Health Officials Confirm Human Case Of ‘Flesh-Eating New World Screwworm’ In United States

The Department of Health and Human Services (HHS) said it confirmed a human case of ‘New World screwworm,’ a flesh-eating parasite.

Health officials said the case involved an individual in Maryland who recently traveled to Central America.

“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,” said HHS spokesperson Andrew Nixon in an emailed statement, according to Axios.

Nixon said the risk to public health in the United States remains very low.

Report: A case of the flesh-eating screwworm parasite has been confirmed in Maryland, U.S., in a patient who recently traveled from Guatemala

Via: Reuters pic.twitter.com/1hNYxvvsAn

— The Calvin Coolidge Project (@TheCalvinCooli1) August 25, 2025

Reuters has more:

Earlier, Reuters reported that beef industry sources said last week that the CDC had confirmed a case of New World screwworm in a person in Maryland who had traveled to the United States from Guatemala.

Nixon did not address the discrepancy on the source of the human case.

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

The U.S. government has not confirmed any cases in animals this year.

The differing accounts from the U.S. government and industry sources on the human case are likely to further rattle an industry of cattle ranchers, beef producers and livestock traders already on high alert for potential U.S. infestations as screwworm has moved northward from Central America and southern Mexico.

In May, U.S. Department of Agriculture (USDA) Secretary Brooke Rollins “announced the suspension of live cattle, horse, and bison imports through U.S. ports of entry along the southern border due to the continued and rapid northward spread of New World Screwworm (NWS) in Mexico.”

“NWS has been recently detected in remote farms with minimal cattle movement as far north as Oaxaca and Veracruz, about 700 miles away from the U.S. border,” a press release read.

With the confirmation of a human case, there are fears of possible New World screwworm infestations in U.S. cattle.

The fact that there is a human case of New World Screwworm in the United States confirms our suspicions that there are other cases that the USDA may be covering up

This is so scary https://t.co/vUCAC5Enn4

— Meriwether Farms (@MeriwetherFarms) August 24, 2025

Axios noted:

“Myiasis is a parasitic infestation of fly larvae (maggots) in human tissue,” per an online CDC post. “New World screwworm (NWS) is a species of parasitic flies that can cause myiasis and feed on live tissue,” primarily affecting livestock.

NWS is “typically found in South America and the Caribbean,” according to the CDC.

However, cases in cattle and ranchers in Mexico have prompted the Trump administration in recent months to step up efforts to prevent it from reaching the U.S.

Despite efforts that included a project to breed and sterilize billions of flies for airdrop over Mexico and southern Texas, Nixon said the 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 CDC confirmed the case “through telediagnosis (i.e., expert review of submitted larvae images)” on Aug. 4, according to Nixon, who referred Axios to the Maryland Department of Health for details of the patient’s condition.