USDA Confirms New World Screwworm Detection in Texas
Published Friday, June 5, 2026
The U.S. Department of Agriculture Animal and Plant Health Inspection Service confirmed on Wednesday the first detected presence of New World screwworm, NWS, within U.S. borders. A 3-week-old calf in Zavala County, Texas, was found to be infected with larvae. Zavala is close to the Mexican border, west of San Antonio. USDA announced it was taking immediate steps to contain and eradicate, and emphasized there are no threats to the U.S. food supply chain at this time. The department’s immediate steps include:
- USDA and Texas officials have formed an incident command team and are deploying response personnel.
- An approximately 12.5-mile radius infested zone will be established, with implementation of quarantines, animal movement controls, animal inspection, enhanced surveillance and as-necessary treatment.
- Aerial and ground release of sterile NWS flies are or will be underway.
- The U.S. food supply remains safe. Screwworms cannot live in meat, fruits, vegetables or other food sources. Any carcasses damaged by NWS would be condemned at slaughter.
- Sterile fly production and dispersal facilities in Mexico and the U.S. are being brought online on an emergency basis with plans for additional sterile fly releases.
Producers should remain alert for unusual, nonhealing, foul-smelling wounds or maggots and report them to their herd veterinarian or local California Department of Food and Agriculture office. Producers should not treat any maggot-infested wound without first consulting with their herd vet. Because of the high risk of umbilicus and surgical sites, it is important to treat navel, castration and dehorning sites thoroughly and promptly. Wounds can be treated with commercially available permethrin pesticides. More information and recommended actions for producers can found here via a CDFA release.
Staff contact: Matthew Viohl, mviohl@cfbf.com.
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