SEATTLE (AP) -- Federal and state officials are testing wild birds in Washington state to see how far a type of avian influenza has spread.
Separate strains of the H5 virus were identified in a wild duck and a captive gyrfalcon in northwest Washington this month. Neither virus has been found in commercial poultry in the U.S.
State officials say the virus poses no apparent threat to humans, but highly pathogenic strains can be deadly to domestic poultry, and rarely, wild birds.
Officials are taking swabs from about 600 ducks and other waterfowl that are taken by hunters, said Don Kraege, with the state Department of Fish and Wildlife. They're focusing in Whatcom, Skagit, Snohomish, Thurston and Clark counties.
Kraege said officials want to know what percentage of the birds has it and to get a baseline to see how far the virus spreads.
An avian influenza outbreak earlier this month in British Columbia spread to several poultry farms there and has affected about 245,000 birds, the Canadian Food Inspection Agency said on its website.
The state's two confirmed cases are a captive falcon with the H5N8 strain of avian flu, and a wild duck with the H5N2 strain, similar to the strain found in poultry in British Columbia.
State officials discovered the virus in the pintail duck as they responded to a die-off of wild ducks at Wiser Lake in Whatcom County. A respiratory fungal disease has so far killed about 120 ducks, Kraege said. The duck had the virus but likely died of the fungal disease, he said.
Federal agricultural officials have also confirmed the presence of the H5N8 virus in guinea fowl and chickens in a backyard poultry flock in Winston, Oregon.
State and federal officials advise people -- especially commercial poultry operations -- to report sick birds and take steps to assure their flocks don't come into contact with wild birds.