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Pima County horse contracts New World screwworm, first animal case in county
A domesticated horse near Tucson with no travel history tested positive for the flesh-eating parasite, marking Arizona's seventh animal case and prompting a virtual town hall Monday. Health officials say human risk remains low but urge wound care.
Pima County health officials confirmed Saturday that a domesticated horse near Tucson has tested positive for New World screwworm, the first animal case detected in the county. The Arizona Department of Agriculture said the horse had no known history of travel, raising concerns that the parasite may be spreading locally.
The case brings Arizona's total to seven reported animal infections. No human cases have been reported in the United States.
"The identification of the first New World Screwworm animal case in Pima County is concerning, but the risk to humans remains low," said Dr. Theresa Cullen, director of the Pima County Health Department. "We are coordinating with our state health and agricultural partners and will continue to keep residents informed as more information becomes available."
New World screwworm is a parasitic fly whose larvae feed on living tissue of warm-blooded animals, including livestock, pets, and occasionally humans. Infestations can be fatal if untreated. The pest was once eradicated from the U.S. through sterile insect releases but has reemerged in recent years.
Cullen advised residents to seek prompt medical attention for open, draining, or non-healing wounds, especially if they notice signs of insect infestation such as visible maggots. "We encourage residents to seek medical care for wounds that are not healing properly and to follow guidance from public health and animal health officials," she said.
In response to the detection, the Pima Animal Care Center is pre-treating all dogs ahead of its Fall Festival adoption event on Sunday. Officials did not specify what treatment is being used but said it is a precautionary measure.
State and county officials will host a virtual town hall on Monday from 5:30 p.m. to 8:30 p.m. to answer questions about the cases and the response. The meeting can be accessed at https://arizona.zoom.us/j/89847196269.
The latest information on Arizona New World screwworm cases is available at the Arizona Department of Agriculture's website: https://agriculture.az.gov/divisions/animal-services/state-veterinarians-office/new-world-screwworm.
The detection near Tucson underscores the importance of monitoring for invasive species that can threaten both animal and public health. Residents are urged to report suspected cases to agricultural officials and to practice good wound care.