USDA confirms two more cases of New World screwworm in the US

The U.S. Department of Agriculture on Monday confirmed two more cases of New World screwworm in Texas, involving a calf in La Salle County and a dog in Andrews County.

The USDA said epidemiological investigations are ongoing in both cases.

New World screwworm is a pest that threatens livestock, pets, wildlife, and, in rare cases, people, the USDA said.

A second case of the flesh-eating parasite was confirmed in Texas by the USDA on Friday, emerging just miles from where the first U.S. detection in decades was reported last week.

AGGRESSIVE, COORDINATED RESPONSE

Screwworms are flies whose females lay eggs in open wounds on warm-blooded animals. Once hatched, larvae burrow into living flesh, feeding on tissue and potentially killing the host if left untreated.

The parasite has been moving north through Mexico for more than a year.

The U.S. has closed its borders to cattle imports for more than a year to stop the parasite spreading into border states. To curb its advance through Mexico, the U.S. has invested millions of dollars in measures such as building sterile fly production facilities, expanding trapping and increased livestock monitoring.

The USDA and the Texas Animal Health Commission (TAHC) said they are leading an aggressive, coordinated response.

A total of 75 people are deployed on the ground, with hundreds more providing laboratory diagnostics, logistics, treatment distribution, air operations, outreach and planning support, the USDA said.

The agency added it is continuing to release sterile flies over and around affected areas.

(Reporting by Anushree Mukherjee, Anjana Anil, and Ashitha Shivaprasad in Bengaluru. Editing by Sriraj Kalluvila and Mark Potter)

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This story was originally published June 8, 2026 at 9:43 AM.