Facts
- The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) confirmed a case of New World screwworm in a dog in Cochise County, Arizona, on Wednesday, October 28, 2026. APHIS called it the first detection of the parasite in Arizona.
- Samples were tested and confirmed at the APHIS National Veterinary Services Laboratories in Ames, Iowa.
- KJZZ reported that the dog was found on a ranch, is being treated and is expected to survive, and has no known history of movement to other states or counties.
- APHIS said it is working with the Arizona Department of Agriculture on a joint response: a 20-kilometer infested zone around the detection with animal movement controls, more live-animal surveillance and trapping, sterile fly releases, and outreach to local producers, veterinarians and communities.
- KJZZ reported that about one million sterile flies have been released in the Cochise County area. Officials are evaluating other livestock on the ranch.
- The larvae of the fly feed on living tissue and are laid in wounds of warm-blooded animals. Officials told KJZZ the parasite does not threaten the existing food supply because it infects only living tissue.
- Before this detection, a horse with an infested wound was found in Grant County, New Mexico, about 50 miles from the Arizona border. USDA and New Mexico officials announced that case on September 17. As of September 28, USDA data showed 51 confirmed U.S. animal detections since June, when the first U.S. case in decades was found in a calf in Texas, AZFamily reported.
- APHIS did not state a current national total in its announcement and points readers to its dashboard at screwworm.gov, updated daily at 6 p.m. ET.
Quotes
Paul Brierley, director of the Arizona Department of Agriculture, said: “We’ve not had any cases in Arizona until today’s confirmed case.”
Ryan Wolker, Arizona’s state veterinarian, said of the ranch: “There’s other livestock on the ranch, which we will be evaluating.”
Source Read the USDA APHIS announcement here.
Image Screwworm – Cochliomyia hominivorax, Big Pine Key, Florida by Judy Gallagher, licensed under CC BY 2.0.
