First Human Case of ‘Horrific’ Flesh-Eating Parasite Detected in the U.S.

The first case of the “horrific” flesh-eating New World screwworm affecting a human has been detected in the United States.

On Monday, Aug. 25, the United States Department of Health and Human Services (HHS) confirmed to Reuters that a person in Maryland has been affected by the painful parasite. The parasite has been posing a threat to the U.S. cattle industry for the first time since the 1960s.

Department spokesman Andrew G. Nixon told the outlet that the case had been detected in a person who had recently traveled to El Salvador and was being investigated by the Maryland Department of Health and the U.S. Centers for Disease Control and Prevention. According to Reuters, the case was confirmed by the CDC as New World screwworm on Aug. 4, Nixon said.

“The risk to public health in the United States from this introduction is very low,” he said in a statement shared with Reuters.

His statement, also shared with Axios, read: “This is the first human case of travel-associated New World screwworm myiasis (parasitic infestation of fly larvae) from an outbreak-affected country identified in the United States.”

The New World screwworm, a type of fly, has been moving north from South America in recent years.

To reproduce, the female fly lays its eggs on “warm-bodied animals,” per Reuters. The outlet reported that the flies “rarely” affect humans, adding that their larvae are more typically found in livestock such as cattle.

Colin Woodall, CEO of the National Cattlemen’s Beef Association, told NPR. that “the [fly] larva does exactly what the name would suggest. It screws or bores into the flesh of our cattle and, in essence, eats the animal from the inside out. It is a horrific parasite.”

The CDC addressed the infestation, saying that it can be “very painful” and that maggots [the fly larvae] can be seen or felt around infection sites. The flies typically lay their eggs near exposed wounds. However, they can also affect a person’s nose, eyes and mouth.

Medical professionals are needed to “remove the larvae,” with the CDC reporting that is accomplished “sometimes through surgery.”

Reuters had previously reported that a person in Maryland had been affected by the parasite after traveling to Guatemala. It is unclear if this is the same person.

The Department of Health and Human Services directed Axios’ questions about the patient to the Maryland Department of Health.

Though painful, the parasitic infection can normally be treated and is not fatal. However, it does pose a serious risk if left untreated.

The U.S. Department of Agriculture recently announced plans to counteract the threat of New World screwworms.

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In an Aug. 15 press release, the organization confirmed that Secretary of Agriculture Brooke L. Rollins reiterated that the U.S. would invest in the creation of sterile male screwworms, which can be released in the wild.

NPR noted that female screwworms only mate once in their lifespan so this measure will help reduce the population and the threat it poses.

The technique was utilized by the U.S. in the ’60s, which is the last time that the fly was a threat to the country.

It is now one part of a “five-pronged plan” previously announced by the organization in June 2025.

PEOPLE has contacted the Maryland Department of Health, the U.S. Department of Health and Human Services and the U.S. Department of Agriculture for additional comment.