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First US horse case of screwworm detected in Texas border county

By Thomson Reuters Sep 10, 2026 | 7:31 PM

Sept 10 (Reuters) – The first horse in the United States to be infected with New World screwworm has been detected in southern Texas ​near the Mexican border, data from the U.S. ‌Department of Agriculture showed.

The case of the flesh-eating parasite was confirmed on Wednesday in Presidio County, showed the USDA website, after months of infestation of U.S. cattle that has raised ‌alarms ​about how to control the spread ⁠of the pest.

The Texas ⁠Animal Health Commission, which had detected the case, on Wednesday issued an order banning the movement of warm-blooded animals outside a designated “infested” zone within Presidio ​and Jeff Davis counties.

A previous screwworm outbreak killed thousands of animals in the U.S. before the ⁠pest was declared eradicated in ⁠the 1960s.

In Texas, where authorities confirmed the ​first new U.S. animal cases this year, experts estimate ​a widespread outbreak could cost the economy up ‌to $1.8 billion.

Reuters reported last week on growing concerns that smuggled animals, including horses, could be possible hosts for New World screwworm. The USDA and Texas authorities did not ⁠address the origin of the affected horse.

The U.S. Equestrian Federation, which organizes the U.S. Equestrian Open, said the newly ⁠detected infestation occurred ‌in the hind limb of a ⁠working ranch horse, without providing further details.

It ​urged ‌horse owners to regularly inspect their ​horses.

“We encourage ⁠every horse owner to help protect their horses and the broader equine community by practicing good wound care, fly control, and biosecurity,” the organization said in a statement.

(Reporting by Cassandra Garrison and Daina Beth Solomon; editing ​by Lincoln Feast.)