On September 21, 2025, Mexico’s National Service of Agro-Alimentary Health, Safety, and Quality (SENASICA) confirmed a new case of New World screwworm (NWS) in Sabinas Hidalgo, Nuevo León—less than 70 miles from the U.S.-Mexico border. According to SENASICA and the U.S. Department of Agriculture (USDA), this is the northernmost detection of NWS during the current outbreak, and it poses a significant threat to the American cattle and livestock industry. The case’s proximity to the border has sent ripples of concern through agricultural communities on both sides, especially given Sabinas Hidalgo’s location near the major highway connecting Monterrey, Nuevo León, to Laredo, Texas—one of the world’s busiest commercial thoroughfares.
The affected animal was an 8-month-old cow recently moved to a certified feedlot in Nuevo León from a region in southern Mexico with known active NWS cases. This movement highlights a crucial vulnerability in the livestock supply chain, as the USDA stresses the “non-negotiable need for Mexico to fully implement and comply with the U.S.–Mexico Joint Action Plan for NWS in Mexico.” The previous northernmost detection was reported approximately 370 miles farther south on July 9, 2025, in Veracruz, illustrating just how quickly the threat has advanced northward.
In a statement underscoring the urgency of the situation, U.S. Secretary of Agriculture Brooke L. Rollins declared, “Protecting the United States from NWS is non-negotiable and a top priority of the Trump Administration. 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. Nevertheless, American ranchers and families should know that we will not rely on Mexico to defend our industry, our food supply, or our way of life. We are firmly executing our five-pronged plan and will take decisive action to protect our borders, even in the absence of cooperation. Furthermore, we will pursue aggressive measures against anyone who harms American livestock.”
As of September 22, 2025, U.S. ports remain closed to imports of cattle, bison, and horses from Mexico—a measure implemented to prevent the spread of NWS into the United States. Since July, the USDA, in collaboration with Mexican authorities, has been actively monitoring nearly 8,000 traps across Texas, Arizona, and New Mexico. Over 13,000 screening samples have been submitted, with no NWS flies detected so far, according to USDA reports. Nevertheless, the USDA is analyzing all new information related to the recent case in Nuevo León and stands ready to release sterile flies in the region if necessary.
USDA’s aggressive response is built on a comprehensive, five-pronged strategy. First, the agency is investing $100 million in breakthrough technologies through the NWS Grand Challenge, a program designed to enhance sterile fly production and develop innovative tools such as advanced traps, lures, and therapeutics. The USDA is also exploring and validating new technologies—including e-beam and x-ray sterilization, genetically engineered flies, and modular sterilization facilities—through public listening sessions and ongoing evaluations.
Second, the USDA is bolstering border protections. Construction has already begun on an $8.5 million sterile fly dispersal facility at Moore Air Force Base in Edinburg, Texas. Expected to be substantially complete by the end of 2025, this facility will be capable of dispersing up to 100 million sterile flies per week. In partnership with the U.S. Army Corps of Engineers, planning is also underway for a domestic sterile fly production facility in Southern Texas, which could produce up to 300 million sterile flies weekly.
Third, the USDA is strengthening surveillance and detection efforts. Alongside Mexican authorities, the agency continues to monitor nearly 8,000 traps across the southern U.S. border states, and it is dispersing 100 million sterile flies per week in Mexico, sourced from the COPEG facility in Panama. The USDA is also supporting Mexico’s renovation of a production facility in Metapa, which is expected to yield an additional 60–100 million sterile flies per week.
Fourth, public awareness and education are being ramped up. The Animal and Plant Health Inspection Service (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 identification cards and alerts—are being distributed along the U.S.–Mexico border, and APHIS has held over 50 stakeholder meetings to expand outreach efforts.
Fifth, the USDA is coordinating closely with Mexico and international partners. Following detections in Oaxaca and Veracruz, the USDA closed southern ports of entry to livestock trade after a case was reported 370 miles from the U.S. border. The agency conducts monthly audits of Mexico’s NWS response and is helping to develop a risk-based trapping plan, especially in Veracruz and along the border. Mexico currently deploys traps in high-risk areas with USDA support, and the USDA is backing the hiring of over 200 surge staff for trapping and animal movement control in Mexico. SENASICA has also launched a dashboard tracking NWS cases across Mexico, significantly enhancing USDA’s ability to monitor the situation and deliver more effective operational responses in coordination with Mexican authorities.
What’s more, the USDA’s response is characterized by unprecedented interagency collaboration. The Centers for Disease Control and Prevention (CDC) is leading human health surveillance and response, providing diagnostic support, educating healthcare providers, and coordinating One Health efforts across federal, state, and international partners. The Food and Drug Administration (FDA) is ensuring veterinarians, farmers, and animal health officials have timely access to tools needed to protect pets, livestock, and the nation’s food supply by authorizing emergency use of certain animal drugs to treat or prevent NWS infestations. The Department of the Interior (DOI) is ensuring wildlife surveillance and environmental compliance, particularly on federal lands, while the Department of Energy (DoE) is exploring and validating new sterilization technologies. The Department of Homeland Security (DHS) is supporting surveillance, intelligence sharing, and emergency planning—including training Customs and Border Protection and Immigration and Customs Enforcement personnel to identify and respond to NWS cases. The Environmental Protection Agency (EPA) is expediting pesticide approvals and supporting emergency exemptions, and the Department of State (DoS) is leading diplomatic engagement to align technical assistance and deliver consistent messaging.
USDA officials are also urging vigilance among residents along the southern border. As reported by USDA communications, “Look for draining or enlarging wounds and signs of discomfort. 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.” Though NWS infestations are rare in humans, the USDA advises anyone noticing a suspicious lesion or suspecting infection to seek immediate medical attention.
With ports closed, surveillance heightened, and new technologies in the pipeline, the U.S. government is moving swiftly to contain the threat and safeguard the American food supply. As Secretary Rollins put it, “This is only the beginning with many more announcements coming this week as USDA restores American strength, protects food security, and supports America’s ranchers and farmers.” The coming weeks will be crucial as authorities on both sides of the border race to outpace a pest that, if left unchecked, could have devastating consequences for North American agriculture.