Washington state health officials say a salmonella outbreak linked to pork products has grown to 134 cases in 10 counties.

Early tests show a connection to a slaughter facility in Graham, Washington.

The federal Centers for Disease Control and Prevention has joined the state health department in its investigation into the outbreak. People eating pork are advised to cook it thoroughly.

Most of the illnesses -- 84 cases -- were in King County, while 24 cases were found in Snohomish county, 12 in Pierce County and five in Yakima County.

Health officials say exposure for many of the people who became ill was whole roasted pigs served at private events and restaurants.

Exposure to salmonella bacteria can cause fever, abdominal discomfort and vomiting.