MINNEAPOLIS » A strain of bird flu that’s deadly to poultry has been found in a Minnesota commercial turkey flock but the risk to humans is low, state and federal officials announced Thursday.

It’s the same highly pathogenic H5N2 strain of avian influenza that’s been confirmed in backyard and wild birds in Washington, Oregon and Idaho, but it’s the first appearance of the strain in the Mississippi flyway, said Dr. Bill Hartmann, Minnesota’s state veterinarian.

The virus devastated a flock of 15,000 turkeys in western Minnesota’s Pope County. Fewer than 100 were still alive by Thursday, Hartmann said. The flock has been quarantined and the remaining birds were being killed. No other commercial flocks are nearby, he said, but "backyard flocks" within a 10-kilometer area were being tested for the disease.

"We’re encouraged that we’ll be able to prevent the spread of the disease," Hartmann said. "We should be able to contain this without much difficulty."

The virus is carried by wild waterfowl that aren’t sickened by it. The incubation period is about 21 days.

"If we can get through the next 21 days without finding anything, we should be in good shape," Agriculture Commissioner Dave Frederickson said.

Minnesota is the nation’s top turkey producer, with industry groups claiming to produce some 46 million turkeys each year worth around $750 million. Frederickson said about 8 percent of that production, or $92 million worth, was exported in 2013.

Frederickson acknowledged those exports could take a hit, as poultry exports from the Northwest already have.

"We’re very cognizant of that," Frederickson said. "We can only prepare for the worst and hope for the best."

Health Commissioner Ed Ehlinger said the only humans at risk were four people who worked directly with the infected flock and they will be monitored. However, no human infections from this strain have been detected anywhere, he said.

"There are no food safety concerns at this time," Ehlinger said. "This is not a threat to the general public."

Hartmann said he was prohibited by law from identifying the farm or saying where it’s located in Pope County.

Nearly all commercial turkey operations keep their birds inside large barns and they never go outside. Hartmann said that was the true for the affected farm, too. He said turkeys in only one of the farm’s four barns got sick. Farm workers found 70 dead turkeys Feb. 26 and notified the state the next day when hundreds died. The state got confirmation of the virus from a U.S. Department of Agriculture lab Wednesday night, he said

The state veterinarian said it was possible the virus may have been tracked into the barns from fecal material left by infected wild birds. It’s also possible for infected waterfowl to transmit the virus to shore birds that might then get into a turkey barn, he said.