Sep 5, 2008 (CIDRAP News) – Agriculture officials in Idaho announced yesterday that they were investigating an outbreak of low-pathogenic avian influenza at a game farm in the southwestern part of the state after a federal lab confirmed the virus in pheasants.
The virus has been identified as subtype H5N8, according to a Sep 3 report that the US Department of Agriculture (USDA) filed with the World Organization for Animal Health (OIE). The farm contains about 30,000 game birds that are raised for hunting activities, the report said. Besides pheasants, the farm has chukars, partridges, and mallard ducks.
State officials quarantined the farm on Aug 29 but have not culled any birds at the site, located in Payette County. However, Larry Hawkins, a USDA spokesman, said 300 birds that the farm shipped to California for a bird dog event before the virus was detected were quarantined and culled, the Associated Press (AP) reported today.
The farm's owner did not report an unusual number of bird deaths, but in late August sent three dead pheasants to a lab at Pennsylvania State University for a diagnostic work-up, according to the OIE report. The lab found Pasturella and Mycoplasma in the samples. Routine tests also revealed avian influenza. Sequence testing at the USDA's National Veterinary Services Laboratory led to the H5N8 finding on Sep 3.
The virus seems to trace back only to the pheasant pen, which contains about 1,000 birds, the report said.
Officials have not determined the source of the virus but suspect that it came from contact with wild birds. Bill Barton, a veterinarian with Idaho's Department of Agriculture, told the AP that the pheasants were kept in an outside pen that was covered with plastic mesh. He said they could have been exposed to the virus from wild birds that flew or roosted overhead.
David Halvorson, DVM, a veterinary pathologist and avian flu expert at the University of Minnesota in St. Paul, told CIDRAP News that a wild-bird source of the virus sounds plausible. "They [the game birds] are like live decoys. They'll attract wild birds to their pens because of the feed and water," he said.
Though low-pathogenic H5N8 hasn't been seen in the United States over the past several years, there's nothing alarming about finding the virus at the Idaho farm, he said. "It's not unusual to find an oddball low-path virus."
Barton said the findings of the investigation will determine how long the birds should be quarantined and if culling is necessary, the AP reported. He said authorities are testing birds at farms within a 2-mile radius of the site and disinfecting the affected game farm.
Sep 4 Idaho Department of Agriculture press release