The person, who received treatment in Maryland, is the first confirmed case in the U.S. of New World screwworm, a parasite that eats cattle and other warm-blooded animals alive, since an outbreak began to escalate and move northward from Central America and southern Mexico late last year.

Screwworms can be devastating in cattle and wildlife, and rarely infest humans, though an infestation in either an animal or a person can be fatal.