Maryland reports first US screwworm case as outbreak nears border

A Maryland resident treated for the New World screwworm, a rare flesh-eating parasite, has been identified after returning from Central America, marking the first confirmed human case in the United States since the outbreak began moving north late last year. Officials say the health risk to the public remains low, but the incident highlights the potential economic exposure to the U.S. cattle industry as authorities accelerate containment and bolster production of sterile flies to stop the pest at the border and beyond.

Details about the patient’s travel history have not been publicly disclosed by health authorities due to privacy rules, though multiple briefings indicated the person had recently traveled from Central America. The case was confirmed by federal health officials through telediagnosis, a remote diagnostic method, and the patient has received treatment. Maryland state officials say prevention measures were implemented, but no further clinical details are being released.

Screwworms are parasitic flies whose larvae feed on living tissue, most often affecting cattle, wildlife and other warm-blooded animals, and only rarely humans. The life cycle is rapid: after eggs...