Health officials confirmed the first human case in the U.S. of the flesh-eating parasite New World screwworm that has been rapidly spreading among cattle in Mexico and Central America.
The U.S. Department of Health and Human Services told multiple outlets in a statement that the case was discovered earlier this month in a patient in Maryland.
The Centers for Disease Control and Prevention and the Maryland Department of Health both confirmed the case to be New World screwworm.
The individual had recently been to El Salvador, so health officials said it is a travel-related case, and the public health risk in the U.S. is very low.
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Fly larvae of New World screwworm infest the tissue or flesh of warm-blooded animals. It mostly happens among livestock, but in rare cases it can infest people, according to the CDC.
Infestations begin when a female screwworm fly lays its eggs in an open wound of a warm-blooded animal or in an opening — like a nose, mouth or eyes. The eggs hatch into larvae, known as maggots, that burrow into the wound to feed on the living flesh. After feeding, the larvae drop to the ground and burrow into the soil before emerging as adult screwworm flies.
Even wounds as small as a tick bite may attract a female screwworm fly, the CDC explained. One female screwworm fly can lay 200 to 300 eggs at one time.
New World screwworm fly infestations do not regularly occur or spread in the U.S. Cases are typically found in South America and the Caribbean, the CDC said, but people who travel to those regions and spend time around livestock, sleep outdoors, or have an open wound are at greater risk of becoming infested.
Symptoms of infestation include seeing maggots around open sores, wounds that do not heal or worsen over time, bleeding from open sores, foul-smelling odor from an infestation site and/or feeling larvae movement in a wound or in your nose, mouth or eyes, according to the CDC.
Just last week, HHS announced a declaration that allowed the U.S. Food and Drug Administration to issue Emergency Use Authorizations for drugs to treat or prevent infestations of New World screwworm in animals.
