Avian flu samples flood U's vet lab as outbreak escalates

Before the avian influenza outbreak killed hundreds of thousands of turkeys in Minnesota, one farm suspected the virus and one university lab confirmed the news.

Since that first case four weeks ago, technicians at the Veterinary Diagnostics Lab at the University of Minnesota work double shifts and weekends testing about 100 samples a day for the highly pathogenic H5N2 bird flu virus.

Lab workers went from doing routine tests that produced mostly negative results, to quickly detecting the virus in many of the samples. Farmers from around the state send in samples collected from the birds' trachea.

The lab breaks down the samples into genetic parts. Using a process called polymerase chain reaction, researchers extract RNA, which carries genetic clues to virus activity. A machine creates a graph that shows just how much virus there is in each sample.

Veterinary Diagnostic Lab supervisor Liz Wiedenman is looking for what she calls a "strong amplification curve" that could indicate a positive test for avian flu.

"Once the virus is detected in there, it'll start amplifying," she said. "The more virus that's there, the faster it amplifies and the sooner it shows up."

Since that first detection, around 700,000 turkeys have died of the virus, or have been destroyed to prevent its spread. The latest flock to be hit numbered 310,000 turkeys at a Jennie-O operation in Meeker County. The company says no infected birds have entered the food chain.

Even though the percentage of birds lost to avian flu is less than 1 percent of Minnesota's total production, the escalation worries animal health officials, who still do not know exactly how turkeys are contracting the virus.

Barns near the nine operations that have confirmed the virus in six Minnesota counties are sending in samples, as are any farmers who wish to have their flocks screened. Each barn sends two samples; each contains tracheal swabs from 10 birds. The sample seems small in barns housing thousands of turkeys, but Wiedenman said it's an efficient way for farmers to test their entire flock.

"We've increased the amount significantly over normal numbers," Wiedenman said of the tests. "Just because of this uptick in surveillance that they're doing just to make sure things are negative."

Rob Porter, professor in veterinary medicine and veterinary pathologist at the U of M lab, is responsible for breaking the news to farmers.

"They're not the most positive phone calls," he said of calls confirming H5N2 results. "This is not just an economic tragedy for these people, this is an emotional tragedy as well in terms of the farmers' relationship with their poultry."

It's important to farmers to know negative results as well so they're able to move eggs and turkeys to processing plants, Porter said.

Just one sample in 100 tests per day has produced a positive result over the past 10 days in the U's lab, according to Porter. But that one positive sample could mean the deaths of thousands of turkeys.

"One sample could come from a flock with 16,000 birds," he said. "If that sample is positive, that has tremendous ramification for that flock."

MPR News reporter Mark Steil contributed to this report.

Map: Avian flu in Minnesota