The unprecedented U.S. bird flu outbreak that is centered in Minnesota is likely to stick around for a few years and possibly damage poultry farms across the nation, a top U.S. veterinary official said Thursday.

"This is something very unusual, where we have seen bird flu adapt so well, " John Clifford, chief veterinary officer for the U.S. Department of Agriculture (USDA), told a Minnesota House agriculture committee.

The House voted unanimously late Thursday to pony up almost $900,000 to help state agencies battle the bug. For lost birds in Minnesota alone, the flu's tab is already in the tens of millions of dollars.

The USDA has already spent $15 million helping stricken farmers, and that's just the beginning.

The flu was confirmed Thursday on four more Minnesota turkey farms, bringing the total to 26, with more than 1.6 million birds affected. The disease also was reported at a commercial turkey farm with 126,000 birds in western Wisconsin's Barron County; and at a back yard flock of 40 birds in eastern Wisconsin.

Plus, another outbreak at a South Dakota turkey farm was disclosed, bringing the number in that state to four. Altogether, at least 12 states have been affected by the virus.

"It's something in North America that we may have to live with for a few years," Clifford told legislators. "It will very likely reoccur later this fall, and not just in Minnesota, but in all four flyways," he said, referring to major waterfowl migration routes across North America. "It can impact poultry across the United States."

The lethal H5N2 bird flu is believed to originate in waterfowl that don't get sick from the virus but spread it through their feces. Once it's in a waterfowl population, the virus can persist for three to five years, Carol Cardona, veterinary biosciences professor at the University of Minnesota, said at the hearing.

Clifford, based out of Washington, D.C., has been in Minnesota to assess the bird flu situation since Tuesday. He's met with farmers and executives from turkey companies, including Jennie-O, a division of Hormel Foods and one of the nation's largest turkey processors. The USDA has sent dozens of employees to Minnesota to help state animal health regulators respond to the virus.

Domestic turkeys are particularly susceptible to the H5N2 virus, and Minnesota is the nation's leading turkey producer, churning out about 46 million birds a year. Roughly one-third of Minnesota turkey deaths come directly from the flu, while the rest come from the policy of killing all birds on a farm — even those not infected — out of precaution.

For those birds lost through culling, the USDA pays an indemnity to farmers. "It doesn't make growers whole, but it helps," Minnesota Department of Agriculture Commissioner Dave Frederickson told legislators.

Clifford said the USDA has spent about $15 million in emergency funds on bird flu in Minnesota, most of it in indemnity payments to turkey growers.

USDA officials couldn't say how many farms hit in Minnesota have gotten USDA payouts so far. But the payments will surely rise, and Clifford said in an interview with the Star Tribune that he expects the USDA to come through with more money.

On average, it takes $2 million to euthanize a flock, Clifford said, including costs such as disinfecting barns after turkey "compost" is removed. The birds are composted for 28 days with wood chips and manure, which kills the virus, animal health officials say. The compost that's left is usually spread on farm fields. It looks "something similar to large chunks of dirt," Frederickson said.

The payouts for dead birds depend on market prices and the age of the birds; the older and closer to being slaughtered, the higher the payment. The virus is particularly striking older turkeys. The payout for a mature bird near slaughter might be about $25, Clifford said.

Farmers bear the cost of birds killed directly by the flu, as insurance for avian disease is rare. Direct losses for Minnesota farmers were more than $15 million for the first 900,000 birds killed, according to the Minnesota Turkey Growers Association. Also, farmers hit by the bird flu face a huge business interruption: Their barns can be out of commission for months.

Thursday, the USDA confirmed new outbreaks at turkey farms in Stearns, Kandiyohi, Otter Tail and Roseau counties. The Roseau outbreak is the first in Minnesota's far north; the outbreaks in Stearns and Kandiyohi are respectively those counties' sixth and fifth. They are the state's two biggest turkey-producing countries.

Jennie-O reported on its website that the newly afflicted Kandiyohi and Otter Tail sites are farms that supply it with turkey. The Stearns County and Barron County, Wis., farms are owned directly by Jennie-O. So far, 18 Jennie-O suppliers, including company-owned farms, have been hit.

The House voted unanimously late Thursday to suspend its rules so it could quickly take up and approve the $893,000 for avian flu emergency response. The money is divided into two pots: $514,000 for the state commissioner of agriculture, and $379,000 to the state Board of Animal Health.

"This will pay for immediate emergency spending, overtime pay for the people who are working on this right now," said Rep. David Bly, DFL-Northfield. "This is an active thing happening right now, and we need to address it."

Bly said additional money would be included in a broader agriculture funding bill that's also moving through the legislative process. The emergency funding dollars still must be approved by the state Senate and signed by Gov. Mark Dayton.

Star Tribune staff writer Patrick Condon contributed to this report.

Mike Hughlett • 612-673-7003