An outbreak of H5N2 avian influenza on a large farm in central Minnesota's Meeker County has raised the state's tally of outbreaks to four this week and nine in a little more than a month.
The affected farm has 310,000 turkeys, far more than any of the previously affected sites, state and federal officials reported today. Meeker County lies just east of Kandiyohi County, the site of two outbreaks, and just south of Stearns County, which has had three.
Like the preceding incidents, this one was heralded by increased turkey deaths, which prompted testing by the University of Minnesota Veterinary Diagnostic Laboratory, according to the Minnesota Board of Animal Health (MBAH) and the US Department of Agriculture (USDA). The results were confirmed by a USDA Animal and Plant Health Inspection Service (APHIS) lab in Iowa.
One of 12 barns hit
Beth Thompson, DVM, JD, assistant director of the MBAH, said the virus struck just 1 of 12 barns on the farm. The standard response to an outbreak is to euthanize all birds on an affected farm, but in this case, she told CIDRAP News, "We are going to work with USDA on whether or not that whole site has to be depopulated or if it can be considered two separate flocks." For other purposes the farm has been considered to have two different flocks, she said.
Thompson said she wasn't sure how close the Meeker County farm is to the outbreak sites in Kandiyohi and Stearns counties. Officials have established a 10-kilometer-wide control area around the farm and will check all poultry flocks inside it.
Officials believe wild waterfowl carry the virus, but how it is getting into the turkey barns is still a mystery, Thompson said. The MBAH and USDA are putting together a team of investigators to assess the outbreaks "site by site" to try to find the answer, she added.
Investigators have not yet found any connection between the various farms, she said. "Whether it be feed trucks or people that bring in fuel or even workers, we haven't found any connection at this point. I grew up on a farm, and when you start thinking about the number of vehicles that come into a farmyard in a week, it is going to be a big task for these folks who are coming to take a look."
When asked about the possibility of deliberate contamination, she said, "You can't cross that off the list of possibilities, but it seems to be such a slight possibility for us."
Minnesota is the nation's leading turkey-producing state, said to produce 46 million birds per year. The eight outbreaks reported through yesterday involved farms housing a total of 373,000 turkeys, all of which were destroyed or are slated to be destroyed. If the Meeker County farm is completely depopulated, the toll will rise to close to 700,000 birds.
H5N2 confirmed in Ontario
In other developments, Canadian officials confirmed today that an avian flu outbreak on a southern Ontario turkey farm was caused by the same H5N2 virus that's attacking US poultry and that caused an outbreak in British Columbia in December, according to a Canadian Press story.
The Canadian Food Inspection Agency said 7,500 of 34,000 turkeys on the affected farm died, and the rest will be euthanized, the story said. A total of nine farms in the area have been quarantined, but the outbreak has affected only one.
The H5N2 virus has not been known to infect humans.
MBAH outbreak updates
Apr 8 USDA APHIS statement
Related Apr 7 CIDRAP News story
Apr 8 Canadian Press story