Maryland Traveler Diagnosed With Rare Flesh-Eating Parasite

Maryland Traveler Diagnosed With Rare Flesh-Eating Parasite After Trip to El Salvador

hominivorax, the New World screw-worm fly, or screw-worm for short, is a species of parasitic fly that is well known for the way in which its larvae (maggots) eat the living tissue. — Source: Lidya Elfa Sari / Getty

A Maryland resident has been diagnosed with New World screwworm following travel to El Salvador, marking the first reported U.S. case linked to a country with an active outbreak, federal health officials confirmed.

The Centers for Disease Control and Prevention (CDC) verified the infection on Aug. 4. State health officials said the patient has since recovered, and no spread to other people or animals has been detected.

New World screwworm, a parasitic fly, lays its eggs in open wounds and body cavities. The larvae feed on living tissue, making the parasite a major threat to livestock in parts of South America and the Caribbean. Human infections are rare.

The pest, once a persistent problem for cattle ranchers in Florida and Texas, was eradicated from the U.S. by the 1970s through a sterile-fly release program. But recent outbreaks in Central America and Mexico have raised concerns about its northward spread.

“This may not be the first American ever diagnosed with it, but it’s certainly the first in quite some time,” said Max Scott, a North Carolina State University researcher who studies the parasite.

What to Know About New World Screwworm

The fly’s Latin name translates to “man eater.”
Females deposit eggs in open wounds or in the nose, eyes, or mouth. The maggots, which grow up to two-thirds of an inch, burrow into tissue in a corkscrew-like motion.
Infections in people do not spread person-to-person, and overall risk in the U.S. remains very low, officials say.
Symptoms include painful, slow-healing wounds, foul odors from infected areas, and visible larvae.
Treatment requires removal of the larvae, sometimes surgically. The CDC cautions against attempting removal without medical help.

To reduce risk, travelers in affected regions are advised to protect wounds, limit exposure to livestock, and avoid sleeping outdoors.

U.S. officials are expanding efforts to prevent the parasite’s reestablishment, including new genetic techniques to control fly populations. If it does return, experts warn the Texas-Mexico border would likely be the first entry point.