Arizona Dog is State’s First Animal Infected With Screwworm as Cases Spread
WHO:
Newsweek - An Arizona dog was identified as the state’s first animal infected with New World screwworm in decades.
ABC News - Arizona officials confirmed the state’s first animal case of New World screwworm (NWS).
ABC News - The infected canine, its owner and attending veterinarian were involved in the state’s response.
ABC News - Dr. Ryan Wolker, the state veterinarian, said Arizona had prepared for the possibility of a case.
ABC News - The U.S. Department of Agriculture (USDA), Arizona Department of Agriculture (AZDA), Centers for Disease Control and Prevention (CDC), local partners, producers, veterinarians and pet owners were involved in or addressed by the response.
ABC News - A Department of Health and Human Services spokesperson said a Maryland resident who had recently returned from El Salvador was infected last year; no human cases had been reported this year.
WHAT:
Newsweek - New World screwworm was detected in an Arizona dog, marking the state’s first case in decades.
ABC News - Arizona became the third U.S. state to report an animal NWS case; Texas and New Mexico had previously reported animal infections, according to USDA data.
ABC News - The dog’s wound was heavily infested with maggots; testing confirmed they were NWS.
ABC News - The canine was under veterinary care, and AZDA was gathering additional information with the veterinarian and owner.
ABC News - Officials said the public-health risk was low.
ABC News - NWS larvae feed on living tissue and can cause myiasis; the flies can infest livestock, pets, wildlife and, rarely, humans.
ABC News - The parasite’s larvae can cause extensive tissue damage and may lead to death.
ABC News - AZDA called for sterile flies to be released in the area to suppress the fly population and “prevent the pest from becoming established.”
WHERE:
ABC News - The case was identified in a canine in Cochise County, southeastern Arizona, near the Mexico border.
ABC News - USDA was establishing an infested zone and increasing animal surveillance in response.
WHY:
ABC News - Officials said sterile flies were sought to suppress the population and prevent NWS from becoming established.
ABC News - The CDC said travelers to outbreak areas, people spending time among livestock, people sleeping outdoors and people with open wounds face greater risk.
HOW:
ABC News - A local veterinarian examined the dog and found a wound on its back “heavily infested with maggots”; testing confirmed the species.
ABC News - Dr. Ryan Wolker said outreach, coordination and surveillance were already in place to help producers, veterinarians and pet owners recognize and report suspected cases.
ABC News - USDA’s response included establishing an infested zone, increasing animal surveillance and conducting outreach to local partners.
ABC News - NWS had been eradicated in the United States for decades by sterilizing male flies and releasing them to mate with females until the population died out; cases among livestock had migrated north through the southern border over the past year.
ABC News - The species is Cochliomyia hominivorax; its larvae use sharp mouth hooks to screw into animal tissue.
(UPDATED October 29, 2026 22:07 UTC)
Arizona has confirmed its first New World screwworm case in decades, after testing identified the parasite in maggots infesting a dog’s wound in Cochise County near the Mexico border. The dog is receiving veterinary care, and officials say the public-health risk is low; Arizona is the third state to report an animal case, after Texas and New Mexico. State and federal agencies are increasing surveillance, establishing an infested zone and seeking the release of sterile flies to suppress the population and prevent the pest from becoming established.