First Travel-Associated Human Screwworm Case Confirmed in the U.S.

August 26, 2025, Maryland - U.S. health authorities have confirmed the nation’s first travel-associated human infection with New World screwworm, a flesh-eating parasite, in a Maryland resident returning from El Salvador.

The U.S. Department of Health and Human Services (HHS) announced that the case was confirmed on August 4 by the Centers for Disease Control and Prevention (CDC) in collaboration with the Maryland Department of Health. The patient has fully recovered, and there is no evidence of transmission to other people or animals.

New World screwworm is the larval stage of the fly Cochliomyia hominivorax. Female flies lay eggs in open wounds or body openings, and the hatched larvae burrow into living tissue, feeding on flesh. If untreated, infestations can be fatal in both animals and humans. However, human cases remain extremely rare, and the risk to public health in the United States is considered very low.

Livestock industry officials and veterinarians have expressed concern over the parasite’s northward spread from Central America, where outbreaks have devastated cattle herds. In response, the USDA is working to establish new sterile-fly production facilities aimed at curbing potential outbreaks among livestock near the southern border.

Public health experts emphasize that travelers to regions with known screwworm activity should avoid untreated wounds and seek prompt medical attention for any unexplained sores or foul-smelling discharge. Treatment involves surgical removal of larvae and thorough wound disinfection.

• Reporting by Reuters and The Times of India.