An egg-laying operation in southern Minnesota with 1.1 million hens has been hit by the bird flu, the largest single incident in the state since the lethal virus surfaced two months ago.

The big hen flock in Nicollet County is one of eight more Minnesota farms with presumptive positive tests for the H5N2 virus, bringing the total to 80, the Minnesota Board of Animal Health announced Monday. The Nicollet County farm — one of the state’s largest — is the third Minnesota egg operation stung by flu.

Animal health regulators, citing state law, don’t release the names of stricken farms.

The bird toll in Minnesota is now at least 5.34 million, including 1.57 million chickens. Meanwhile, a total of over 18 million birds — egg-laying chickens mostly, but turkeys, too — have been struck by the flu in Iowa. Another 1.8 million chickens and turkeys have been afflicted in Wisconsin.

Turkey flocks have borne the brunt of the flu in Minnesota, with about 8 percent of the state’s annual turkey production wiped out so far. Minnesota is the nation’s largest producer of turkeys, usually churning out about 46 million birds.

Poultry industry and animal health officials are hoping that the warmer weather of the past week — which is expected to continue this week — will slow down the flu’s pace.

“I think this week should be a good indicator of where we are at,” said Steve Olson, executive director of trade groups for Minnesota’s turkey growers and egg farmers.

It takes more than eight days for a flock to be exposed to the flu, show symptoms and then be confirmed for the virus. So, Monday’s cases would have likely germinated before the recent warm-up.

The bird flu is not a food safety hazard and is considered a low risk for human health. The virus hasn’t sickened anyone in the United States since it was first reported during the winter.

The flu has hit far more turkey farms than egg farms, but the latter account for the biggest single losses.

There are usually fewer birds on turkey farms than at egg-laying operations. The largest Minnesota turkey outbreak involved 310,000 birds at a Jennie-O facility in Meeker County, and most operations have fewer than 100,000. By contrast, the smallest of three Minnesota egg operations hit by the flu had 202,000 birds.

Those three egg farms, including the Nicollet County operation, represent about 14 percent of Minnesota’s laying hens.

Minnesota has the nation’s eighth-largest egg-laying industry. Iowa has the largest, and the bird flu has surfaced at farms representing over 25 percent of that state’s egg industry.

The single largest farm hit by the bird flu is an egg operation in Iowa with 5.5 million birds, owned by Rembrandt Foods, which is in turn owned by Minnesota businessman Glen Taylor, whose holdings include the Star Tribune.

The flu often kills just a minority of the birds on each farm, but all turkeys or chickens on a site are usually killed out of precaution.

Meanwhile, U.S. Sens. Amy Klobuchar and Chuck Grassley, respectively of Minnesota and Iowa, on Monday led a bipartisan group of senators addressing the bird flu outbreaks. The 15 senators wrote a letter to the Senate Appropriations Committee to ensure that the U.S. Department of Agriculture receives necessary funding to battle the avian flu.