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Bird Flu Sweeps Through Minnesota, More Than 340,000 Turkeys Killed

Seven farms infected so far

Seven farms infected so far

A nasty case of the bird flu keeps spreading through Minnesota's turkey farms.

When a farm is infected, every single turkey has to be put down, and the whole farm is cleaned out and disinfected. Yesterday the state announced the sixth and seventh cases where that will have to happen.

See also: 2006 Bird Flu: "This Thing Just Continues to March"

Farmers figure out they've been hit primarily through one of two ways, according to Beth Hahn with the Minnesota Board of Animal Health.

"Unfortunately one of the first signs a producer may see is unexplained death loss," she says. "In an operation it's not unusual for a few birds to die every couple of days. However, when that number gets higher than what they usually see -- what we call an increased death loss -- that's when it becomes clear something's wrong."

The other indicator is silence.

"In a flock of birds there's usually a lot noise, but oftentimes in this case the birds get very quiet," she adds.

The USDA pays farmers for every bird they have to put down once the farm is confirmed and infected, but Hahn isn't sure who foots the bill for the cleanup and disposal of carcasses.

Out of an estimated 46 million turkeys raised in Minnesota each year -- the most of any state in the nation -- 343,000 have been euthanized or killed by the H5N2 bird flu.

Hahn says Minnesota and the feds are preaching preventative measures while they try to figure out how this thing keeps spreading.

"We've been working with epidemiologists to do a thorough investigation and right now we don't know much. We do know that ultimately wild birds are involved as a reservoir of influenza virus, but the specifics of how this virus got into these barns is part of our ongoing investigation."

Previous versions of bird flu haven't been this contagious. This case, involving the "highly pathogenic" H5N2 virus, is new for Minnesota.

Send news tips to Ben Johnson.