The first U.S. human case of infection from the New World screwworm, a flesh-eating parasite, was recently detected in Maryland.
The New World screwworm is a fly larva that infests the living tissue of warm-blooded animals, including humans, causing a painful condition known as myiasis, according to a June report from the USDA Animal and Plant Health Inspection Service (APHIS),
Myiasis is a parasitic infestation of fly larvae (maggots) in human tissue, according to the U.S. Centers for Disease Control.
According to information from the Maryland Department of Health, a resident experiencing myiasis from a case of New World screwworm infection had recently returned to Maryland from a country experiencing an NWS outbreak.
This is the first human case of the screwworm infection in the U.S., FOX 5 DC reported, citing the CDC.
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New World screwworm
(USDA via APHIS / FOX Weather)
Reports of the screwworm in the U.S. aren’t common, the CDC reported. The USDA reports the screwworm was eradicated from the US in 1966 and a small outbreak in 2017 in the Florida Keys was eliminated.
And cases in humans are rare, but people who have open wounds, sleep outside or work around livestock are at a greater risk of being infected by the parasite.
But currently, the risk to public and animal health in Maryland from this introduction is very low, the Maryland Department of Health said.
The MDDOH said an investigation conducted by the CDC, U.S. Department of Agriculture and several other state and national agencies confirmed there is no indication of transmission to any other people or animals, and the infected resident has recovered from the infection.
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This image shows screwworm larvae.
(CDC / FOX Weather)
According to the APHIS, the NWS is currently known to exist in parts of every country in South America except Chile, as well as in parts of the Caribbean.
The APHIS said Panama reported a dramatic increase in the number of NWS cases in 2023, and since then has spread northward through Central America. And in November 2024, the screwworm reached the southern state of Mexico.
