,” says FDA Commissioner Marty Makary, M.D., M.P.H. in a press release . “Today’s conditional approval – the first in the U.S. for NWS – shows our dedication to rapidly advancing important animal medicines when they are needed most. We continue to work tirelessly to complete review of other NWS products to protect multiple animal species in the U.S.”

Dectomax-CA1 is eligible for conditional approval because it is intended to prevent and treat a serious or life-threatening disease in cattle, it addresses an unmet animal health need, and demonstrating effectiveness of the drug would require complex or particularly difficult studies.

“Under this conditional approval, the FDA has determined the drug is safe and has a reasonable expectation of effectiveness. We are making this treatment available to cattle producers immediately while the sponsor collects the data needed for a full approval,” says Timothy Schell, Ph.D., acting director of the FDA’s Center for Veterinary Medicine. “The FDA will continue to expedite review of animal drugs to help the U.S. fight this devastating threat to our nation’s livestock and the livelihoods of the farmers and ranchers who care for them.”

Dectomax is already fully approved under a New Animal Drug Application for treatment and control of certain nematode and arthropod parasites in cattle and swine. Dectomax and Dectomax-CA1 contain the same active ingredient (doramectin injection) at the same dose. Because the original approval of Dectomax included adequate target animal safety studies, manufacturing information, and human food safety information, the FDA did not require new information to support those aspects for the conditional approval of Dectomax-CA1.

“New World screwworm has the potential to bring unprecedented economic and animal health harm to livestock producers,” says Mike Lormore, DVM, MS, MBA, director of cattle and pork technical services at Zoetis. “Our top priority is to support keeping animals healthy and provide timely, efficacious solutions to our customers and partners. With this conditional approval, Dectomax-CA1 Injectable can now be used as part of safe, effective control measures against New World screwworm.”

The withdrawal period for cattle is 35 days for Dectomax-CA1, as it is for Dectomax. Warnings to prevent drug residues in meat from treated cattle are the same for Dectomax-CA1 as for Dectomax: Not for use in female dairy cattle 20 months of age or older. A withdrawal period has not been established for this product in preruminating calves. Do not use in calves to be processed for veal.

In the first half of 2026, producers and veterinarians will begin to see the 250-milliliter and 500-milliliter bottles of Dectomax Injectable with a new label for Dectomax-CA1 (doramectin injection). Dectomax-CA1 is the same effective doramectin formulation as Dectomax Injectable. Dectomax-CA1 label will contain both Dectomax and Dectomax-CA1 indications while each drug has a unique application number.

To reduce the risk of antiparasitic resistance and preserve drug effectiveness against other parasites, producers and veterinarians are encouraged to use antiparasitic drugs like Dectomax-CA1 only when medically necessary, in accordance with the product labeling, and as part of a comprehensive parasite management strategy.

Livestock producers are encouraged to work closely with their herd veterinarian to implement strategic prevention and control measures. Visit Zoetis’ website for more information about Dectomax-CA1.

New Technology to Combat New World Screwworm

Tue, 30 Sep 2025 15:41:26 GMT

The U.S. Department of Energy’s National Nuclear Security Administration’s (NNSA) Office of Radiological Security (ORS) is partnering with Texas A&M University to combat New World screwworm (NWS) .

On Sept. 21, USDA announced NWS had been found less than 70 miles from the U.S. border near one of the most heavily trafficked commercial thoroughfares in the world.

Working with Texas A&M’s National Center for Electron Beam Research (NCEBR), NNSA is advancing the Sterile Insect Technique (SIT) using electron beam (eBeam) technology in place of radioactive cobalt. SIT effectively prevents the spread of NWS by releasing sterilized male screwworms to halt reproduction and reduce their population.

According to the release, ORS’s mission includes preventing the misuse of highly radioactive materials and promoting innovative alternatives like eBeam devices. The eBeam technology eliminates the need for radioactive sources, which could be used for nefarious purposes if they fell into the wrong hands.

This collaboration enhances radiological security best practices nationwide, thus strengthening national security.

“Our mission-driven partnership with Texas A&M is essential to advancing American innovation in eBeam applications and enhancing our national security,” says Kristin Hirsch, Director of ORS. “With the support of Texas A&M AgriLife experts, NNSA is able to help combat the spread of the NWS, building stronger food systems and safer communities across the country.”

U.S. Secretary of Agriculture Brooke Rollins recently announced a new NWS fly dispersal facility in Texas and a five-pronged plan for eradicating the pest. The plan includes the USDA pursuing innovative research, such as eBeam and other technologies.

Currently, SIT relies on cobalt-60 gamma sterilization. But cobalt-60 carries significant radiological security risks, so NNSA, NCEBR and Texas A&M’s Department of Entomology have worked to find replacement methods. Through modeling studies sponsored by NNSA and conducted by Texas A&M since 2023, researchers identified eBeam technology as a viable alternative and are working to make it available to USDA to combat NWS.

The eBeam system at work, sterilizing screwworm pupae. This technology is vital for protecting U.S. agriculture and radiological security.

(U.S. Department of Energy NNSA)

NNSA has been collaborating on the development of an eBeam system to be used for chemical remediation, another critical area where cobalt-60 use could become a risk. NNSA is repurposing this technology toward NWS response and accelerating development to make eBeam available to USDA by early 2026.

Once integrated into a rearing facility, it could create more than 100 million sterile flies in 24 hours. That’s a vast improvement compared to cobalt-60, which can take a week to do the same amount. This efficiency would be a game-changer in NWS response.

Your Next Read: The Battle at the Border

U.S.-Mexico Border Battle Continues As the Threat of New World Screwworm Intensifies

Wed, 24 Sep 2025 20:04:06 GMT

With New World screwworm (NWS) confirmed just 70 miles from the U.S. border , producers, government officials and industry leaders are taking action. Finding NWS along one of the most heavily trafficked commercial thoroughfares in the world from Monterrey, Nuevo Leon, to Laredo, Texas, is a red flag for the industry. Emphasizing the importance of maintaining strong safeguards, it’s time to plan for not “if but when” NWS crosses the border.

On Monday, Secretary of Agriculture Brooke Rollins confirmed protecting the U.S. from NWS is non-negotiable and a top priority for President Trump.

UPDATE ON SCREWWORM THREAT:

Protecting the United States from New World Screwworm is non-negotiable and a top priority for @POTUS.@USDA landed boots on the ground this morning in Nuevo Leon, physically inspecting traps and dispersing sterile flies after the detection of the…
— Secretary Brooke Rollins (@SecRollins) September 23, 2025

“The southern border remains closed to livestock trade, and we are aggressively expanding trapping and surveillance,” she wrote. “At the same time, we’re expediting operations at our sterile fly dispersal facility at Moore Air Base in Texas .”

On Tuesday, Secretary of Agriculture Brooke Rollins reported 80,000 sterile flies were released on “spot” and nearly 200 surge staff had been deployed to Mexico.

Thank you, @IngrahamAngle, for paying attention to this important issue. Due to multiple failures from our southern neighbors and failure to act in the last Admin, the devastating parasite New World Screwworm is knocking on our southern borders door. We’re not waiting, we’re… pic.twitter.com/ZO5Vx5oes8
— Secretary Brooke Rollins (@SecRollins) September 24, 2025

Mexico’s Response To New World Screwworm

According to Reuters, Mexican’s agriculture ministry said there is no risk of adult screwworm fly emergence due to the early detection of the infected bovine, which was confirmed on Sept. 21. The infected animal was in a shipment of 100 animals originating from the Gulf Coast state of Veracruz, according to the statement.

Fly traps in northern Mexico have not detected a single screwworm fly.

U.S.-Mexico Border Remains Closed to Cattle Trade

The Mexican border closure remains a topic of debate. The September Ag Economists’ Monthly Monitor found 80% of ag economists surveyed oppose reopening the border to Mexican cattle due to screwworm risks.

(Farm Journal)

The border closure has created significant division within the cattle industry with producers, feeders and industry leaders on both sides of the fence.

“We have some cattle people that are glad it’s closed. We’ve got others who are hit pretty hard and are not happy about it,” explains David Anderson, Texas A&M professor and extension specialist — livestock and food product marketing.

NWS is a threat the industry can not ignore, says the ag economist with more than 30 years under his belt.

“I think this is the most serious problem the industry has faced since I’ve been a livestock economist,” he stresses.

From his perspective, keeping the border open with heightened monitoring and surveillance could have potentially been more effective than implementing a total closure.

“If we go back and look at data from the early ‘70s, when we had a big screwworm outbreak in the U.S. and Mexico, the border was open,” he says. “I probably would have leaned to not closing the border to begin with. I understand why you would want to do that, but I don’t know that it’s ended up reducing the likelihood that we’re going to get screwworms, and yet we’re paying a price for that.”

According to Anderson the economic consequences to the border being closed are:

Significant loss of approximately 26,000 imported cattle weekly
Estimated 18% reduction in cattle placements in Southern plains
Contributed to tighter beef supplies and higher consumer prices
Substantial economic hit to cattle feeders and ranchers

At this point, he’s quick to admit keeping the border closed is the best option.

When it comes to reopening the border, Derrell Peel, Extension livestock marketing specialist with Oklahoma State University, suggests the decision is not straightforward.

“Given everything I’ve experienced, it’s probably prudent to leave the border closed,” he says.

He adds any reopening should be “under very, very controlled, limited circumstances.”

Peel emphasizes the need for a collaborative approach with Mexico.

“We’re kind of in it together, and so whether it’s here or there, we’ve got to work together,” he summarizes. “We’re going to need to control it in both places. Otherwise, it’s not going to benefit either one of us.”

He also points out not everybody in Mexico is sorry the border is closed. For example, cattle buyers in Mexico can source cattle cheaper because the border is closed.

“Keeping the border closed does affect the movement of cattle south of the border ... it builds a backstop for cattle movement north,” he adds.

Peel notes cattle from Central America to Panama have increasingly made their way to the Mexican market, which validates NWS movement in Mexico and why recent confirmation has occurred.

“The longer this goes on, the more the Mexican industry will adjust,” he says. “It might permanently change the way the [U.S. and Mexico] work together.”

Texas Rancher Weighs In On Impact of New World Screwworm

Texas rancher Wayne Cockrell says the parasite’s entry into the U.S. is inevitable, suggesting that winter and colder weather might temporarily delay the spread until next April or May. Cockrell, who serves as the Southwestern Cattle Raisers Association director and chair of the cattle health and well-being policy committee, recently joined AgriTalk to talk about NWS.

“We would much rather stop this on Mexico’s southern border than our Southern border,” Cockrell says.

Mexican feeder cattle traditionally represented 30% of Texas feedyard inventory, he adds, but with current restrictions, feedlots are adapting.

“I think a lot of those feedyards have moved to the dairy-cross side,” he adds. “They have had to change the way they do business.”

Noting the broader economic implications of the border closure, 1.2 million fewer cattle for Texas represents “about two weeks” of impact nationwide, according to Cockrell.

“Winter and sterile flies is what we need now,” Cockrell summarizes.

Your Next Read: The Smell You’ll Never Forget: A Calf Infested with New World Screwworm

Mexico Confirms Case of New World Screwworm 70 Miles from U.S. Border

Mon, 22 Sep 2025 11:51:42 GMT

Mexico’s National Service of Agro-Alimentary Health, Safety, and Quality (SENASICA) confirmed a new case of New World screwworm (NWS) in Sabinas Hidalgo, located in the state of Nuevo León, less than 70 miles from the U.S.-Mexico border on Sept. 21.

USDA reports this is now the northernmost detection of NWS during this outbreak, and the one most threatening to the American cattle and livestock industry. Sabinas Hidalgo is located near one of the most heavily trafficked commercial thoroughfares in the world, the major highway from Monterrey, Nuevo Leon, to Laredo, Texas.

“Protecting the United States from NWS is non-negotiable and a top priority of the Trump Administration,” U.S. Secretary of Agriculture Brooke L. Rollins said in a release . “This is a national security priority. We have given Mexico every opportunity and every resource necessary to counter NWS since announcing the NWS Bold Plan in June 2025.”

Rollins says the U.S. will not rely on Mexico to defend U.S. agriculture.

“We are firmly executing our five-pronged plan and will take decisive action to protect our borders, even in the absence of cooperation,” Rollins said. “Furthermore, we will pursue aggressive measures against anyone who harms American livestock.”

The previous northernmost detection was reported approximately 370 miles farther south on July 9 in Veracruz, USDA reports.

SENASICA preliminary reports indicate the affected animal — an 8-month-old cow — had recently been moved to a certified feedlot in Nuevo León from a region in southern Mexico with known active NWS cases. USDA says this potential link to animal movement underscores the “non-negotiable need for Mexico to fully implement and comply with the U.S.–Mexico Joint Action Plan for NWS in Mexico.” U.S. ports remain closed currently to imports of cattle, bison, and horses from Mexico.

USDA has been actively monitoring nearly 8,000 traps across Texas, Arizona and New Mexico. More than 13,000 screening samples have been submitted to date, with no NWS flies detected. USDA said it will continue to analyze all new information related to the recent case in Nuevo León and will pursue all options to release sterile flies in this region as necessary.

As well, USDA will release a significant plan soon to help rebuild the American cattle supply, incentivizing ranchers and driving a full-scale revitalization of the American beef industry, the release said.

USDA Leads An Aggressive National Response
USDA reports it’s comprehensive strategy includes the following immediate actions:

Innovating Our Way to Eradication
USDA is investing $100 million in breakthrough technologies through the NWS Grand Challenge. This program will solicit ideas to enhance sterile fly production and develop new tools such as advanced traps, lures and therapeutics. USDA says it’s also exploring and validating technologies like e-beam and x-ray sterilization, genetically engineered flies, and modular sterilization facilities through public listening sessions and ongoing evaluations.
Protecting the U.S. Border
USDA has begun construction on a domestic sterile fly dispersal facility at Moore Air Force Base in Edinburg, Texas. This $8.5 million facility, expected to be mostly complete by the end of 2025, will be capable of dispersing up to 100 million sterile flies per week, USDA says. The U.S. Army Corps of Engineers is working with USDA on plans for for construction of a domestic sterile fly production facility in Southern Texas, with a projected capacity of 300 million sterile flies per week.
Strengthening Surveillance and Detection
USDA has been actively monitoring nearly 8,000 traps across Texas, Arizona and New Mexico since July. To date, more than 13,000 screening samples have been submitted, with no NWS flies detected. USDA continues to disperse 100 million sterile flies per week in Mexico, sourced from the COPEG facility in Panama. In addition, USDA is providing support to Mexico to renovate a production facility in Metapa, which is expected to produce an additional 60–100 million sterile flies.
Enhancing Public Awareness and Education
APHIS has published an updated national disease response strategy and is providing training and webinars for federal, state, Tribal and veterinary partners. Outreach materials, including pest ID cards and alerts, are being distributed along the U.S.–Mexico border. APHIS has held over 50 stakeholder meetings and continues to expand outreach efforts.
Coordinating with Mexico and International Partners
Following detections in Oaxaca and Veracruz, USDA closed southern ports of entry to livestock trade after a case was reported 370 miles from the U.S. border. USDA is conducting monthly audits of Mexico’s NWS response and is helping the country develop a more risk-based trapping plan, especially in Veracruz and along the border. Mexico currently deploys traps in high-risk areas, with USDA support.

USDA is supporting hiring of over 200 surge staff for trapping and animal movement control in Mexico. As well, SENASICA has launched a dashboard that tracks NWS cases across Mexico. This enhances USDA’s ability to monitor the situation south of the border, better assess risk, and deliver more effective operational responses in coordination with Mexican authorities.
Unprecedented Interagency Collaboration
Collaborating agencies include: Centers for Disease Control and Prevention, Food and Drug Administration, Department of the Interior, Department of Energy, Department of Homeland Security, Environmental Protection Agency, and the Department of State. This collaboration is guided by the U.S. One Health Coordination Unit for NWS (U.S. OHCU–NWS), co-led by USDA, CDC, and DOI, the release said.

Watch Out for Signs of NWS
NWS maggots most often enter an animal through an open wound and feed on the animal’s living flesh. They can infest livestock and other warm-blooded animals, including people.

USDA urges residents on the southern border to check their pets and livestock for signs of NWS .

“Look for draining or enlarging wounds and signs of discomfort,” USDA said. “Also look for screwworm larvae (maggots) and eggs in or around body openings, such as the nose, ears, and genitalia or the navel of newborn animals. If you suspect your animal is infected with screwworm, contact your state animal health official or USDA area veterinarian immediately.”

Although not common in people, if you notice a suspicious lesion on your body or suspect you may have contracted screwworm, seek immediate medical attention.

New World Screwworms Could Prey on Calves and Other Species

Tue, 02 Sep 2025 20:48:46 GMT

There was a time in the not-so-distant past when some Texas cattle hands riding the range had just one job: detecting and treating “wormies.”

The wormies were calves infected with New World screwworm (NWS) , according to San Angelo, Texas, veterinarian and rancher Dr. Chris Womack. He said calves are the perfect prey for NWS, because, unlike most other myiasis parasites that feed on dead and necrotic tissue, NWS feed on living tissue.

On a recent episode of the Have You Herd? podcast from the American Association of Bovine Practitioners, Womack noted one of the ideal feeding sites for the burrowing NWS myiasis (maggots): the fresh navel of a newborn calf, along with any other open wounds like disbudding sites. But cattle and calves certainly are not the only hosts of NWS. Infestations can occur in all mammals, including humans.

That fact leaves Womack concerned about the possible spread of the pest. If it does cross the U.S. border, he believes the “sentinel animal” in which it is first detected will be either a companion animal or a wildlife species.

The current rate of spread also alarms him. NWS was basically eradicated from the U.S. in 1966, thanks to collaborative biological efforts that resulted from public-private partnerships between donors and the U.S. and Mexican governments. “At the time more than $2 million in private funds were raised,” he Womack shared. “It was that big of deal to producers that they were willing to put their own dollars up to fight it.”

As an example, the state of Texas lost an estimated 180,000 head of cattle to NWS in 1935 alone, according to T.R. Lansford III, DVM, deputy executive director and assistant state veterinarian with the Texas Animal Health Commission.

“Through medicine or miracle, they figured out they could irradiate the male fly and make him sterile,” Womack recalled. Because NWS females mate only once in their lifetimes, mating with a sterile male results in sterile larvae, breaking the fly’s production cycle.

“They bred and raised hundreds of millions of sterile male screwworm flies and blanketed the southern U.S. border with them,” said Womack. After they had pushed them out of the United States, those same efforts continued in Mexico for 25-30 years, until the parasite had been driven all the way across the Panama Canal and south of the Darien Gap.

But that progress shifted in the second half of 2024. Womack said a rancher in Panama told him NWS had been detected in Panama in early August 2024. “From that time until Thanksgiving, it migrated clear across Central America and into Chiapas, Mexico,” noted Womack. “That’s really terrifying.”

In addition to closing – then re-opening and closing again – the U.S./Mexican border to imports of cattle, bison, and horses, USDA also is ramping up eradication efforts in Mexico and Central America. State departments of agriculture in the border states of New Mexico, Texas, and Arizona also are involved. But in the meantime, the deadly parasite has continued its march north through Mexico, and has been detected within 370 miles of the U.S./Mexico border.

Womack also is concerned that range cattle and wildlife are not as closely observed as they used to be. And while there may be fewer cattle on open pastures in Texas compared to 60 years ago, Texas is now home to tens of thousands of dairy calves at calf ranches, many of whom travel to various outposts around the country as they mature.

USDA resources indicate that NWS flies are slightly larger than the common housefly. They have orange eyes, a metallic blue or green body, and three dark stripes along their backs. Symptoms of effected animals include irritated behavior, head shaking, the smell of decay, and the presence of maggots in open wounds.
Producers who suspect their animals may be infected with NWS should contact their veterinarians and are encouraged to submit maggot samples to a diagnostic lab.

Womack lamented that because the problem was so well-controlled for so long, there is a generational gap in knowledge about NWS. “Because it was so fantastically eradicated, it was a non-issue for decades. But now it’s an issue again. We need to be aware of and vigilant about this problem,” he stated.

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