A possible case of New World screwworm (NWS) has been detected in South Texas, with samples from two calves on a cattle ranch in La Pryor sent to a federal laboratory for confirmation, according to the USDA and Texas officials.

The samples were collected on Tuesday in Zavala County, roughly 100 miles southwest of San Antonio, and forwarded to the USDA’s National Veterinary Services Laboratories in Ames, Iowa. The USDA said a case “may have been detected” and that updates would be provided once results are available. Response teams have already been deployed to the area.

New World screwworm is a parasitic fly whose larvae infest open wounds on warm-blooded animals, including cattle, wildlife, pets, and occasionally humans, feeding on living tissue and potentially causing severe injury or death if left untreated. The pest was eradicated from the United States decades ago through a sterile insect release program, but has been advancing northward from South America through Central America and Mexico in recent years.

Governor Greg Abbott’s New World Screwworm Response Team is leading the state’s efforts in coordination with the Texas Animal Health Commission, Texas Parks and Wildlife Department, and federal partners. If confirmed, officials plan to establish an incident command post, expand fly trapping and surveillance, restrict animal movement, and accelerate the release of sterile male flies to eliminate any reproducing population.

The development has raised immediate concerns among Texas ranchers and agricultural leaders about the potential economic impact on the state’s livestock industry if the infestation spreads.