The flies are most often found in South America and parts of the Caribbean, but in the last few years have also moved into Central America and Mexico.

New World screwworm (NWS) is a parasitic fly that can feed on the tissues of warm-blooded animals and lay their eggs in open wounds or body openings, such as the nose, eyes, ears, and mouth.

NWS was eradicated in the United States about 60 years ago, but the U.S.

Department of Agriculture (USDA) recently confirmed a case in a calf in Texas.

Since then, a total of seven cases have been documented, including in a dog in New Mexico.

Isabelle Louge , clinician with Tufts Veterinary Field Service (TVFS) and assistant clinical professor in the Department of Large Animal Clinical Sciences at Cummings School of Veterinary Medicine at Tufts University, answers questions for animal owners about New World screwworm.

What are t…