The first case of a New World Screwworm infestation in a human was confirmed in the U.S., according to the Department of Health and Human Services.
Travel-associated New World Screwworm was detected in a patient who returned to the U.S. from El Salvador, and was confirmed by the Centers for Disease Control and Prevention on Aug. 4, HHS spokesperson Andrew Nixon said in a statement to CBS News on Monday.
The CDC investigated the case in coordination with Maryland’s health department.
“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,” Nixon said, adding that the risk to U.S. public health is currently “very low.”
What is New World Screwworm myiasis?
New World Screwworm myiasis is a parasitic infestation of fly larvae, or maggots, caused by New World Screwworm (NWS) parasitic flies, which feed on live tissue, the CDC says.
“When NWS fly larvae (maggots) burrow into the flesh of a living animal, they cause serious, often deadly damage to the animal,” the USDA says. “NWS can infest livestock, pets, wildlife, occasionally birds, and in rare cases, people.”
The Texas Parks and Wildlife Department says NWS flies lay eggs in “open wounds or orifices of live tissue such as nostrils, eyes or mouth” — an infestation and painful condition, known as New World screwworm myiasis.
“These eggs hatch into dangerous parasitic larvae, and the maggots burrow or screw into flesh with sharp mouth hooks,” the parks department says. “Wounds can become larger, and an infestation can often cause serious, deadly damage or death to the infected animal.”
It is usually found in South America and the Caribbean. Those at higher risk of suffering from the condition include people living in rural areas in places where NWS is endemic, and where livestock are raised, as well as people with open sores or wounds, and vulnerable populations, the CDC says.
There is no medication to treat it, according to the agency.
Late last year, Texas officials posted an advisory for outdoor enthusiasts in South Texas after New World Screwworm was found in a cow in the southern Mexican state of Chiapas. The Texas Parks and Wildlife Department said New World Screwworm had been making its way further north through the Americas.
“As a protective measure, animal health officials ask those along the southern Texas border to monitor wildlife, livestock and pets for clinical signs of NWS and immediately report potential cases,” the department said at the time.
In June, the U.S. government released a policy initiative aimed at stopping the spread of New World screwworms in live cattle and other animal imports, including a plan to build an insect dispersal facility in Texas.
