U.S. Halts Mexican Livestock Imports Amid Flesh-Eating Parasite Threat

The U.S. suspended all imports of live cattle, horses, and bison from Mexico effective May 11, 2025, after detecting the New World screwworm (NWS) in Oaxaca and Veracruz-700 miles from its border.

Agriculture Secretary Brooke Rollins called the parasitic fly, whose larvae consume living animal tissue, an “existential threat” to the $89 billion U.S. livestock industry.

Mexico’s Agriculture Secretary Julio Berdegue rejected the measure but pledged collaboration to resolve the crisis within 15 days. The NWS, eradicated in the U.S. by 1966 using sterile insect releases, reemerged in Mexican states last November.

Despite a temporary April 2025 agreement allowing U.S. fumigation flights and tariff-free equipment, outbreaks spread northward. Illegal cattle trafficking from Central America worsened containment efforts, with larvae detected in remote farms lacking biosecurity protocols.

The USDA stated the month-to-month suspension aims to prevent a repeat of the 1970s crisis, when Texas alone suffered $283 million in losses.

Mexico’s livestock exports to the U.S. totaled $2.7 billion in 2024, while American ranchers face rising feed costs and quarantine expenses. Colin Woodall of the National Cattlemen’s Beef Association criticized Mexico’s “delayed response” but endorsed the suspension as necessary.

The USDA will inspect and treat stranded livestock at border ports while monitoring Mexico’s eradication progress. Historical data shows NWS can kill adult cattle in two weeks, with larvae infesting wounds or mucous membranes.

Both nations aim to restore trade by mid-June but acknowledge risks from smuggling and climate-driven pest migration. The decision underscores escalating tensions between economic security and cross-border cooperation in managing ecological threats.