USDA confirms first screwworm case in Arizona, in a dog
The dog lives in Cochise County, on the Sonora border. USDA wants pets checked daily, and the CDC lists the warning signs in people.
A dog in Cochise County, in southern Arizona, is the first animal in the state found with the New World screwworm, the U.S. Department of Agriculture's Animal and Plant Health Inspection Service confirmed on Oct. 28. The county borders the Mexican state of Sonora.
The diagnosis was confirmed at the agency's national veterinary laboratory in Ames, Iowa. Arizona becomes the third state with animal cases in this outbreak, after Texas and New Mexico.
USDA and the Arizona Department of Agriculture set up an infested zone of 20 kilometers (12 miles) around the case. Inside it, animal movement is controlled, surveillance and trapping are stepped up, sterile flies are being released, and officials are reaching out to producers, veterinarians and communities.
What USDA and the CDC recommend
Owners of pets or livestock should check their animals every day, USDA says. The signs it lists are wounds that grow or drain, maggots or egg masses inside a wound, discomfort or irritability, and sores around the ears, nose, genitals and navel. If an owner suspects an infestation, the agency asks for an immediate call to a veterinarian, the state animal health authority or USDA itself.
The parasite can also infest people, though less often. The announcement reports no human cases in Arizona.
The CDC's guidance was first posted in August 2025 and last reviewed July 8, 2026. It describes the signs in a person as feeling or seeing maggots move in a wound or in the ears, nose, eyes or mouth, plus painful sores that worsen within days, a foul smell and bleeding. People at higher risk, it says, include those who live in or travel to areas with infested animals, anyone with an open wound, however small, and people who spend long periods around livestock.
If maggots appear, the CDC says to contact a health care provider right away and mention any recent travel to an area with cases. It warns against removing the maggots without help or throwing them out alive. For prevention, it recommends keeping wounds clean and covered and using an EPA-registered insect repellent.
The current count of detections is on screwworm.gov, a public dashboard that refreshes every afternoon.
USDA's advice is aimed at animal owners in areas with cases, and the CDC's at people who live in or travel to those areas and people with open wounds. It is not general advice for the whole population and does not replace a visit to a veterinarian or a doctor.
