A domestic dog in Cochise County, Arizona, has tested positive for New World screwworm, marking the first time this parasite has been detected in the state. The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) confirmed the case on October 28, 2026, after samples were analyzed at the National Veterinary Services Laboratories in Ames, Iowa.
New World screwworm larvae feed on living tissue of livestock, pets, wildlife, and, less commonly, people, causing severe wounds and animal suffering. For Arizona’s agricultural sector, an infestation can cause significant economic impacts if not detected and treated quickly.
Containment in Cochise County
The response is immediate. APHIS and the Arizona Department of Agriculture have activated the APHIS NWS Response Playbook. The center of the effort is a 20-kilometer infested zone established around the latest detection.
Inside this zone, the government is implementing animal movement controls. Field teams are increasing live animal surveillance and trapping. To combat the population, officials are releasing sterile flies.
In the livestock industry, a screwworm infestation can cause severe wounds and animal suffering.
What Pet and Livestock Owners Need to Watch For
Owners should inspect their animals daily for any wounds that seem to be draining or enlarging.
- Visible Parasites: The presence of maggots or egg masses within wounds.
- Behavioral Shifts: Signs of discomfort or irritability.
- Strategic Lesions: Lesions around body openings, specifically the ears, nose, genital area, and the umbilicus.
If any of these signs appear, the directive is clear: contact a veterinarian, state animal health official, or USDA immediately. The USDA has centralized reporting and tracking via the public dashboard at screwworm.gov, which updates daily at 6:00 p.m. ET to provide a list of confirmed detections.
