USDA Confirms New World Screwworm Cases in Texas and New Mexico

The United States Department of Agriculture (USDA) has confirmed cases of New World screwworm affecting calves in Texas and a dog in New Mexico, marking the first detections of this parasitic fly in the U.S. in decades. The New World screwworm is known for its larvae, which invade living tissue, resulting in painful and rapidly worsening wounds in pets, livestock, wildlife, and, in rare instances, humans.

Previously eradicated from the United States in 1966, the resurgence of this species is a significant concern for animal health. Currently, the risk to most pets is considered low, but awareness and early detection are critical. Pet owners should consult a veterinarian if their dog develops a wound that does not heal properly or shows signs of worsening, such as foul odor, drainage, or visible maggots.

Veterinarians recommend year-round parasite prevention to maintain pet health. Options like permethrins, found in products such as K9 Advantix, help repel flies, while isoxazolines like NexGard and Credelio can kill larvae. Pet owners are encouraged to discuss the best parasite prevention strategies with their veterinarian.

All confirmed cases of New World screwworm should be reported to the USDA. Further information regarding this health threat can be found through the Cornell Animal Health Diagnostic Center.