Screwworm Crisis Shuts Down Livestock Border

New Screwworm Cases in Mexico Trigger Livestock Trade Shutdown

To protect U.S. livestock, Agriculture Secretary Brooke Rollins has ordered the closure of all southern border ports to Mexican cattle, bison, and horse imports. This strong action follows a new detection of New World Screwworm (NWS) in Veracruz, Mexico, much farther north than previous detections.

Mexico’s SENASICA agency confirmed a case in Ixhuatlán de Madero, about 160 miles north of Mexico’s current sterile fly control zone. This location is only 370 miles from the U.S. border. It follows earlier reports from Oaxaca and Veracruz in May 2025 that first led to restrictions on livestock imports.

USDA is now holding Mexico accountable for controlling the outbreak. Efforts include strict controls on animal movements, strong surveillance, and use of sterile flies to push the screwworm barrier south. Secretary Rollins emphasized the importance of acting quickly and following science-based methods to stop the pest’s spread.

In June, Secretary Rollins launched a Bold Plan to stop screwworm. This includes strengthening border protection, increasing fly dispersal operations in Mexico, and building better readiness within the U.S. A new sterile fly dispersal center is being built in South Texas. This will be a backup if screwworm is found in the U.S. USDA is also planning to build a domestic sterile fly production facility.

These actions are being taken in close cooperation with Arizona, New Mexico, and Texas. USDA is working with state and local leaders to ensure a united response.

USDA experts will continue traveling to Mexico to monitor how the government there is handling the outbreak. The goal is to ensure proper controls, detection, and response systems are in place.