New avian flu cases have cropped up in Polk County, Ore., and Yakima County, Wash., after a two-week lull that suggested the deadly outbreak was beginning to ease in the Pacific Northwest.

A backyard flock in Yakima County tested positive for highly pathogenic avian influenza on June 7, and a second Yakima case was confirmed June 10. In Oregon, HPAI was confirmed in a backyard flock of ducks and geese west of Salem after the flock's owner one dead bird and others that were showing symptoms.

"The virus continues to be present in all corners of our state,” Washington State Veterinarian Dr. Amber Itle said. “It’s so important we remain vigilant.”

Related: Bird quarantine lifted in Oregon county

The new cases come as the Oregon Department of Agriculture lifted a bird quarantine in the Eugene area that had been imposed May 17 after the agency completed two rounds of testing. While HPAI spread rapidly throughout the region in May, the Yakima detections were the first the state announced since late May.

Meanwhile, Oregon State University specialists are telling wild bird enthusiasts that it's OK to leave up bird feeders, as the risk to native songbirds is low.

"We still recommend that everyone practice good everyday hygiene for the wild birds by regularly cleaning feeders and birdbaths because of salmonella, mold and the ‘everyday’ health concerns that we can combat with regular cleaning of surfaces that get a lot of use," OSU specialist Dana Sanchez said.

Related: UC expert: Protect poultry from migrating birds

Outbreaks of the H5N1 bird flu have devastated commercial poultry operations in the Midwest this year, killing over 37 million chickens and turkeys. HPAI has yet to show up in commercial flocks in the West, but the disease has been found in backyard flocks throughout the region, including in Colorado, Wyoming, Montana, Utah and Idaho.

Source: Washington State Department of Agriculture, Oregon Department of Agriculture, Oregon State University, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.