Mexico Confirms Northernmost Case of New World Screwworm, Prompting U.S. Emergency Response

WASHINGTON, D.C. - September 21, 2025 - In a development that has escalated biosecurity concerns across North America, Mexico's National Service of Agro-Alimentary Health, Safety, and Quality (SENASICA) has confirmed a new case of New World screwworm (NWS) in Sabinas Hidalgo, Nuevo León-just 70 miles from the U.S.-Mexico border. This marks the northernmost detection of NWS in the current outbreak and poses a direct threat to the American cattle industry.

Sabinas Hidalgo sits along the heavily trafficked highway connecting Monterrey to Laredo, Texas, a corridor vital to international trade and livestock movement. The proximity of this detection to the U.S. border has triggered an intensified response from the U.S. Department of Agriculture (USDA), which has been leading a national effort to contain and eradicate the pest.

"Protecting the United States from NWS is non-negotiable and a top priority of the Trump Administration," said Secretary of Agriculture Brooke L. Rollins. "We have given Mexico every opportunity and resource to counter NWS since announcing the Bold Plan in June. But American ranchers should know-we will not rely on Mexico to defend our food supply or our way of life. We are executing our five-pronged plan and will take decisive action to protect our borders."

The infected animal-a young cow-had recently been transported from southern Mexico, where active NWS cases are ongoing. This movement highlights the urgent need for Mexico to fully implement the U.S.–Mexico Joint Action Plan, which includes strict controls on livestock movement and enhanced surveillance.

As of now, U.S. ports remain closed to imports of cattle, bison, and horses from Mexico. USDA has confirmed that over 13,000 screening samples from nearly 8,000 traps across Texas, Arizona, and New Mexico have shown no signs of NWS flies. However, the agency is evaluating the situation in Nuevo León and may deploy sterile flies to the region to suppress the outbreak.

USDA is also preparing to unveil a major initiative aimed at rebuilding the American cattle supply. This plan will offer incentives to ranchers and drive a full-scale revitalization of the beef industry, with additional announcements expected in the coming days.

USDA's Five-Pronged National Strategy

Under Secretary Rollins' leadership, USDA has launched a sweeping five-pronged strategy to protect livestock, wildlife, and public health. This whole-of-government response includes:

1. Innovating Toward Eradication

USDA is investing $100 million in the NWS Grand Challenge to accelerate sterile fly production and develop advanced traps, lures, and therapeutics. Technologies under review include e-beam and x-ray sterilization, genetically engineered flies, and modular sterilization facilities.

2. Securing the Border

Construction is underway on a sterile fly dispersal facility at Moore Air Force Base in Edinburg, Texas. This $8.5 million site will be capable of releasing 100 million sterile flies weekly. Plans are also in motion for a domestic production facility in Southern Texas with a projected capacity of 300 million sterile flies per week.

3. Strengthening Surveillance and Detection

USDA continues to monitor traps across the Southwest and is dispersing 100 million sterile flies weekly in Mexico, sourced from the COPEG facility in Panama. Support is being provided to renovate Mexico's Metapa facility, which could add another 60–100 million sterile flies to the effort.

4. Enhancing Public Awareness

APHIS has updated its national disease response strategy and is conducting webinars and training for federal, state, Tribal, and veterinary partners. Outreach materials, including pest ID cards and alerts, are being distributed along the border, and over 50 stakeholder meetings have been held.

5. Coordinating with Mexico and Global Partners

Following earlier detections in Oaxaca and Veracruz, USDA closed southern ports of entry to livestock trade. Monthly audits of Mexico's response are ongoing, and USDA is helping develop risk-based trapping plans. More than 200 surge staff are being hired in Mexico to support trapping and animal movement control.

SENASICA has also launched a dashboard to track NWS cases across Mexico, enhancing USDA's ability to assess risk and coordinate operational responses.

Interagency Collaboration

USDA's response is bolstered by unprecedented collaboration across federal agencies:

• CDC is leading human health surveillance and coordinating One Health efforts.

• FDA has authorized emergency use of animal drugs to treat or prevent NWS infestations.

• DOI is overseeing wildlife surveillance and environmental compliance.

• DoE is validating new sterilization technologies.

• DHS is training border personnel and supporting emergency planning.

• EPA is expediting pesticide approvals and emergency exemptions.

• DoS is coordinating diplomatic engagement and technical assistance.

These efforts are unified under the U.S. One Health Coordination Unit for NWS (U.S. OHCU–NWS), co-led by USDA, CDC, and DOI. The unit is executing a phased strategy focused on early detection, rapid containment, and long-term eradication.

What Residents Can Do

NWS maggots infest warm-blooded animals-including humans-by entering through open wounds and feeding on living tissue. USDA urges residents near the border to inspect pets and livestock for draining wounds, signs of discomfort, and larvae near body openings.

If you suspect an animal is infected, contact your state animal health official or USDA veterinarian immediately. For suspected human cases, seek medical attention without delay.

To learn more about NWS and how to protect your animals, visit the APHIS website.

Based on an original report from the National Beef Wire:

https://www.nationalbeefwire.com/mexico-confirms-case-of-new-world-screwworm-in-nuevo-leon