Screwworm comeback tests U.S. livestock defenses

An outbreak of New World screwworm, a flesh-eating parasite that infests warm-blooded animals, has returned to the United States with 15 confirmed cases in Texas and New Mexico, mainly affecting cattle. Officials are deploying sterile flies, expanding surveillance, and tightening border and movement controls to contain it, warning the outbreak could cost billions if it spreads, even as human risk remains low. The situation echoes the historic success of the sterile-insect technique used to eradicate the pest decades ago.