Twin Cities grocery shoppers may have noticed a dearth of eggs this week, as prominent supermarkets — including Cub Foods — are grappling with a bird flu-induced disruption of their egg supplies.

“We have had some disruption in the local supply chain for shell eggs,” said Jeff Swanson, a spokesman for Eden Prairie-based Supervalu Inc., Cub’s owner. “We expect to be back to normal on supplies by next week.”

Cub is the Twin Cities’ largest supermarket chain. Lunds & Byerlys and Kowalski’s both reported similar egg supply interruptions. All three companies’ issues stem at least partly from bird flu woes suffered by Minnetonka-based Michael Foods, one of the nation’s largest egg suppliers.

The highly lethal avian flu is in the midst of wiping out around 18 million egg-laying hens in Iowa and nearly 1.6 million more in Minnesota. Grocery chains often rely on regional egg suppliers for maximum freshness and cost efficiency.

“We are still getting some eggs, but the supply will get a little thin in the next couple of days,” said Mike Oase, vice president of operations at Kowalski’s.

Aaron Sorenson, spokesman for Lunds & Byerlys, said, “Some stores still have a fairly strong supply, but in some stores it’s a little spotty.”

Cub, Lunds & Byerlys and Kowalski’s all stressed that the supply gaps are temporary, and that they are lining up new supply sources. “The key thing is that the consumer should not be concerned about an egg shortage,” said Supervalu’s Swanson.

Wal-Mart and Target spokesmen said their Minnesota stores aren’t experiencing shortages.

Meanwhile, the bird flu was reported Thursday at two more Minnesota turkey farms, bringing the total to 84 poultry flocks. About 5.6 million Minnesota birds — mostly turkeys, but also chickens — have been or will be wiped out by the virus.

The highly pathogenic H5N2 bird flu descended on Minnesota’s turkey industry in March and by last month began rolling through chicken farms in Iowa, Minnesota and Wisconsin. Of the 84 flocks in Minnesota stricken by the flu, only three have been laying hens.

But two of those egg farms had over 200,000 hens. A third in Nicollet County, which regulators disclosed Monday, had 1.1 million birds, one of the largest egg farms in Minnesota.

The loss of that Nicollet County flock has “definitely been a factor for Supervalu,” Swanson said.

The Minnesota Animal Health Board doesn’t disclose the names of farms hit by the flu. But Minnesota Pollution Control Agency records show that the only egg farm in Nicollet County with 1 million hens is owned by Michael Foods.

Oase said that Michael Foods is Kowalski’s main supplier. Sorenson said Lunds & Byerlys eggs primarily carry the label “Waldbaum Farms,” which is a Michael Foods brand.

Michael, purchased last year for $2.45 billion by Post Holdings, didn’t return phones calls. St. Louis-based Post, best known for its breakfast cereals, also didn’t return calls.

Last week, Post disclosed that Iowa egg farms housing 5.5 million birds — about 10 percent of Michael Foods egg supply — had been hit by the avian flu.

Iowa is the nation’s largest egg producer, and at least 25 percent of that state’s laying hens will likely be killed because of the flu’s spread. Minnesota is the eighth largest U.S. egg producer, and the three hen farms hit by the flu account for 14 percent of the state’s production.

While deadly to poultry, the bird flu is not a food safety hazard and is a low risk for human health. There is no evidence that any human cases of avian influenza have ever been acquired by eating properly cooked poultry products, according to the federal Centers For Disease Control.