La prior: The United States has confirmed the presence of flesh-boring fly larvae in livestock for the first time in six decades. The U.S. Department of Agriculture identified the New World Screwworms in a three-week-old calf in La Prior, Zavala County, Texas, close to the Mexican border. This discovery marks the first instance of this parasite in U.S. livestock since its eradication in the 1960s.
According to Thai News Agency, the larvae were detected in the umbilical wound of the calf, with species samples verified by the National Veterinary Laboratory in Iowa. Agriculture Secretary Brooke Rollins reported that only one case has been identified, with no further infections noted elsewhere. Rollins assured the public that there is no threat to food or meat safety, as these parasites do not target processed meat. While there is a minimal risk of infection to humans and pets through open wounds, the general population remains at low risk.
Government agencies, along with the Texas State Animal Health Commission, have implemented control measures, establishing a 20-kilometer quarantine zone around the detection site. This measure restricts the movement of warm-blooded animals and involves deploying millions of sterile wild flies by air and truck. This method, used successfully in the past, aims to curb the spread by preventing the reproduction of the species, as female flies mate only once.
The New World Screwworms, larvae of the fly species Cochliomyia hominivorax, are known for laying eggs on fresh wounds of warm-blooded animals. The larvae, upon hatching, feed on living tissue, posing a significant threat to livestock and other mammals if untreated. The United States had previously halted live livestock imports from Mexico since May 2025 due to the parasite's rapid spread from Central America. Officials urge farmers to monitor their animals for signs of infection diligently.