A rare human case of a flesh-eating parasite known as New World screwworm has been confirmed in a Maryland resident as the Trump administration is trying to prevent the resurgence of an insect largely eradicated from livestock decades ago.

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

The parasite — the larvae of the new world screwworm fly — can devastate cattle herds and is rife in parts of Central America.