Arizona Reports First New World Screwworm Case in Dog, Expanding Outbreak to Third U.S. State
A dog in Arizona has contracted an infestation of the New World screwworm, marking the first confirmed case of the parasitic fly in the state and widening a growing regional outbreak to a third U.S. jurisdiction. The U.S. Department of Agriculture announced the detection on Wednesday, locating the case in Cochise County along the Mexican border.
According to the Arizona Department of Agriculture, scientific testing verified the infestation after the animal was found with a maggot-ridden wound on its back. The affected dog is currently undergoing veterinary treatment. State Veterinarian Dr. Ryan Wolker noted in a public statement that agricultural authorities had anticipated the potential spread and were responding with immediate containment measures.
Federal and state agricultural officials have moved to establish a 20-kilometer, or 12-mile, restriction zone around the site of the infection to limit animal movement. Response protocols also include stepped-up surveillance of live animals and the deployment of sterile flies designed to suppress the pest population.
The parasite, which consumes warm-blooded animals in its larval stage, had been eradicated from the United States decades ago. However, recent northward migration through Mexico and Latin America has allowed the fly to reestablish a presence, threatening domestic livestock and complicating federal trade policies.
As of Wednesday, federal tracking data showed a total of 71 screwworm cases reported since June, with 18 remaining active. The current figures reflect a sharp increase from the previous month, when only two active cases were recorded. The outbreak previously expanded into Texas, where officials confirmed an infection in a calf in June followed by additional cases, as well as New Mexico. Last week, authorities also confirmed the first wildlife infection in a Texas elk.
The resurgence of the parasite has had broader economic and political repercussions. Federal authorities previously halted livestock imports from Mexico to prevent the pest from crossing the border, a restriction that tightened domestic cattle supplies and drove American beef prices to record highs. Those supply pressures have raised consumer affordability concerns ahead of the midterm elections.
The USDA began allowing limited livestock imports to resume in August across three ports of entry in Arizona and New Mexico. Current plans indicate that trade restrictions could loosen further on November 30, with a scheduled resumption of imports through Nogales, Arizona, provided that safe trade conditions remain met.
