Flesh-eating screwworm hits United States, threatens ranchers, cattle

“We are treating the confirmed case of New World Screwworm on a Texas cattle ranch with the utmost seriousness and are responding aggressively alongside our state partners, TAHC (Texas Animal Health Commission),” she wrote on X.

“USDA's proactive actions bought us nearly a year to prepare, as models had projected New World Screwworm would reach the United States by the summer of 2025. That preparation allowed us to move immediately when this case was detected.”

Rollins went on to reveal how the parasite had reached the southern state and how the administration planned to curb the outbreak. “After years of unchecked spread through Central and South America, this devastating pest has now reached the United States. The Trump Administration and USDA acted swiftly, activating our New World Screwworm Response Playbook, establishing quarantines and movement controls, accelerating sterile fly releases, expanding border trapping, and intensifying livestock and wildlife surveillance,” the secretary explained.

“We are using every tool available, in partnership with states, ranchers, and wildlife officials, to eradicate this pest before it can spread and threaten American cattle producers.”

Screwworms are the parasitic larvae of the Cochliomyia hominivorax fly. The female flies lay their eggs in the membranes of warm-blooded animals, and the larvae use tiny hooks in their mouths to eat the flesh of their victims. If left untreated, a cow can die from the infestation in just a few weeks. It is largely non-lethal to humans.

The USDA stressed that "The US food supply is safe. Screwworms do not infest meat, fruits, vegetables, or other food sources. USDA’s Food Safety and Inspection Service (FSIS) ensures that the nation’s commercial supply of meat, poultry, and egg products is safe and properly labeled. Under the Federal Meat Inspection Act (FMIA), FSIS inspection personnel must inspect all eligible animal species unless they are exempt or covered by a state inspection program."

This is hardly the first time concerns about screwworms have been raised in recent memory. In 2024, an outbreak was discovered in southern Mexico. A shutdown of the livestock trade was ordered at the southern border in July following the detection of the parasite in Mexico.