The U.S. Department of Health and Human Services has confirmed the nation’s first travel-associated human case of New World screwworm in decades. The infection was identified in a Maryland resident who returned from Central America and was laboratory-confirmed by the Centers for Disease Control and Prevention on Aug. 4. A spokesperson said the risk to public health is “very low,” and no U.S. animal cases have been reported this year. Screwworms are parasitic flies whose larvae burrow into living tissue and can be fatal to livestock if untreated. Their re-emergence on U.S. soil comes as outbreaks advance north from Central America and southern Mexico, unnerving ranchers already grappling with record-high cattle prices and the smallest U.S. herd in seven decades. Industry groups warn that even a limited outbreak could disrupt beef and cattle futures. The USDA estimates a screwworm infestation could cost Texas alone about $1.8 billion in livestock losses, labor and medication. Agriculture Secretary Brooke Rollins, under fire for the pace of preventive measures, last week unveiled plans for a sterile-fly production facility at Moore Air Force Base near Edinburg, Texas, modeled on programs that eradicated the pest from the United States in the 1960s.