Texas screwworm found 300 miles from first case. Should Florida worry?

The New World screwworm parasite has been confirmed in four Texas counties and Lea County, New Mexico, according to the U.S. Department of Agriculture (USDA). The latest cases include a calf in La Salle County, Texas, a goat in Gillespie County, Texas, and a dog in Lea County, New Mexico, which tested positive on June 8. This marks the first detections in the U.S. since a 2016 Florida outbreak, with the New Mexico case involving a dog that had recently traveled from Mexico, suggesting possible travel-related transmission. The parasite, which infests open wounds in mammals—including livestock, pets, and humans—was eradicated from the U.S. decades ago through federal eradication programs. However, its recent resurgence has prompted heightened surveillance, as the USDA investigates whether the spread is localized or expanding beyond border regions. The parasite’s inland detection complicates efforts to contain it, as infected animals may move undetected. Canada has temporarily halted the import of Texas livestock due to the outbreak, citing biosecurity risks. The USDA maintains that the threat to the U.S. food supply remains low, as affected animals would be identified during inspections and prevented from entering commerce. Still, the cases raise concerns about the effectiveness of current monitoring, especially after federal funding for Central American screwworm surveillance was cut in 2025. The USDA confirmed two initial cases in Zavala County, Texas, on June 3 and 5, before expanding to other regions. Epidemiological investigations are ongoing, though no direct link has been established between the funding cuts and the Texas outbreak. Experts had previously warned that reduced surveillance in Central America could increase the risk of screwworm reaching North America, where it had been successfully eradicated through sterile-fly release programs.