Headlines in 1966 spread the word that the New World screwworm had been eradicated from the U.S. Nearly 60 years later, they\u2019re back.<\/p>\n
The New World screwworm is a parasitic fly that lays its eggs in open wounds and body openings such as eyes, ears, nose or mouth, according to the Centers for Disease Control and Prevention (CDC)<\/a>. The eggs grow into parasitic maggots that burrow and feed on living tissue.\u00a0<\/p>\n The CDC estimates one adult female screwworm could lay up to 3,000 eggs in her lifetime.<\/p>\n NC State Veterinary Parasitologist Dr. Andy Moorhead said the screwworm wasn\u2019t something he anticipated seeing come back in his career.\u00a0<\/p>\n \u201cIt essentially crossed over the border from Mexico into Texas,\u201d Moorhead said. \u201cThese maggots are the ones that cause a lot of damage. These maggots don\u2019t eat into dead flesh, they eat into live flesh.\u201d<\/p>\n Texas and New Mexico have reported a combined 43 domestic animal infections as of July 30, 2026. The U.S. Department of Agriculture (USDA) launched an\u00a0online dashboard to monitor the spread of cases<\/a>.\u00a0<\/p>\n The New World screwworm poses the biggest threat to cattle and wildlife in the southwestern United States. The screwworm can also infest human tissue, though infections in humans remain rare. Texas A&M AgriLife Extension Service reports humans make up less than 1% of all infections.\u00a0<\/p>\n Experts studying screwworm infections say they can turn a wound the size of a quarter into one several inches long in a matter of hours.\u00a0<\/p>\n The growing number of cases has prompted an unprecedented response by the federal government.\u00a0<\/p>\n This week, the USDA announced a $25 million investment for an Arizona-based facility aimed at curbing screwworm spread. The agency says the funding \u201cadvances USDA\u2019s aggressive strategy to strengthen sterile fly production and dispersal capacity.\u201d<\/p>\n \u201cThe reason they release sterile males is because the females will only mate once,\u201d Moorhead explained. \u201cIf you have a sterile male and it mates with the female, it\u2019s taken that female out of play and the eggs that the female lays will not develop.\u201d<\/p>\n The USDA now has a dedicated screwworm website<\/a> featuring case updates, response efforts and educational resources.\u00a0<\/p>\n