U.S. confirms first New World screwworm cases in dog and goat

The U.S. Department of Agriculture confirmed the first case of the New World screwworm parasite in a dog in June and a second case in a goat in Texas. The dog was reported by a veterinarian in Texas, though officials said the animal resided in New Mexico. Officials inspected additional animals at the dog's home and are working to identify its travel history.

Parasite details The New World screwworm is a species of parasitic fly that has been moving northward through South and Central America since 2023, according to the Centers for Disease Control and Prevention. The fly completes its life cycle by laying 200 to 300 eggs in open wounds or body openings of warm-blooded animals.

Once hatched, the maggots consume tissue and create painful, foul-smelling wounds. The parasite is not contagious between animals and is not zoonotic.

Prevention guidance The CDC recommends keeping open wounds clean and covered, sleeping indoors with closed or screened windows, and checking animals regularly for wounds. Owners should contact a veterinarian with concerns and avoid attempting to remove maggots themselves.

Texas A&M Veterinary Medicine and Biomedical Sciences suggests keeping pets on routine parasite-preventative medicines. The USDA is working with the Texas Animal Health Commission to establish surveillance and testing. “This situation is evolving, and we expect new information to emerge as our investigation continues.

USDA is committed to sharing what we learn quickly, accurately, and transparently so animal owners and local communities have the information they need to stay vigilant,” said Dudley Hoskins, Under Secretary for Marketing and Regulatory Programs.