New US screwworm case: A human case of the flesh-eating New World screwworm parasite has been confirmed in Maryland in a person who recently traveled to the United States from Guatemala, according to Reuters. The patient, who received treatment in Maryland, marks the first confirmed human case in the US since the outbreak began spreading northward from Central America and southern Mexico late last year.
CDC Confirms Human Screwworm Case in Maryland: Report
Beth Thompson, South Dakota’s state veterinarian, told Reuters on Sunday that she had been informed of the case within the past week by someone with direct knowledge of the Maryland situation.
*FIRST HUMAN CASE OF NEW WORLD SCREWWORM DETECTED IN US
Here we go again.
— Spencer Hakimian (@SpencerHakimian) August 24, 2025
Reuters quoted a source, saying they had seen emails sent by an executive of the industry group Beef Alliance on August 20. The emails were addressed to roughly two dozen individuals in the livestock and beef sectors, stating that the US Centers for Disease Control and Prevention (CDC) had confirmed a human screwworm case in Maryland.
Maryland Veterinarians Informed By CDC on Human Screwworm Case
State veterinarians reportedly learned of the case during a call with the CDC last week. A Maryland state government official also confirmed the occurrence to Reuters.
Thompson described challenges in obtaining information from the CDC. “
BREAKING: Case of flesh-eating screwworm parasite identified in person in 🇺🇸 Maryland, the United States, after traveling from Guatemala, according to Reuters report.
— The Spectator Index (@spectatorindex) August 24, 2025
We found out via other routes and then had to go to CDC to tell us what was going on,” she said. “They weren’t forthcoming at all. They turned it back over to the state to confirm anything that had happened or what had been found in this traveler.”
The confirmation comes just over a week after US Department of Agriculture (USDA) Secretary Brooke Rollins and other officials visited Texas to announce plans to build a sterile fly facility aimed at combating the pest.
What Are Screwworms?
Screwworms are parasitic flies whose females lay eggs in wounds on any warm-blooded animal. Once hatched, larvae burrow into living flesh using sharp mouthparts. If untreated, infestations can be fatal.
The maggots’ feeding pattern resembles a screw being driven into wood, which is how they earned the name “screwworm.” While rare in humans, infestations can devastate livestock and wildlife. Treatment is labor-intensive, requiring the removal of hundreds of larvae and thorough wound disinfection, but early intervention can save lives.
How Screwworms Threaten Livestock and the Beef Industry
Screwworm infestations are highly destructive to livestock. The parasite was eradicated in the US during the 1960s through a sterile fly program, but the recent northward spread from Central America has raised concerns about a potential outbreak.
The US cattle herd is currently at its smallest size in 70 years, while beef prices are at record highs. Experts warn that an uncontrolled outbreak could severely impact ranchers, the beef market, and food prices, potentially causing losses in the billions.
The USDA is ramping up measures to contain the threat. Secretary Rollins recently announced the construction of a sterile fly production facility in Texas, expected to take two to three years to become operational.
At present, the only active sterile fly facility is in Panama, producing 100 million sterile flies per week – far below the amount experts say is needed to contain the outbreak. Mexico has also begun constructing its own $51 million facility to combat screwworms.
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Zubair Amin is a Senior Journalist at NewsX with over seven years of experience in reporting and editorial work. He has written for leading national and international publications, including Foreign Policy Magazine, Al Jazeera, The Economic Times, The Indian Express, The Wire, Article 14, Mongabay, News9, among others. His primary focus is on international affairs, with a strong interest in US politics and policy. He also writes on West Asia, Indian polity, and constitutional issues. Zubair tweets at zubaiyr.amin
