More Than 30 New World Screwworm Cases Confirmed in Texas and New Mexico

More than 30 New World screwworm cases have been confirmed in Texas and New Mexico, including two in dogs, Fortune reported. Veterinarians and humane societies issued warnings on Wednesday that pet owners must remain vigilant. The parasite reappeared in U.S.

Cattle in June after being largely eradicated from the country more than 50 years earlier. The screwworm is the larvae of the New World screwworm fly, which eats live flesh and fluids. The fly migrated north from Panama starting in 2024 and through Mexico in 2025.

The larvae can infest any mammal, including dogs, cats, wildlife and occasionally humans. They develop when a female fly lays eggs in open wounds or mucus. Newborn animals and those with open wounds or recent surgery are especially vulnerable, according to the American Veterinary Medical Association.

Even a tick bite can host an infestation, said Aaron Grady, executive director of the Houston Humane Society shelter. Affected areas include southern and southwestern Texas and southeastern New Mexico. Pet owners should examine animals regularly for wounds, cuts, bites, maggots or movement in a wound.

Signs of infestation include a foul smell, restlessness or an animal hyper-fixating on one area of the body, said Melissa Stansell, a veterinarian at Austin Pets Alive!. Flea and tick medications kill the larvae as they ingest blood and tissue, Stansell said. Veterinarians can treat infestations, and animals recover if owners seek care quickly.

Treatment may include antibiotics. The U.S. cattle industry is valued at $113 billion. The USDA invested $21 million to convert a site in southern Mexico from breeding fruit flies to breeding screwworm flies.

The agency also plans to spend $750 million on a new screwworm fly factory in Texas scheduled to open next year.