US cattle industry hit by parasite outbreak, first case since 1966

Veterinary officials confirmed the detection of the New World screw‑worm fly in a calf in La Pryor, Texas, marking the first US case since 1966. The Agriculture Department imposed a 20‑kilometre quarantine around the site to halt spread. The parasite’s larvae feed on the tissue of warm‑blooded animals, threatening an industry already facing its lowest cattle inventory in 75 years.

The announcement triggered a sell‑off in livestock futures on the Chicago Mercantile Exchange and pulled down the share prices of major meat processors such as Tyson Foods and JBS. Experts estimate potential economic losses for Texas ranchers of up to $1.8 billion. The fly has been moving northward from Central America, with more than 27 000 cases reported in Mexico since November 2024, prompting the United States to keep its cattle import border with Mexico closed for over a year.

To contain the infestation, Agriculture Secretary Brooke Rollins is re‑introducing sterile‑fly releases – a technique that successfully eradicated the pest in the 1960s. The method involves mass‑rearing male flies, sterilising them, and releasing them to out‑compete wild males, thereby suppressing the population. Human health risk from the parasite is considered low.