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

Health officials confirm that a Maryland resident was diagnosed with New World screwworm earlier this month after traveling to El Salvador. It has been declared the first human case in the United States by the Centers for Diesease Control and Prevention.

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.