A flesh-burrowing parasite that can terrorize humans and animals alike has made its dreaded return to the United States. Late Wednesday afternoon, officials from the United States Department of Agriculture reported a case of New World screwworm detected in a 3-week-old calf in Texas. It’s the first known case of the parasite among U.S. livestock reported in decades, following a concerted eradication program. Officials say they are implementing containment measures to ensure the screwworm does not reestablish itself within the country as it has lately in many areas of the Americas. The ‘man-eater’ maggot returns The New World screwworm is actually a species of fly formally called Cochilomyia hominivorax. Its nickname comes from the fly’s larval form: a maggot shaped like a screw. Adult flies will lay eggs into the open wounds or mucous membranes (eyes, for instance) of their warm-blooded hosts, after which the maggots will use their screw-like bodies to burrow ever deeper into the flesh of their hosts.…