New World Screwworm Outbreak Raises Livestock Concerns but Not Food-Safety Risks

In early June 2026, a three-week-old calf in South Texas tested positive for New World screwworm, the first U.S. case since eradication in 1966. Additional cases in Texas and New Mexico prompted alerts from animal-health agencies and the USDA. The larvae enter open wounds or mucous membranes of warm-blooded animals and feed on living tissue.

Screwworm Not a Food Safety Threat

Female New World screwworm (Cochliomyia hominivorax) lay hundreds of eggs on wounds, eyes or umbilical openings. Eggs hatch in 12–24 hours; larvae burrow into flesh, causing pain, tissue loss and odor. Larvae cannot survive on dead tissue and die if the host perishes before pupation. Adults need temperatures above 20 °F and pupae require daily averages above 46 °F, restricting the fly in colder areas.

Screwworm Not a Food Safety Threat

The Dallas Federal Reserve estimates that unchecked screwworm spread could cause billions of dollars in losses for the southwestern United States through reduced cattle productivity and higher treatment costs. These pressures are expected to raise beef prices as consumers already face record-high meat costs.

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Kansas Department of Agriculture assistant animal health commissioner Dr. Sarah McReynolds and Kansas State University entomologist Cassandra Olds say the outbreak is an animal-health issue, not a food-safety threat. Dr. Jonathan Cammack concurs that meat is safe. Maximillian Seunik, executive director of Screwworm Free Future, emphasizes that price impacts differ from direct food-quality risks. USDA inspectors label suspect carcasses “US Suspect,” prompting veterinary examination; the FDA requires a withdrawal period for treated animals. Kansas’s response uses a “three-legged stool” of surveillance, treatment and movement control. The U.S. declared eradication in 1966 after a sterile-insect program.

Screwworm Not a Food Safety Threat

• “It’s a threat to food, inasmuch as it’s a threat to food prices, but it’s not a threat from the perspective of food quality or the food that you’ll be consuming,” — Maximillian Seunik, Executive Director, Screwworm Free Future

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• “Meat is still safe,” — Dr. Jonathan Cammack, Assistant Professor, Oklahoma State University

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• “This is not a food safety concern, and that’s an important point we want everyone to understand,” — Dr. Sarah McReynolds, Assistant Animal Health Commissioner, Kansas Department of Agriculture

Screwworm Not a Food Safety Threat

• “You may have a straw-colored, sometimes slightly bloody fluid oozing out of the wound, and there’s often a very distinctive, putrid smell,” — Cassandra Olds, Veterinary Entomologist, Kansas State University

Screwworm Not a Food Safety Threat

Kansas officials emphasize a “three-legged stool” of surveillance, treatment and movement control, urging producers to report lesions promptly while permitting animal movement. Texas and New Mexico are distributing educational materials to hunters and producers. Sterile-insect releases and temperature-dependent limits aim to confine the parasite to summer months, with winter “clear-out” periods.

Screwworm Not a Food Safety Threat