Screwworm found in Arizona dog, third US state with infestations

what happened

The US Department of Agriculture has confirmed a New World screwworm infestation in a dog in Arizona, extending the parasite's footprint in the country to a third state, Reuters reports. The first Arizona detection was in Cochise County, which sits on the Mexican border.

The dog had an open wound on its back containing maggots consistent with screwworm, and laboratory testing verified the infestation, the Arizona Department of Agriculture said. State Veterinarian Ryan Wolker said the state had prepared for such a case for a long time and was responding quickly.

The US halted livestock imports from Mexico last year to block the pest, but a calf in Texas was found infested in June, followed by more cases in Texas and New Mexico. The USDA has counted 71 cases since June, 18 of them active, up from only two active cases a month earlier. Trade has resumed at three ports of entry in Arizona and New Mexico since August, and the agency plans to reopen Mexican livestock imports at Nogales on November 30, provided trade can be conducted safely.

why it matters

The import ban has already tightened US cattle supplies and helped push beef prices to record highs for consumers. Further spread of the parasite could keep livestock supply constrained and delay any easing tied to reopening Mexican imports.

market impact

Live cattle and beef: continued import curbs keep US cattle supply tight, supporting prices

• ▲Live cattle futures pressure up — import curbs from Mexico keep US cattle supply tight

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