The first human screwworm case in the U.S. has been traced to a person in Maryland who traveled from Guatemala.

The person, who received treatment in Maryland, is the first new confirmed case this year in the U.S. of New World screwworm, a parasite that eats cattle and other warm-blooded animals alive, as an outbreak escalates and moves northward from Central America and southern Mexico.

A rare case of travel-related New World screwworm was identified in Maryland in a patient who traveled from El Salvador, a spokesman from the US Department of Health and Human Services said.