OLYMPIA, Wash. – Highly pathogenic H5 avian influenza was confirmed in another flock of domestic birds in Washington State.

The virus was found in birds from a backyard poultry flock near Benton City, the Washington State Department of Agriculture (WSDA) reported. The agency said the flock of 150 birds includes domestic waterfowl with access to the outdoors. The owner contacted WSDA after about 50 birds died during the past week. WSDA said the virus is similar to the one found in Washington captive Gyrfalcon in December, however additional testing will be done to confirm the strain. Washington State Univ.'s Washington Animal Disease Diagnostic Laboratory in Pullman, Wash., confirmed the H5 virus.

“We have a vigorous response plan but this development demonstrates how important good biosecurity can be, especially for backyard bird owners,” said Dr. Joe Baker, state veterinarian. “We have not diagnosed the virus anywhere else in our domestic poultry population, but the presence of the virus in migratory waterfowl is a risk to backyard poultry. One step owners should take is preventing contact between their birds and wild birds.”

In December, two separate strains were identified in Whatcom County, Wash.: H5N2 in northern pintail ducks, and H5N8 in captive Gyrfalcons that were fed hunter-killed wild birds. No commercial poultry flocks have been affected.