Mexico activates emergency controls after new screwworm case near U.S. border

MEXICO CITY — Mexico activated emergency controls Monday after detecting a new case of New World screwworm in cattle in the northern border state of Nuevo León, the closest case to the U.S. border since the outbreak began last year.

The affected animal, found in the town of Sabinas Hidalgo, came from Veracruz, Mexico's National Health for Food Safety and Food Quality Service said. The last case was reported July 9 in Veracruz, prompting Washington to suspend imports of live Mexican cattle.

The parasite, a larva of the Cochliomyia hominivorax fly, attacks warm-blooded animals, including humans.

Mexico has reported more than 500 active cases in cattle across southern states. The cattle-import ban has spelled trouble for the government, which has been trying to offset the brunt of tariff threats in recent months. If the ban stays in place through the year, Mexico’s ranching federation estimates losses up to $400 million.

Mexico's Agriculture Secretary Julio Berdegué said in a post on X that Mexico is 'controlling the isolated case of screwworm in Nuevo León,' under measures to fight the pest agreed with the U.S. in August. U.S. Agriculture Secretary Brooke Rollins said Washington will take 'decisive measures to protect our borders, even in the absence of cooperation' and said imports on Mexican cattle, bison and horses will remain suspended.

Authorities emphasized that the response remains under close surveillance, with health and agricultural agencies coordinating across borders to prevent further spread while supporting affected ranchers.