New World Screwworm
While USDA eradicated New World screwworm from the U.S. in 1966, there’s a constant risk of re-introduction. The parasitic fly larvae eat the living tissue of warm-blooded animals, such as cattle, causing serious, often deadly damage. The National Cattlemen’s Beef Association has warned it’s not a matter of if — but when — the pest makes its way back into the U.S.
Surveillance, reporting and veterinary partnerships are framed as critical ways to prevent a single case from becoming a national crisis.
From the evolving H5N1 virus to the looming screwworm threat, discover why a line of separation is the new strategic foundation for safeguarding the U.S. milk supply in 2026.
A new genetic innovation from the Agricultural Research Service aims to produce 100% sterile male flies, maximizing facility efficiency and safeguarding the U.S. livestock industry from NWS.
Following extensive industry feedback, the updated guide provides a science-based roadmap for states, ranchers and veterinarians to combat potential NWS outbreaks.
Kansas State Veterinarian Dr. Justin Smith outlines a coordinated plan built on surveillance, targeted treatment and movement controls to protect cattle operations while preserving business stability.
FDA issues emergency use authorization for topical spray to prevent and treat New World screwworm in multiple species.
FDA grants first emergency use authorization for an over-the-counter product for the prevention of NWS infestations in cattle.
If NWS does cross the border, quarantine and movement controls will be designed to inspect and treat affected animals. Adis Dijab, a veterinarian with APHIS, says this means producers can clear the rest of the herd and continue business.
Texas issues a statewide disaster declaration and USDA makes strategic reallocation of sterile flies to safeguard the U.S. livestock industry and public health.
Driving innovation to combat NWS and prevent its northward spread.
With a New World screwworm case now less than 200 miles from the U.S. border, Seth Meyer says the growing threat adds risk and uncertainty for cattle producers making critical calving-season decisions.
It’s time to start thinking about how to protect herds from New World screwworm before it reaches the U.S.
Texas producers need to remain on alert as NWS continues to move north. The newest detection is in the state of Tamaulipas.
APHIS confirms a New World screwworm case in a 22-month-old bovine transported from Veracruz to a feedlot in Nuevo León.
New website centralizing New World screwworm information across the federal government.
This facility will increase the range of sterile fly release and bolster preparedness for New World screwworm.
Federal government will cut the bureaucracy to support the dairy industry, focused on tougher measures to stop major animal disease problems and improve labor availability.
NWS Response Playbook developed as a resource to help animal health officials and responders manage and adapt their response if New World screwworm is found in the U.S.
Secretary of Ag Rollins announces new case of New World screwworm 170 miles from southern border.
“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,” says Dr. Christopher Lee.
Historically, colder temperatures have played a crucial role in controlling New World screwworm’s geographical spread.
FDA conditionally approves first drug for prevention and treatment of NWS infestations in cattle.
U.S. Department of Energy’s National Nuclear Security Administration’s is partnering with Texas A&M University to advance the sterile fly technique to halt NWS reproduction.
With New World screwworm within 70 miles of the U.S.-Mexico border, the livestock industry is on high alert. USDA continues to fight the northward spread of the parasite while debate continues on the border closure.
USDA says this is now the northernmost detection of NWS during this outbreak, and the one most threatening to the American cattle and livestock industry.
New World screwworm was essentially eradicated in the U.S. in 1966, but the persistent pest has rebounded through considerable geography in the past year, prompting the closure of the U.S./Mexico border to cattle in recent months.
Mexico reports 53% increase in NWS cases since July.