H5N2 shows up on Arkansas turkey farm

US officials announced today that highly pathogenic H5N2 avian influenza has surfaced on a turkey farm in northwestern Arkansas, marking the fourth outbreak and the third state in the central United States affected by the virus in the past week.

The virus struck a commercial flock of 40,000 turkeys in Boone County, Ark., which borders Missouri, the US Department of Agriculture's Animal and Plant Health Inspection Service (USDA APHIS) said in a statement today.

Also, recent tests performed on wild birds near an affected farm in Minnesota—the first central US state to experience an H5N2 outbreak—came back negative for avian flu viruses.

Series of Mississippi Flyway outbreaks

The new outbreak follows three other recent turkey farm outbreaks—the one in Minnesota that was announced last week and two in Missouri, reported Mar 8 and yesterday.

The Minnesota outbreak was the first high-path H5N2 appearance in the central United States and the Mississippi Flyway, after it cropped up in wild birds and backyard flocks in Washington state, Oregon, and Idaho in the past few months. In November the virus struck poultry farms in southern British Columbia.

APHIS said it is working with the Arkansas Livestock and Poultry Commission on a response to the new outbreak, including quarantining the farm and destroying the turkeys to stop the virus. As with the previous outbreaks, officials said there is little danger to human health, since the virus has not been known to infect humans.

Arkansas is the nation's third-leading turkey-producing state, after Minnesota and North Carolina, and is home to Tyson Foods, the nation's biggest chicken company. The recent US avian flu outbreaks have already prompted dozens of countries to ban poultry imports from affected states or even from the United States as a whole.

Reuters reported today that shares of Tyson and other poultry companies, including Pilgrim's Pride Corp. and Sanderson Farms Inc., fell because of worries that the Arkansas outbreak will further limit US trade with Asia and Latin America.

Wild Minnesota birds test negative

In other developments, a Minnesota official said today that preliminary testing of samples from wild ducks near the Minnesota turkey farm recently hit by H5N2 has revealed no evidence of the virus.

Michelle Carstensen, PhD, wildlife health program supervisor for the Minnesota Department of Natural Resources (DNR), said that in response to the outbreak, the DNR ran an aerial survey of wild birds on open water within 15 miles of the outbreak site (see the downloadable map at the top of the column at right). Given the season, there was little open water and few waterfowl, but scientists found one flock of mallards and three groups of swans.

The team then collected environmental samples from the mallards and tested them, and the results were all negative for avian flu, she said. She added that the staff was collecting more samples from the mallards and the swans today, aiming to establish a baseline of information on what microbes are present before migratory birds start arriving with the spring migration. "Now with changes in the weather, migrant birds are moving in, so the system is changing rapidly," she noted.

Carstensen said that despite the often-mentioned view that H5N2 is being spread by wild birds, it's unlikely that wild birds from the West Coast caused the Minnesota outbreak, given that it's still winter.

"I am saying that it is extremely unlikely that wild, migratory birds moved from the Pacific West coast into Minnesota in February and exposed the flock in Pope County to HPAI H5N2; it is further unlikely that infected wild waterfowl moved from Minnesota to Missouri or Arkansas in recent weeks given the time of year," she commented by e-mail.

"Migratory waterfowl travel in north-south flight lines and they move south in fall and north in spring; birds returning to Minnesota would be coming from the Gulf Coast states, South America, Caribbean, etc," she added.

Carstensen said it's too early to comment on how the virus might have reached the Minnesota farm, as an epidemiologic investigation of the outbreak is far from complete. The investigation is being led by the USDA and the Minnesota Board of Animal Health.

See also:

Mar 11 APHIS statement

Mar 11 Reuters story

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