Arizona confirms first New World screwworm case in a dog

UNITED STATES – Arizona has confirmed its first case of New World screwworm (NWS) in a canine in Cochise County, raising concerns about the spread of the livestock pest and the risk to other domestic and farm animals.

The Arizona Department of Agriculture (AZDA) announced the detection on 28 October 2026, after a local veterinarian examined the dog on the evening of 26 October. 

The animal had a wound on its back heavily infested with maggots consistent with NWS characteristics. Scientific testing, conducted in coordination with federal partners, confirmed the species.

The affected dog is receiving veterinary care. AZDA is working with the attending veterinarian and the owner to gather information for an epidemiological investigation and determine any necessary local response measures.

State Veterinarian Dr Ryan Wolker said the department had been preparing for a possible detection through outreach, surveillance and coordination with animal health partners.

The US Department of Agriculture (USDA) will establish an infested zone, increase animal surveillance and conduct outreach with local stakeholders. 

AZDA is also coordinating with federal authorities, neighbouring states and Mexican counterparts. The department has called for the release of sterile flies in the area to help suppress the pest population and prevent it from becoming established.

New detections raise concerns over animal health

The Arizona case follows the first confirmed detection of NWS in wildlife in the United States, reported on 21 October in an elk harvested on a game ranch in Pecos County, Texas. 

Authorities later said they would revise the boundaries of an existing infested zone and expand wildlife surveillance.

NWS has also reported cases in livestock and domestic animals in Texas and New Mexico.

The pest is the larval stage of a fly that lays eggs in open wounds or body openings of warm-blooded animals. The larvae feed on living tissue and can cause severe injury or death if infestations go untreated.

Over the past year, AZDA has worked with livestock owners, pet owners, Tribal partners, veterinarians and industry stakeholders to raise awareness of the pest. 

In collaboration with the University of Arizona’s Arizona Livestock Incident Response Team, the department has conducted more than 60 exercises, workshops and training events.

AZDA urges livestock and pet owners to inspect animals regularly, watch for wounds, and report suspected NWS infestations immediately.

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