First Human Case Of Flesh-Eating Parasite Has MD Link

Maryland and federal officials are investigating the first human case of the flesh-eating parasite New World Screwworm detected in the United States, which appears tied to a person who had recently traveled to El Salvador, media reports said.

The case was confirmed as screwworm by the Centers for Disease Control and Prevention and the Maryland Department of Health on Aug. 4.

"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," HHS spokesperson Emily G. Hilliard said in a statement to NBC News.

Reuters cited beef industry sources last week who said the CDC had confirmed a case of NewWorld Screwworm in a person in Maryland who had traveled to the U.S. from Guatemala.

Andrew Nixon, spokesman for the U.S. Department of Health and Human Services, said in a statement to DCNewsNow.com Monday: “CDC, in coordination with the Maryland Department of Health, investigated a confirmed case of travel-associated New World Screwworm in a patient who returned from travel to El Salvador. The case was confirmed by CDC through telediagnosis (i.e., expert review of submitted larvae images) on August 4, 2025. 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. Currently, the risk to public health in the United States from this introduction is very low.”

A source told Reuters state veterinarians had learned about a human case in Maryland during a call last week with the CDC. A spokesperson for the Maryland Department of Health did not immediately respond to requests for comment.

The larva of the New World Screwworm flies feed on the living tissue of animals and livestock. But humans can also become infested by the larva, according to the CDC.

The CDC said screwworm flies will lay eggs in open wounds and body openinga such as the eyes, ears, nose or mouth. It primarily affects livestock and is rare in humans. It does not spread from person to person, and poses a very low risk to the public, according to U.S. health officials.

The parasite has been a larger concern to ranchers, as cattle infestations have been moving northward through Central America and Mexico. The CDC is working with the U.S. Agriculture Department to prevent further spread, officials said.

Symptoms in humans include:

• Unexplained wounds or sores that aren’t healing
• Maggots around or in open wounds, or in your nose, eyes, or mouth
• Wounds or sores on your skin that worsen and/or are painful
• Open sores that are bleeding
• Foul-smelling odor from the infestation site

Government officials have not confirmed any cases of screwworm cases among animals in the U.S. this year, USA Today reported.

The parasite was eliminated from the U.S., Mexico, and much of Central America between 1966 and 2006 through sterile insect release programs and other measures, Newsweek reported. In late 2016, the Florida Keys were the sites of the first New World Screwworm outbreak in the U.S. since 1966.

The Associated Press contributed reporting.