A flesh-eating parasite known as the New World screwworm has been detected in a person in Maryland who had traveled to Central America. Screwworms are parasitic flies that lay eggs in warm-blooded animals. Once the eggs hatch, the larvae then burrow through living flesh using their sharp mouths, eventually killing their host. So far, no cases in animals have been confirmed, but the USDA has estimated a potential screwworm outbreak could cost Texas, the country's biggest cattle-producing state, a