Mexico’s National Service of Agro-Alimentary Health, Safety, and Quality (SENASICA) confirmed a new case of New World screwworm (NWS) in Sabinas Hidalgo, located in the state of Nuevo León, less than 70 miles from the U.S.-Mexico border on Sept. 21.
USDA reports this is now the northernmost detection of NWS during this outbreak, and the one most threatening to the American cattle and livestock industry. Sabinas Hidalgo is located near one of the most heavily trafficked commercial thoroughfares in the world, the major highway from Monterrey, Nuevo Leon, to Laredo, Texas.
“Protecting the United States from NWS is non-negotiable and a top priority of the Trump Administration,” U.S. Secretary of Agriculture Brooke L. Rollins said in a release. “This is a national security priority. We have given Mexico every opportunity and every resource necessary to counter NWS since announcing the NWS Bold Plan in June 2025.”
Rollins says the U.S. will not rely on Mexico to defend U.S. agriculture.
“We are firmly executing our five-pronged plan and will take decisive action to protect our borders, even in the absence of cooperation,” Rollins said. “Furthermore, we will pursue aggressive measures against anyone who harms American livestock.”
The previous northernmost detection was reported approximately 370 miles farther south on July 9 in Veracruz, USDA reports.
SENASICA preliminary reports indicate the affected animal — an 8-month-old cow — had recently been moved to a certified feedlot in Nuevo León from a region in southern Mexico with known active NWS cases. USDA says this potential link to animal movement underscores the “non-negotiable need for Mexico to fully implement and comply with the U.S.–Mexico Joint Action Plan for NWS in Mexico.” U.S. ports remain closed currently to imports of cattle, bison, and horses from Mexico.
USDA has been actively monitoring nearly 8,000 traps across Texas, Arizona and New Mexico. More than 13,000 screening samples have been submitted to date, with no NWS flies detected. USDA said it will continue to analyze all new information related to the recent case in Nuevo León and will pursue all options to release sterile flies in this region as necessary.
As well, USDA will release a significant plan soon to help rebuild the American cattle supply, incentivizing ranchers and driving a full-scale revitalization of the American beef industry, the release said.
USDA Leads An Aggressive National Response
USDA reports it’s comprehensive strategy includes the following immediate actions:
- Innovating Our Way to Eradication
USDA is investing $100 million in breakthrough technologies through the NWS Grand Challenge. This program will solicit ideas to enhance sterile fly production and develop new tools such as advanced traps, lures and therapeutics. USDA says it’s also exploring and validating technologies like e-beam and x-ray sterilization, genetically engineered flies, and modular sterilization facilities through public listening sessions and ongoing evaluations. - Protecting the U.S. Border
USDA has begun construction on a domestic sterile fly dispersal facility at Moore Air Force Base in Edinburg, Texas. This $8.5 million facility, expected to be mostly complete by the end of 2025, will be capable of dispersing up to 100 million sterile flies per week, USDA says. The U.S. Army Corps of Engineers is working with USDA on plans for for construction of a domestic sterile fly production facility in Southern Texas, with a projected capacity of 300 million sterile flies per week. - Strengthening Surveillance and Detection
USDA has been actively monitoring nearly 8,000 traps across Texas, Arizona and New Mexico since July. To date, more than 13,000 screening samples have been submitted, with no NWS flies detected. USDA continues to disperse 100 million sterile flies per week in Mexico, sourced from the COPEG facility in Panama. In addition, USDA is providing support to Mexico to renovate a production facility in Metapa, which is expected to produce an additional 60–100 million sterile flies. - Enhancing Public Awareness and Education
APHIS has published an updated national disease response strategy and is providing training and webinars for federal, state, Tribal and veterinary partners. Outreach materials, including pest ID cards and alerts, are being distributed along the U.S.–Mexico border. APHIS has held over 50 stakeholder meetings and continues to expand outreach efforts. Coordinating with Mexico and International Partners
Following detections in Oaxaca and Veracruz, USDA closed southern ports of entry to livestock trade after a case was reported 370 miles from the U.S. border. USDA is conducting monthly audits of Mexico’s NWS response and is helping the country develop a more risk-based trapping plan, especially in Veracruz and along the border. Mexico currently deploys traps in high-risk areas, with USDA support.USDA is supporting hiring of over 200 surge staff for trapping and animal movement control in Mexico. As well, SENASICA has launched a dashboard that tracks NWS cases across Mexico. This enhances USDA’s ability to monitor the situation south of the border, better assess risk, and deliver more effective operational responses in coordination with Mexican authorities.
- Unprecedented Interagency Collaboration
Collaborating agencies include: Centers for Disease Control and Prevention, Food and Drug Administration, Department of the Interior, Department of Energy, Department of Homeland Security, Environmental Protection Agency, and the Department of State. This collaboration is guided by the U.S. One Health Coordination Unit for NWS (U.S. OHCU–NWS), co-led by USDA, CDC, and DOI, the release said.
Watch Out for Signs of NWS
NWS maggots most often enter an animal through an open wound and feed on the animal’s living flesh. They can infest livestock and other warm-blooded animals, including people.
USDA urges residents on the southern border to check their pets and livestock for signs of NWS.
“Look for draining or enlarging wounds and signs of discomfort,” USDA said. “Also look for screwworm larvae (maggots) and eggs in or around body openings, such as the nose, ears, and genitalia or the navel of newborn animals. If you suspect your animal is infected with screwworm, contact your state animal health official or USDA area veterinarian immediately.”
Although not common in people, if you notice a suspicious lesion on your body or suspect you may have contracted screwworm, seek immediate medical attention.
