Key takeaways:

New World screwworm flies lay eggs in mammals’ wounds, causing an infestation of flesh-eating larvae.

The fly-borne scourge has inched closer to the U.S. southern border in recent years.

Perspective from Heather D.S. Walden, PhD

The first human case of New World screwworm infestation in the United States has been confirmed in a Maryland resident who returned from travel in Central America, according to health officials.

New World screwworms are parasitic flies that lay eggs in the open wounds of mammals — most often livestock, but also people, according to the CDC. The flies’ larvae, Cochliomyia hominivorax , infest and feed on the tissue.

Larvae from the New World screwworm fly can infest the tissue of mammals, including people. Image : Adobe Stock

The CDC

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