New World screwworm: Third US state reports case in dog as parasitic fly that eats animals alive spreads

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A dog in Arizona has been infested with New World screwworm, a parasitic fly that eats warm-blooded animals alive, the US Department of Agriculture said on Wednesday.
The first detection in Arizona was in Cochise County, which borders Mexico, according to the USDA. It widens the outbreak to a third US state.
The Arizona Department of Agriculture said the dog had a wound on its back that was infested with maggots, consistent with screwworm. It said scientific testing verified the infestation.
The dog was receiving veterinary care, the department added.
“We have been preparing for this possibility for a long while and are acting swiftly,” State Veterinarian Dr. Ryan Wolker said in a statement.
The Arizona case marks the latest sign that screwworm, eradicated from the US decades ago, may be regaining a foothold despite federal efforts to contain it, complicating the USDA’s attempts to reopen livestock trade with Mexico and ease record beef prices ahead of the midterm elections.
The USDA said it was restricting animal movement in a 20-km (12-mile) zone around the case. It said it was also increasing surveillance of live animals and releasing sterile flies that combat screwworm in response to the infestation.
The agency halted livestock imports from Mexico last year to try to keep out screwworm, which advanced north through Mexico and Latin America. It detected screwworm in a calf in Texas in June. It then confirmed additional cases in Texas and New Mexico.
As of Wednesday, the agency had reported 71 screwworm cases since June, and 18 were active, according to its website. There were only two active cases last month, and infestations have multiplied since then.
The import halt helped tighten US cattle supplies and push beef prices to record highs for American consumers. That has raised concerns about affordability ahead of the midterm elections.
The USDA began to resume livestock imports from Mexico in August, and has restarted trade at three ports of entry in Arizona and New Mexico.
The agency has said it next plans to resume imports from Mexico in Nogales, Arizona, on 30 November, if conditions for safe trade are in place in place.
Last week, the USDA confirmed the first case of screwworm in US wildlife in an elk in Texas.
