SALEM, Ore. — State wildlife officials say some Western Oregon songbirds are contracting a fatal bacterial infection from bird feeders.

Salmonella, the bacterium that can be found in undercooked eggs and pork, is usually found in minuscule amounts in birds. But dirty bird feeders can create an unnatural and unhealthful place for birds to eat, officials said.

"Birds can carry salmonella at low levels," said Colin Gillin, state wildlife veterinarian at the Oregon Department of Fish and Wildlife. "Then it gets concentrated in organic matter in a feeder. If you don't clean the feeders, it spreads from feeder to feeder."

Western Oregon residents have been reporting songbird die-offs to the Fish and Wildlife Department since early winter.

Wildlife biologists from California to Alaska have reported similar outbreaks.

The disease — salmonellosis — gets into a bird's bloodstream and causes abscesses in organs. The species most severely affected include American goldfinches, pine siskins and purple and house finches.

Salmonellosis usually is spread when birds eat fecal-contaminated feed or when their eyes come into contact with the feeder itself.

There are no reported cases of humans contracting the bacteria from a feeder used by wild birds, said Bob Sallinger, urban-conservation director of the Portland Audubon Society.

Wildlife officials, however, said pets can become infected, especially cats that catch and eat sick birds around feeders.

People can prevent the disease's spread by not feeding birds for a while or cleaning their feeders often.