New World screwworm (NWS) continues to creep closer to the U.S.-Mexico border. According to Lyndsay Cole, chief of strategic communications NWS directorate for USDA-APHIS, Mexico has reported two new cases in Nuevo León that are about 52 miles away from the border and one was reported Wednesday about 55 miles away in Coahuila.
“There are no cases or suspect cases in the U.S.,” Cole stresses.
New World screwworm is NOT in the U.S. and @USDA continues to deploy proven technology and nationwide outreach to stay ahead of this pest and protect livestock, pets, wildlife, and people.
— USDA Animal and Plant Health Inspection Service (@USDA_APHIS) May 28, 2026
Preparedness starts with awareness, so get the facts: https://t.co/3qu43ITr1j pic.twitter.com/9Kpc3uxCdO
A Narrowing Buffer Zone
There are currently 2,072 active cases of NWS in Mexico. USDA continues to disperse 100 million sterile insects per week in Mexico and along the U.S.-Mexico border and closely evaluates the location and circumstances of each new case. The sterile insect release area, or polygon, is adjusted as needed to maintain broad suppression and help prevent the pest from moving into the U.S.
Early Detection: The Stench of Infestation
As NWS inches closer, 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 the treatable pest contained.
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 NWS is often the first warning sign.
The prevention and treatment playbook is already taking shape. Prevention means fewer wounds, tighter calving windows, stronger parasite programs and more “eyeballs” on cattle, backed up by early reporting and a vet-guided treatment plan.
When cases do occur, today’s toolbox — from prescription pour-ons and emergency-use injectables — can limit the damage, as long as producers know how and when to use each tool.
Border Awareness: CBP Issues Traveler Warnings
U.S. Customs and Border Protection (CBP) announced a public awareness campaign warning the South Texas traveling public about the threat of NWS on May 28. CBP Laredo Field Office developed an informational tearsheet in English and Spanish that advises about the threat of NWS and is distributing the tearsheet at the eight ports of entry from Brownsville to Del Rio, Texas, that comprise the Laredo Field Office area of responsibility.
“We are working to increase public awareness regarding New World screwworm so that the public can help prevent this invasive pest from reaching the U.S. and adversely affecting U.S. livestock and pets,” says Laredo Field Office Field Operations Director Donald R. Kusser. “By distributing these tearsheets and amplifying via social media, we are hoping to bring this message to the widest audience possible.”
NWS Resources
Visit Screwworm.gov for a wide range of stakeholder resources for 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.
Your Next Reads:
- What Products are Available to Prevent and Treat New World Screwworm?
- “Report, Don’t Hide It”: Experts Urge Rapid Action When Suspecting New World Screwworm
- How Will U.S. Producers Maintain Business when New World Screwworm Invades?
- The Smell You’ll Never Forget: A Calf Infested with New World Screwworm
