Devastating flesh-eating screwworm was spotted within 31 miles of US Border, USDA says, and it can spell doom for America’s livestock industry

A devastating parasitic fly that eats warm-blooded animals alive has been found in a young sheep in Mexico within 31 miles of the U.S. border, the U.S. Department of Agriculture said, as reported by Reuters. This is another massive concern for the agricultural sector, as the New World Screwworm is capable of causing millions of dollars in economic damage to the U.S. economy. The detection, which occurred in a six-month-old sheep in Coahuila state, marks the closest the parasite has come to the U.S. during the most recent outbreak.

It’s easy to see why this is so terrifying for cattle producers. The U.S. cattle herd is currently at its lowest levels in 75 years, and beef prices have already hit record highs. If this fly makes its way into the U.S., experts warn it could cause prices to spike even further by keeping more calves out of the supply chain. For Texas alone, which is the biggest cattle-producing state in the country, a potential outbreak could result in $1.8 billion in economic damage.

The biology of the New World Screwworm is truly horrific. Female flies lay hundreds of eggs in wounds on any warm-blooded animal. Once those eggs hatch, the larvae use their sharp, hooked mouths to burrow through living flesh, feeding on the animal and enlarging the wound. If left untreated, the infestation eventually kills the host. A tiny scrape, a recent brand, or even a healing ear tag can quickly become a gaping, infested wound.

Treatment for this is incredibly low-tech and physically exhausting

Vets and ranchers must manually scrape each worm out of the infested animal before spraying the wounds with an insecticide. It’s a labor-intensive process that requires a massive amount of boots on the ground. As rancher Kip Dove, who remembers the last major outbreak in 1973, noted, the experience is haunting. He recalls the smell of rotting flesh and the sight of cattle kicking at their open wounds. “The smell is bad, and some of the wounds are horrific. You have humongous holes in these animals teeming with worms,” Dove said. “I don’t know if I could handle it if it happens now.”

The situation is complicated by a shortage of skilled ranch labor. Modern ranches simply don’t have enough cowboys to monitor and treat herds with the necessary intensity. Managing an outbreak requires checking every single head of cattle every single day, which is a punishing routine. Isaac Sulemana, a rancher and attorney in Sullivan City, Texas, mentioned that his ranch would need at least 10 cowboys to monitor pastures during an outbreak, but he only has two.

The U.S. government has been trying to stay ahead of the curve. Washington has blocked cattle imports from Mexico for over a year, and the USDA has invested millions of dollars into facilities that breed sterile flies. These sterile flies are the most powerful tool for quelling an outbreak, as they mate with wild females to produce infertile eggs. We have also seen Google entering the fray with their Debug project. Unfortunately, these facilities have not yet come online. There is also the issue of scale. The USDA estimated that 500 million flies need to be released weekly to push the fly back to the Darien Gap, but the current production capacity is nowhere near that figure.

As it stands, the hunting industry is also at high risk. Managers like Freddy Nieto at El Sauz Ranch in South Texas are worried because wildlife infested with screwworms are essentially impossible to treat. These animals often disappear into thick brush to die, making them a silent, spreading vector for the parasite. Dr. Thomas Lansford, the assistant state veterinarian at the Texas Animal Health Commission, summed up the current state of affairs well when he said, “It’s an overwhelming situation at this point.”

Ranchers are now doing what they can to prepare. Many are stockpiling insecticides and making contingency plans, though the weight of history hangs heavy over the industry. Warren Cude, a third-generation West Texas rancher, recently went through old equipment to prepare for the potential crisis. “We’re repeating history after 50 years. We didn’t learn from the first time and we let those facilities go and now we’re having to do everything again to combat something we eradicated 50 years ago,” Cude said.

With the fly now so close to the border, the race to contain this parasite is more urgent than ever.