US Resumes Mexican Cattle Imports Amid Lingering Screwworm Outbreak Concerns

The United States began a phased reopening of its border to live cattle imports from Mexico on Monday, ending a year-long ban, even as Mexican authorities work to contain an outbreak of the flesh-eating screwworm parasite in key northern exporting states. The move has prompted concern among some U.S. cattle industry stakeholders about the potential for the pest to spread.

Border Reopens Under Scrutiny

The resumption of trade, which was halted over a year ago to prevent the pest's entry, will initially allow imports through Arizona before expanding to ports in New Mexico. According to the USDA, the reopening is contingent on Mexico’s continued compliance with screwworm-control measures.

The decision comes as the northern Mexican state of Chihuahua has reported 67 confirmed screwworm cases since its first detection in July. Neighboring Sonora reported its first case last week and now has two confirmed cases, according to the report. The parasite has already been detected in Texas and New Mexico, fueling criticism from some U.S. cattle groups and state officials who view the reopening as premature.

Mexico Ramps Up Containment Efforts

In response, Mexico is bolstering its eradication campaign. Mexican Agriculture Minister Columba Lopez stated that authorities would reinforce the dispersal of sterile flies in the affected border states, a key strategy to curb the parasite's reproduction.

Ad

This method, known as the sterile insect technique, involves releasing millions of sterilized flies that mate with wild females, preventing them from producing offspring and gradually reducing the pest population. Mexican officials have also activated emergency surveillance protocols and intensified livestock inspections and movement controls.

Implications for the Cattle Market

The resumption of trade is significant for the North American livestock market, as Mexico is a critical supplier of cattle to U.S. feedlots and ranchers. However, the risk of a wider screwworm infestation poses a substantial economic threat to the domestic U.S. livestock industry.

Both countries are investing in long-term control infrastructure. Mexico recently opened a sterile-fly production plant, while the U.S. is building its own facility in Texas, which is expected to be completed by the spring of 2027.