How A Nasty Parasite Called The Screwworm Is Literally Screwing With Beef Prices

The nasty New World screwworm that bores into the flesh and tissue of cattle, often killing them, is adding to a perfect storm of conditions fueling record beef prices at the grocery store.

These parasites are flies that lay eggs in open wounds. The maggots bore deep into the flesh of cattle and other livestock, “like a screw being driven into wood,” causing serious and often fatal infections, according to the USDA Animal and Plant Inspection Service.

Importantly, the screwworm hasn’t been detected in U.S. cattle herds in the current outbreak. But its rapid spread in Mexico prompted the USDA to close southern border ports to livestock trade in May, cutting off a key market for U.S. ranchers struggling to meet consumer demand for beef as the domestic cattle inventory at a 70-year low.

The Food and Drug Administration’s conditional approval this week of a cattle-only injection to treat and prevent screwworm infections also illustrates the urgency in limiting what many experts say is the almost certain migration of the screwworm to the southern U.S., with climate change playing a major role.

It’s not the only pressure fueling record beef prices at the grocery store, but the export halt adds another significant break in the supply chain that is being felt from local sale barns to grocery store aisles. Tariffs, especially the combined 76.4 percent duty on beef from Brazil, have further tightened the supply of beef in the United States.

“We’ve kind of hit this perfect storm,” Brady Blackett, a third-generation Angus cattle producer in Utah, told NPR. “There’s healthy competition for the cattle, and there’s not enough of them to fulfill the demand. And so it has driven prices to historic highs.”

Grocery store beef prices are up 13 percent from last year, with ground beef hitting a record high of $6.63 a pound in August, according to the Bureau of Labor Statistics. Ribeye, New York strip and T-bone steaks are a luxury for many Americans, ranging in cost from $10 to $30 a pound, depending on the USDA grade and whether they’re bought from a grocery store or butcher.

‘This Is The Moment Of Change’

Consumers are taking notice.

Ground beef has historically been one of the fastest-growing grocery sectors, but sales have plateaued after years of strong demand, even with the higher prices, according to the research firm Circana.

“We're seeing people opt away from beef,” Circana’s Chris Dubois told NPR. “For years, all we saw were increasing prices and increasing demand. And this is the moment of change.”

Circana’s research shows U.S. consumers bought percent more ground beef in 2024 than they did in 2023, but in recent weeks, sales have been up only 0.2 percent from the year prior.

In response to high prices, consumers are stretching their grocery budgets with meat extenders like Hamburger Helper and rice, up 14.5 percent and 7.5 percent, respectively, in August from the same time last year, according to Circana. Sales of beef alternatives such as cans and pouches of tuna, salmon and sardines have also risen, along with beans and boxed macaroni and cheese.

“Cost-of-living expenses are up. Eating and drinking expenses are up,” Sally Lyons Wyatt, who advises packaged food companies at Circana, told The New York Times. “Consumers are looking for foods that fill them up for the least amount of money.”

How Long Before Prices Moderate?

Price moderation isn’t expected anytime soon.

“We’re going to be in a tight supply situation, in an elevated price situation for the next two to three years, probably [through] the rest of the decade,” Derrell Peel, a professor in the department of agricultural economics at Oklahoma State University, told CBS MoneyWatch.

It takes time to rebuild cattle herds, even if ranchers were inclined to invest in expansion. With operations costs spiraling as well, it’s sometimes more profitable for ranchers to sell off young heifers as meat animals rather than keep them for breeding, Blackett, the Utah Angus producer, told NPR.

“There’s not a lot of incentive to rapidly rebuild the herd,” he said.

Why Imports From Mexico Matter

Given all that, the screwworm is just what the beef industry doesn’t need.

The national beef cattle herd has withered under prolonged extreme drought conditions in states like Texas that caused many ranchers to liquidate their herds.

“For them, the balance is, ‘Do I sell that animal now and take this record high check?’ Or ‘do I keep her to realize her returns over her productive life when she’s having calves?’” David Anderson, a livestock economist at Texas A&M, told The Associated Press. “And so it’s this balancing act, and so far the side that’s been winning is to sell her and get the check.”

U.S. cattle producers have traditionally looked to Mexico, with its vast forage areas, as a source for yearling calves that can be finished into high-quality beef for domestic consumption. Feedlot operators imported about 1.5 million young calves annually for years and make up about 3.3 percent of the U.S. calf population, according to the Drovers Journal.

Agricultural economist Bernt Nelson with the American Farm Bureau told The AP the loss of that many cattle is putting additional pressure on the supply that is helping drive prices higher.

Even if ranchers decided to raise more cattle to help replace those imports, it would take at least two years to breed and raise them. And it wouldn’t be clear if that is happening until later this fall when ranchers typically make those decisions.

“We’ve still got a lot of barriers in the way to grow this herd,” Nelson said. “Just consider that a young farmer who wants to add 25 bred heifers to his herd has to be prepared to spend more than $100,000 at auction at a time when borrowing costs remain high.”

There is typically a seasonal decline in beef prices as grilling season slows down into the fall, but those price declines are likely to be modest.

Why FDA Expedited Drug Approval

The FDA said its expedited conditional approval of the first drug to treat and prevent screwworm infestations, the potent antiparasitic drug, Dectomax-CA1, a doramectin injection, underscores the seriousness of the threat of screwworms.

The decision was based on the prior, full approval of the drug for treating other parasites, which established the drug’s safety for cattle and the human food supply, the agency said.

“We understand the urgency with which America’s farmers and ranchers are asking for tools to fight New World screwworm,” FDA Commissioner Dr. Marty Makary said in a statement, adding the accelerated approval “shows our dedication to rapidly advancing important animal medicines when they are needed most.”

The FDA said the sponsoring veterinary drugmaker, Kalamazoo, Michigan-based Zoetis, collects the data needed for full approval.

The parasite was a recurring problem for decades, but was successfully eradicated in the 1960s and 1970s through a combination of the release of sterile flies and robust surveillance.

A significant infestation in the Florida Keys in 2017 primarily affected deer, but also a stray dog in the mainland city of Homestead. It was controlled by the release of 153 million sterile flies.

1st U.S. Human Case Reported

The flesh-eating parasites can occasionally make people sick. In August, a Maryland resident who appears to have been infected while traveling to El Salvador, Patch previously reported. The person recovered, and investigators found no transmission to any other people or animals, according to Maryland health officials.

• Related: First Human Case Of Flesh-Eating Parasite Has MD Link

Countries where the parasite is endemic are seeing infections in both humans and animals, according to the Centers for Disease Control and Prevention.

The agency said people who travel to areas where the flies are present, have an open wound, spend time among livestock animals, or sleep outdoors, may be at greater risk of an infection, the agency said.

“You may see maggots around or in an open wound. They could also be in your nose, eyes, or mouth,” according to the CDC.

Symptoms can include:

• Feeling maggots moving within a skin wound or sore, ears, nose, eyes, or mouth;
• Seeing maggots around or in open sores;
• Painful skin wounds or sores;
• A foul-smelling odor from the site of the infestation;
• Unexplained skin wounds or sores that do not heal or worsen within a few days; and
• Bleeding from open sores.

The Associated Press contributed reporting.

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