When a PRT reporter was assigned a story early last month on the possible spread of New World screwworm to Arizona, the overall message was to stay vigilant with your pets and livestock, but don’t let it stress you out.
While cases of the parasitic blowfly had been reported in New Mexico, Texas and Florida, Arizona was, at the time, screwworm-free.
That all changed last week.
On Wednesday, Oct. 28, the Arizona Department of Agriculture announced that the state had its first case of screwworm, found in a canine in neighboring Cochise County.
The dog had a wound on its back “heavily infested with maggots consistent with NWS characteristics,” the news release said. Follow-up testing confirmed it. A second case has since been detected in a horse, also in Cochise County.
State Veterinarian Dr. Ryan Wolker’s message echoed what Patagonia resident and retired federal veterinarian, Steve Finch, told our reporter earlier in the month: That plans for the arrival of screwworm had been in place for some time.
“Because of the extensive outreach, coordination, and surveillance already in place, Arizona producers, veterinarians, and pet owners know what to look for and how to report suspected cases,” Wolker said. “That preparation is allowing us to move quickly to protect animal health in the state.”
According to the U.S. Centers for Disease Control and Prevention, the New World screwworm (NWS) is a fly that lays its eggs in an open wound, body openings such as eyes, ears, nose or mouth, or possibly the umbilicus of a newborn animal.
The eggs hatch into larvae that feed on living tissue.
The larva is shaped and acts like a screw that you get at the local hardware store. It screws into the living tissue, breaking down that tissue and causing a condition called myiasis. Without treatment, the infestations can be fatal.
Primarily a species of the tropics and warm climates, these insects have not been a big factor in most of the US livestock industry. However, with factors such as climate change, the increased movement of animals, and gaps in veterinary surveillance, the affected animals can spread this scourge. Birds, pets and even humans can all be infected.
Dogs and cats are vulnerable because minor injuries can attract the flies. Pet owners are encouraged to check their animals for wounds and monitor for any foul odors or tissue damage. The affected dog in Cochise County is under veterinary care and the Arizona Department of Agriculture is working with the vet and the owner to gather more information, the news release said.
“Federal response actions from (United States Department of Agriculture) will include establishing an Infested Zone, increasing animal surveillance, and conducting outreach to local partners,” it continued.
The news release said the AZDA is advocating for the release of sterile flies in the area to help suppress the fly population.
The practice goes back to the 1960s, when a technique was developed to sterilize male fly larva as pupas. The sterile flies were then distributed by air over the affected areas to mate with their female counterparts.
The technique proved effective in eradicating the screwworm spread. It was continued with the cooperation of Mexico and countries throughout Central America.
Plans for a sterile fly dispersal facility in Douglas are in the works, the news release said.
The AZDA said anyone with pets or livestock should remain vigilant, especially if any unusual wounds are discovered on their animals. They are asked to call the AZDA offices at 1-602-542-4293 or email diseasereporting@azda.gov.
Hunters and outdoor enthusiasts are asked to call Arizona Game and Fish at 1-623-236-7201 if they see the same type of wounds in local wildlife.
