As the livestock industry manages its way through H5N1, the recent confirmation of New World screwworm (NWS) in Sabinas Hidalgo, Nuevo León, is just 70 miles from the U.S.-Mexico border. This marks the northernmost detection of this parasite in decades and constitutes the next big challenge for the health of the industry. This development poses a serious threat to the U.S. cattle and dairy industries, which have been screwworm-free since the 1960s thanks to aggressive eradication programs.

Why This Matters

The screwworm is a parasitic fly whose larvae infest open wounds in warm-blooded animals, causing severe tissue damage, weight loss, and, if untreated, death. For dairy and beef producers, an outbreak could mean:

• An animal health crisis requiring costly treatment and increased veterinary oversight.
• Trade disruptions, as the USDA (United States Department of Agriculture) has already suspended imports of live cattle, bison, and horses from Mexico to prevent the spread. 
• Market volatility, with tighter cattle supply and rising feed costs adding pressure to already stressed supply chains. The rising cost of beef is less related to inflationary effects than it is to drought-response and low supplies. An animal health emergency will not help the situation, to say the least.

Current Response

The USDA and APHIS (Animal and Plant Health Inspection Service) are implementing a five-pronged containment strategy, including sterile fly releases and expanded surveillance across Texas, Arizona, and New Mexico. Over 13,000 screening samples have been tested with no U.S. detections so far. However, the proximity of this latest case underscores the urgency for vigilance. 

What Producers Should Do

• Monitor herds closely for signs of screwworm infestation—particularly in fresh wounds.
• Report suspected cases immediately to state or federal animal health officials. We have seen in some states how prompt action has helped curtail H5N1.
• Stay informed: Industry groups like NMPF and IDFA are hosting webinars on preparedness, early detection, and reporting protocols. 

The Bigger Picture

This outbreak is not just a veterinary issue—it’s a national security and food supply concern. As USDA Secretary Brooke Rollins stated, protecting U.S. livestock from NWS is “non-negotiable and a top priority.”