The U.S. Department of Health and Human Services has confirmed the nation’s first travel-associated human infection with New World screwworm, a flesh-eating fly larva previously eradicated from the country. The patient, a resident of Maryland, was diagnosed on 4 August after returning from Central America and has since recovered. Federal and state officials said no further human or animal cases have been detected and assessed the overall public-health risk as very low. The Centers for Disease Control and Prevention and Maryland health authorities are tracing the patient’s contacts and advising clinicians to consider the parasite—scientifically known as Cochliomyia hominivorax—in travellers with non-healing wounds. Sources differ on the exposure site, citing either Guatemala or El Salvador, both of which are experiencing livestock outbreaks. Although human infections are rare, the screwworm poses a serious economic threat to cattle producers because its larvae burrow into living tissue of warm-blooded animals. The U.S. Department of Agriculture has halted live-animal imports from Mexico, where the pest is advancing north, and is building a $750 million sterile-fly production facility in Texas to prevent re-establishment of the species. Industry analysts estimate a full-scale outbreak in Texas alone could cost ranchers roughly $1.8 billion. Livestock futures briefly softened after news of the Maryland case, underscoring market sensitivity to any sign the parasite might breach long-standing eradication barriers. Federal agencies are expanding surveillance at ports of entry and urging travellers to outbreak areas to keep wounds covered and use insect repellent. Officials emphasized that early detection and rapid removal of larvae remain effective treatments and that current safeguards are designed to protect both public health and the U.S. food supply.