The relief from sky-high egg prices may be starting to crack.

Cal-Maine Foods, the largest egg producer in the country, reported Tuesday that a Kansas facility had an avian flu outbreak in about 1.6% of the company’s total flock, or about 684,000 laying hens. Meanwhile, data from the U.S. Department of Agriculture shows dozens of commerical flocks have been hit hard by the virus in recent months.

The latest bird flu outbreak has stirred concerns that egg prices – which had finally started to settle after reaching nearly $5.50 a dozen late last year – may start spiking again.

“Seemingly every day there is another announced infection site, which not only physically reduces the actual number of egg layers, but also casts a negative psychology over the entire egg market,” Kevin Bergquist, Wells Fargo Agri-Food Institute sector manager, said in a written statement. “The reaction to supply stress is price increase.”

Is there another avian flu spike?

More than 72.5 million birds have been killed in 2022 and 2023 to stem the spread of the virus, according to the U.S. Department of Agriculture.

After a lull in infections, the agency's data shows we’re in the midst of a fall spike. The number of birds killed has risen from 1.4 million in October to 8 million in November and more than 4 million in the first few days of December.

The virus “is expanding at a very similar pace to the previous major outbreak, so it is serious,” Bergquist said. He described the current virus mutation as “one of the more virulent and contagious, which is not good for the entire poultry industry.”

The migration of wild birds is likely the cause of the most recent spike.

"They're often mixing with other birds and allowing for that amplification, ping-ponging of the virus to occur,” said University of Minnesota School of Public Health Professor Jeff Bender. “Then, (it’s) spilling over into those very susceptible birds like our turkeys and chickens.”

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Why are egg prices going back up?

Federal data shows egg prices have dipped more than 22% over the past year as egg producers worked on rebuilding their supply. A USDA report released earlier this week quotes combined regional large egg wholesale prices at $2.06 a dozen – close to the three-year average but far below last year's prices.

Egg prices already had been expected to rise this winter because of seasonal demand, and the spike in avian flu infections could compound those increases.

“Christmas is one of the times where egg consumption goes up for holiday meals, the eggnog and all that kind of stuff,” said Yuko Sato, a poultry extension veterinarian and diagnostic pathologist at Iowa State. “So naturally, every year, the egg prices go up during Christmastime or holiday season.”