Raw oysters are the suspected source of a norovirus outbreak in King County.

Since January, up to 39 people have come down with the symptoms of norovirus, which can include diarrhea, vomiting, nausea, stomach pain, and fever, according to the Seattle King County Public Health Department.

Health officials say the oysters linked to the recent outbreak came from different bays and beds across the state, but the Washington State Health Department has temporarily banned shell fish harvesting in a portion of Samish Bay in northwest Washington.

"Raw oysters have long been recognized as a source of norovirus," said Dr. Meagan Kay, a Public Health medical epidemiologist. "Raw or undercooked oysters seem to be a particular problem."

She says shellfish can ingest norovirus if it's in the water.

Kay says every establishment linked to a shellfish sickness is inspected, but there are also steps you can take to protect yourself.

Instead of eating raw or lightly steamed oysters, she recommended eating those that have been thoroughly fried, baked, or cooked in a stew. Make sure the meat reaches a temperature of at least 145 degrees. Washing your hands frequently also helps.

Kay cautioned that norovirus is highly contagious. A person who contracted the illness by eating a contaminated oyster can spread it to other people.

The symptoms of norovirus usually subside within a few days.