screwworm

New World screwworm is a livestock pest that can be a parasite of any warm-blooded animal, laying its eggs in even the tiniest of open wounds or cuts, including the bellybuttons of newborn animals, and in mucous membranes anywhere in the body.

Unlike other maggot-like infestations, "the screwworm eats live tissues, so it can cause significant tissue destruction and it can cause significant morbidity and even mortality," Isaac Bogoch, a general internist and professor of medicine at the University of Toronto who specializes in tropical infectious diseases, told Salon in a phone interview.

After digging deep lesions with their powerful maggot jaws, anchoring themselves inside them with their external spikes, screwworm larvae feed on the living flesh, working their way to deeper tissues like the muscles.

There isn't a medicine to treat screwworm.

Screwworm was once horribly endemic in the United States.