Mexico’s National Service of Agro-Alimentary Health, Safety, and Quality (SENASICA) recently confirmed a new case of New World screwworm (NWS) in Sabinas Hidalgo, Nuevo León, less than 70 miles from the U.S.-Mexico border. This detection marks the northernmost occurrence in the ongoing outbreak and poses the greatest threat yet to the American cattle and livestock industry. The affected cow, an eight-month-old recently moved from a region with known active NWS cases, highlights the risks associated with animal movement and the importance of implementing the U.S.–Mexico Joint Action Plan for NWS.
The U.S. Department of Agriculture (USDA) has emphasized that protecting American livestock is a top national security priority. Ports of entry remain closed to cattle, bison, and horses from Mexico, while USDA and Mexican authorities continue intensive monitoring and surveillance, deploying nearly 8,000 traps across Texas, Arizona, and New Mexico, and analyzing over 13,000 samples to date. Sterile fly releases are being planned and executed to curb the spread of NWS, and additional measures are being developed to rebuild the U.S. cattle supply.
USDA has implemented a comprehensive five-pronged plan to combat NWS. Investments under the NWS Grand Challenge aim to enhance sterile fly production and develop advanced detection tools, including e-beam and x-ray sterilization and genetically engineered flies. A domestic sterile fly dispersal facility is under construction in Edinburg, Texas, with additional production capacity planned for southern Texas. The department continues to support Mexico’s renovation of its Metapa production facility, which will increase sterile fly output.
Surveillance, detection, and public awareness are key components of the response. USDA, alongside APHIS, has distributed educational materials, conducted over 50 stakeholder meetings, and continues training federal, state, Tribal, and veterinary partners. Coordination with Mexican authorities, monthly audits, and deployment of over 200 surge staff are enhancing the border response and ensuring compliance with trapping and animal movement controls.
A multi-agency U.S. response supports the USDA’s efforts. CDC leads human health surveillance and diagnostics, FDA provides emergency authorization for veterinary treatments, DOI ensures wildlife surveillance, DoE validates sterilization technologies, DHS supports border and emergency operations, EPA expedites pesticide approvals, and DoS coordinates diplomatic engagement. These efforts are unified under the U.S. One Health Coordination Unit for NWS, co-led by USDA, CDC, and DOI, focusing on early detection, rapid containment, and long-term eradication.
USDA urges residents near the southern border to monitor pets and livestock for NWS signs, including draining wounds or the presence of larvae, and to report suspected cases immediately. Human infections are rare, but anyone with suspicious lesions should seek prompt medical attention. The coordinated U.S. and international response aims to protect livestock, safeguard food security, and prevent further spread of this dangerous pest.
