A new case of New World screwworm (NWS) has been confirmed in Sabinas Hidalgo, Nuevo León, Mexico—just 70 miles from the U.S. border. Mexico’s animal health agency, SENASICA, reported the detection in an 8-month-old cow. The animal had recently been moved from southern Mexico, where NWS cases remain active.
Because this is the northernmost detection in the current outbreak, the risk to U.S. cattle herds has increased. Sabinas Hidalgo also sits on a key trade route linking Monterrey to Laredo, Texas, one of the busiest livestock and goods corridors in the world.
In response, U.S. Agriculture Secretary Brooke L. Rollins called the situation “a national security priority.” She emphasized that USDA will take decisive action to defend the livestock industry and the nation’s food supply. “We will not rely on Mexico to defend our industry, our food supply, or our way of life,” Rollins said.
Border Measures and Monitoring
As a result of this detection, U.S. ports remain closed to imports of cattle, bison, and horses from Mexico. At the same time, USDA and Mexican authorities are expanding surveillance. Nearly 8,000 traps are active across Texas, Arizona, and New Mexico. So far, more than 13,000 samples have been tested, and no NWS flies have been found in the U.S.
Looking ahead, authorities are considering sterile fly releases in Nuevo León to help contain the outbreak. Currently, USDA disperses about 100 million sterile flies per week in Mexico. These efforts are designed to push the pest farther south and prevent it from entering the United States.
USDA’s Five-Pronged Plan
To strengthen its defense, USDA is advancing a five-pronged plan:
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Innovation: The agency has invested $100 million in genetic tools, new sterilization methods, and advanced traps.
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Border Defense: New sterile fly facilities are under construction in Texas, with capacity to release hundreds of millions each week.
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Surveillance: Trap networks and audits of Mexico’s control measures are being expanded.
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Education: USDA is offering training, webinars, and outreach materials to producers and veterinarians.
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International Coordination: The agency continues joint planning with Mexico and supports more staff and equipment in high-risk regions.
Coordinated National Response
In addition, several U.S. agencies are supporting USDA’s efforts. The CDC is leading human health monitoring, while FDA has authorized emergency veterinary drugs. Homeland Security is training border staff to recognize NWS. Meanwhile, the Department of Energy, Interior, EPA, and State are also engaged. Together, these agencies are working under a One Health framework to contain and eventually eradicate the pest.
What Producers and Residents Should Watch
NWS larvae infest wounds in livestock, pets, and wildlife. They feed on living tissue and can cause severe damage if untreated. Therefore, producers should look for enlarging wounds, visible maggots, and unusual animal discomfort.
If NWS is suspected in livestock or pets, USDA urges immediate contact with a state animal health official or USDA veterinarian. Although rare, the parasite can also infect people. In that case, any suspicious lesion should be treated right away by a healthcare provider.
For more information and resources, producers can visit the USDA APHIS website.
