The United States Department of Agriculture (USDA) has confirmed a case of New World screwworm in a dog in Arizona, marking the third US state to report an infestation. The case was identified in Cochise County, near the Mexican border, according to the agency.
The dog had a wound on its back infested with maggots, and laboratory testing confirmed the screwworm infestation, the Arizona Department of Agriculture said. The animal is receiving veterinary care. State officials said they had prepared for the possibility of such a case and were responding swiftly.
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In response, the USDA has restricted animal movement within a 20-kilometre zone around the affected area, increased surveillance of live animals and released sterile flies to help control the parasite. The agency has also been monitoring cases in Texas and New Mexico after detecting the parasite in a calf in Texas in June.
“We have been preparing for this possibility for a long while and are โ acting swiftly,” State Veterinarian Dr. Ryan Wolker said in a statement.
As of October 28, the USDA had reported 71 screwworm cases since June, with 18 still active. The parasite, which was eradicated from the US decades ago, has been spreading north through Mexico and Latin America, raising concerns about livestock health and trade.
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The outbreak has complicated efforts to resume livestock imports from Mexico, which were halted to limit the parasiteโs spread. The USDA resumed imports through three ports in Arizona and New Mexico in August and plans to reopen trade at Nogales, Arizona, on November 30, provided conditions allow safe movement.









