Mexico Says Screwworm Case Near U.S. Border Contained, No Flies Detected in North

By Cassandra Garrison

MEXICO CITY, Sept. 22 (Reuters) – A confirmed case of an animal infected with the flesh-eating screwworm parasite in Mexico’s northern Nuevo Leon state near the U.S. border was immediately treated to prevent a further outbreak, the Mexican government said Monday.

The country’s agriculture ministry said there was no risk of adult screwworm fly emergence due to the early detection of the infected bovine, which was confirmed on Sunday.

Fly traps in northern Mexico have not detected a single screwworm fly, the statement added.

The screwworm parasite has moved northward through Central America and Mexico, rattling the U.S. cattle industry and prompting the U.S. government to keep its border mostly closed to Mexican cattle imports since May, adding to trade tensions between the two countries.

The U.S. Department of Agriculture first confirmed the case detected less than 70 miles (113 km) from the U.S.-Mexico border in a statement late Sunday, saying it was analyzing the information and “will pursue all options to release sterile flies in this region as necessary.”

The infected animal was in a shipment of 100 animals originating from the Gulf Coast state of Veracruz, Mexico said.

“We are managing an isolated case of screwworm infestation in Nuevo Leon and implementing the measures agreed upon with the U.S. government just over a month ago,” Mexico’s Agriculture Minister Julio Berdegue said Monday in a post on X.

Mexico recorded 5,086 cases of screwworm in animals as of August 17, according to the most recent government data. That was a 53% jump from July.

U.S. cattle ranchers on the southern border contacted by Reuters reacted with little surprise to the case in Nuevo Leon, and many have been preparing for months to deal with the pest.

U.S. health officials confirmed in August a human infection of screwworm in Maryland in a person who had traveled from El Salvador after Reuters exclusively reported on the case.

Mexican President Claudia Sheinbaum said the country was waiting on an assessment by a team of USDA experts that recently visited Mexico.

(Reporting by Cassandra Garrison, additional reporting by Heather Schlitz in Chicago; Editing by Natalia Siniawski and Cynthia Osterman)