US Official Shuts Down Mexico/Arizona Border to Stop Deadly Disease

There's a serious situation brewing just south of Arizona's border with Mexico. Mexico's agricultural agency, the National Service of Agro-Alimentary Health, Safety, and Quality (SENASICA), reported that a nasty invader could be headed across Arizona's southern border.

The New World Screwworm, or Cochliomyia, is a genus in the family Calliphoridae, known as blowflies. The New World Screwworm is a nasty little fly whose larvae feed on the living flesh of animals. It's been detected in northern Mexico, and it's currently inching dangerously close to the U.S. border.

What Is the New World Screwworm?

This pest isn’t just a nuisance; it can kill livestock and pets. The screwworm burrows into wounds and turns minor injuries into festering nightmares. Livestock, pets, wildlife, and even people are at risk.

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That’s why, as of July 9, the USDA slammed the doors on livestock coming through Arizona's southern ports of entry, with the goal of stopping infected animals from crossing into our state and the rest of the United States.

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How Screwworms Affect Animals and Humans

The screwworm’s northward march through Veracruz and Oaxaca triggered this USDA emergency response. The threat was identified earlier in the year, triggering border closures in May.

Screwworm Infestation: What to Watch For

According to the Equine Disease Communication Center (EDCC), watch for animals shaking their heads, acting irritated, or showing signs of decay around wounds. If you spot maggots in a wound, don’t wait; call your vet immediately.

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How to Report and Treat Infections

Treatment involves removing larvae, cleaning the wound, and isolating the animal. Veterinarians have medications that may aid in treatment, especially if the infection is caught early.

Samples of larvae should be sent by your vet to your state’s diagnostic lab for confirmation. Horses, livestock, pets, and even humans are vulnerable. If you’ve traveled with your horse, dog, or cat through affected areas, get them checked.

What Arizona Livestock Owners Should Do Now

If you're involved with 4-H, FFA, or other events where livestock is traveling for state or county fairs and competitions, keep a close eye out for signs of infection. Prevention is key: keep wounds clean, use fly repellents, and report anything suspicious.

USDA’s Emergency Response Plan

The USDA is fighting back with sterile fly releases and a new dispersal facility in South Texas. But here in Arizona, vigilance is our best defense to keep our herds and our pets safe. If you see anything suspicious, contact a veterinarian immediately.

Sources: USDA | Equine Disease Communication Center (EDCC) | NMSU Publications