Flesh-eating parasite found in Texas cattle has USDA on high alert

A threat to livestock has re-emerged in South Texas and has prompted a significant response from state officials and food safety authorities in the Trump administration.

On Wednesday, the U.S. Department of Agriculture flagged a potential South Texas case of New World screwworm, a flesh-eating parasite that is considered a real threat to livestock.

'These eggs hatch into dangerous parasitic larvae, or maggots, which burrow or "screw" into flesh with sharp mouth hooks.'

The USDA confirmed that a sample has been taken to the USDA's National Veterinary Services Laboratories in Ames, lowa, for "confirmatory testing."

The agency confirmed that it is monitoring the situation on the ground in coordination with local partners.

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The New World screwworm fly is a "devastating pest" whose larvae feed on the living tissue of warm-blooded animals, according to a USDA fact sheet available on a website page dedicated to screwworm information. A screwworm is roughly the size of a common house fly.

New World screwworm "flies lay eggs in open wounds or orifices of live tissue. These eggs hatch into dangerous parasitic larvae, or maggots, which burrow or 'screw' into flesh with sharp mouth hooks. NWS primarily infest livestock, but can also affect any warm-blooded animal, including wildlife, pets, humans, and birds," according to a Texas Animal Health Commission document.

The screwworm fly thrives in warm, humid environments, making the national spread of screwworm unlikely.

On Wednesday night, Secretary of Agriculture Brooke Rollins announced that the tests at the laboratory in Iowa confirmed the detection of New World screwworm. She added that it was found in a "3 week old bovine in Zavala County, Texas."

In another post, Rollins assured the public that "our food supply is 100% safe. This potential New World Screwworm detection is being fully contained and is not a harm to the American food supply or consumer safety."

She added that a return of the parasite was expected last year, according to available predictions: "All models showed NWS coming to the U.S. last summer/early fall — so a big thank you to our partners across the industry and local, state and the entire Trump administration for unprecedented action that gave us almost an extra year to prepare for this moment."

The extra time bought by those monitoring the situation may prove crucial in an already precarious moment for the beef industry.

According to an analysis of the USDA's annual report on U.S. cattle inventory released on January 30, 2026, the cattle herd stands at 86.2 million head, its lowest point in 75 years. Beef prices have already been on the rise month over month for the past year with little relief in sight, and any drop in supply could drive them even higher.

Rollins encouraged all farmers to follow movement restrictions and treatment guidance provided by the Texas Animal Health Commission.

The Texas Animal Health Commission published a press release on Wednesday, stating that the agency has been preparing for a resurgence of NWS cases for "over two years" since "northward progression from Central America was observed in 2023."

The U.S. government has historically had success eradicating the parasite and continuously pushing cases farther southward. The USDA, in fact, "declared the United States free of indigenous screwworms as early as 1966," despite a severe outbreak with 90,000 cases in Texas alone by 1972.

The best method of stopping the spread of NWS is the mass release of sterile flies into the region in which cases are found. Flies are sterilized by being irradiated with gamma rays before being released into the area.

In April, the USDA and U.S. Army Corps of Engineers broke ground on an $8.5 million sterile fly production facility at Moore Air Base in Edinburg, Texas. The initial facility is expected to be operational late 2027 with the production of 100 million sterile flies per week. The project will be scaled further to increase the production to 300 million flies per week in an effort to bolster the United States' domestic strategy against the screwworm.

Rollins reportedly called the response an "all of Trump administration effort," according to CNN.

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