New World screwworm resurfaces in US Southwest, prompting statewide response

The U.S. Department of Agriculture confirmed a second case of the flesh‑eating New World screwworm in a one‑month‑old calf in New Mexico, following an earlier detection in a Texas calf. The parasite, previously eradicated from North America in the 1960s, has been spreading northward from Mexico, where thousands of cases have been reported. Experts link the resurgence to illegal cattle smuggling across Central America, a practice that can carry the worm and other diseases such as avian flu and tuberculosis. “Every cow that is being moved illegally has the potential to carry a screwworm and other diseases,” said wildlife ecologist Jeremy Radachowsky.

U.S. and Mexican authorities are expanding sterile‑fly release programs to suppress the pest, while Texas Agriculture Commissioner Sid Miller has pressed for the use of the controversial Screwworm Adult Suppression System (SWASS), a pesticide‑bait technique the USDA says is no longer viable. In Colorado, the Department of Agriculture has activated its response plan, issuing alerts to livestock owners, hosting webinars, and urging prompt reporting of any suspected infestations. The adult flies are larger than houseflies with distinctive orange‑tinted eyes, and the maggot stage can cause severe wounds in animals. Officials warn that an uncontrolled outbreak could cost the beef industry billions of dollars and drive beef prices higher for consumers.