First U.S. screwworm case confirmed in South Texas

Key Points:

• The U.S. Department of Agriculture confirmed the first case of New World screwworm in South Texas, identified in a three-week-old calf in Zavala County, posing a threat to the state's $15 billion cattle industry.
• Screwworm larvae infest live flesh of warm mammals, causing severe wounds or death, and had been eradicated in the U.S. since the 1960s but recently re-emerged in Central America and Mexico.
• The USDA has deployed over 8,000 traps and tested tens of thousands of samples and wildlife since early 2025, with this being the first positive detection in the U.S. during this period.
• Efforts to control the spread include shutting down southern border live animal imports, collaborating with Mexico and Panama on sterile fly eradication methods, and establishing new sterile fly production and dispersal facilities.
• Texas officials have expressed frustration with the federal response, urging faster action such as deploying the Screwworm Adult Suppression System, while local leaders pledge to work with agencies to contain the outbreak.