US screwworm cases rise as outbreak spreads beyond initial contamination zones

Dyed screwworm fly pupae are seen as a sterile fly dispersal station is placed by the US Department of Agriculture to combat the spread of the New World screwworm fly on grounds of a ranch near La Pryor, Texas, on 11 June 2026. Photograph: Eric Gay/AP View image in fullscreen Dyed screwworm fly pupae are seen as a sterile fly dispersal station is placed by the US Department of Agriculture to combat the spread of the New World screwworm fly on grounds of a ranch near La Pryor, Texas, on 11 June 2026. Photograph: Eric Gay/AP US screwworm cases rise as outbreak spreads beyond initial contamination zones Twelve animal cases have been confirmed so far among cattle, goats, sheep and a dog in Texas and New Mexico Screwworm cases are rising in the US as the outbreak spreads beyond the initial contamination zones. Twelve animal cases have been confirmed so far, a significant increase from the first case detected in a calf in south Texas on 3 June. The growing number of infections has alarmed agricultural experts, who warn that a wider outbreak could have serious consequences for the Texas beef industry. Of the 12 reported cases, 11 remain active and one is inactive, according to an update issued last Thursday by the US Department of Agriculture’s animal and plant health inspection service. The most recent case was reported on 12 June in Sutton countyin west Texas, where a sheep was discovered with the infection. Other cases have been identified in the Texas counties of Edwards, Tom Green, Gillespie, La Salle and Zavala, as well as in Lea county, New Mexico. Alarm as once-eradicated flesh-eating parasite found in calf in Texas Read more The infected animals include cattle, goats, sheep and one dog. The screwworm is a fly larva that burrows into open wounds on livestock and other warm-blooded animals, feeding on living tissue. For nearly six decades, the parasite was rarely seen in the US after being largely eradicated in the 1970s. However, its re-emergence and rapid spread have raised concerns that the parasite is making a comeback at a time when beef prices are at record highs. USDA officials are urging animal owners to watch for signs of screwworm infection, including draining or enlarging wounds, maggots or egg masses, unusual discomfort, and lesions around the nose, ears, genitals or umbilical area. Suspected cases should be reported immediately to help contain the spread of the parasite, the USDA said. It added that despite the outbreak, the US food supply remains safe, as the screwworm does not infest meat, fruits, vegetables or other fruit products. In a statement last week, Texas’s agriculture commissioner, Sid Miller, warned of the spread, saying: “This should set off alarm bells across the country. Every day we delay gives this pest another opportunity to spread.” Miller called for the deployment of the Screwworm Adult Suppression System (Swass), a USDA-developed program that uses targeted bait to kill fertile adult screwworm flies before they c