The highly lethal bird flu has struck a Hormel Foods turkey farm, the ninth and likely most deadly Minnesota outbreak yet.

The outbreak marks the first time Austin-based Hormel, owner of the well-known Jennie-O turkey brand, has acknowledged the fast-spreading bird flu’s impact.

A flock of 310,000 turkeys in Meeker County has been stung by H5N2 bird flu, regulators said Wednesday. The virus surfaced in one of 12 barns on the massive Hormel site. It’s not clear yet if all 310,000 birds will be killed. In the previous eight outbreaks, all birds on the farms have been euthanized as a safety precaution.

So far, 340,000 turkeys have died since the bird flu descended on Minnesota in early March, about two-thirds of them by precautionary euthanization. If all of the birds on the Hormel site end up being killed, the death toll would rise by 91 percent.

“On an annual basis, that’s still a pretty small number,” said Steve Olson, executive director of the Minnesota Turkey Growers Association. “But certainly when we are getting above a half-million birds [destroyed], that’s getting pretty significant.”

Minnesota’s turkey industry, the nation’s largest, churns out 46 million birds a year.

The bird flu has a low human health risk and does not pose a food safety issue because affected birds are not allowed into the food chain, health experts say.

The H5N2 flu first hit a Pope County, Minn., farm in early March, and has snowballed in the past two weeks. Regulators say state law prohibits the release of an infected farm’s exact location. Three earlier outbreaks — one each in Stearns, Kandiyohi and Lac qui Parle counties — were at farms producing turkeys for Jennie-O, Hormel said Wednesday.

On the Jennie-O website, the company said the turkeys affected by the bird flu make up a small percentage of the company’s production. Hormel declined to make an executive available for an interview.

Like other farms hit by the bird flu, Hormel is working on a “flock plan” for the Meeker County farm with the U.S. Department of Agriculture regarding the disposition of birds in the 11 barns not hit by flu.

Hormel is the nation’s largest turkey processor and relies on farms in Minnesota and Wisconsin for most of its supply. Some turkeys come from company-owned operations like the one in Meeker County, others from independent farmers or farmers under contract with Jennie-O. A contract farmer raises company-owned turkeys, uses company-owned feed and provides the facilities and the labor.

“The unique thing about the turkey industry is that it’s a pretty integrated industry,” said Dale Nordquist, a University of Minnesota Extension economist. In other words, turkey processors like Hormel can have a large role in production.

The Hormel operation in Meeker County is one of the largest turkey farms in Minnesota, if not the largest, Olson said. Turkey operations hit by the flu before the Meeker County outbreak had three to five barns.

Commercial turkey operators pack several thousand birds into a barn, which can work against them during an outbreak.

“I think a greater number of birds makes it easier to speed the infection from one bird to another,” said Robert Porter, a professor of veterinary population medicine at the University of Minnesota. “I think the proof is in these outbreaks.”

However, he noted that the concentration of several barns on one farm has so far not been an issue. In most of the outbreaks, the flu has been detected in only one barn at multi-barn farms. Animal health experts have said they don’t believe the flu is being spread from farm to farm.

The avian flu is believed to be spread by migratory waterfowl that carry the virus but are not sickened by it. The virus spreads through wild bird feces, which are somehow being tracked into barns despite farmers’ biosecurity measures.