A mumps outbreak in Washington state has grown to about 290 cases in five counties, health officials report.

Mumps is a viral infection spread through infected saliva. It can be prevented through the MMR (measles, mumps, rubella) vaccine.

The Washington State Department of Health is urging people to get immunized and to take steps to prevent further spread.

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“It’s especially important for you to take precautions during winter holiday social gatherings,” the department states on its website. “Avoid kissing, hugging and other close contact with anyone who is suspected of having mumps.”

As of yesterday, the state department of health reports 160 cases in King County, which includes Seattle. The Spokane Regional Health District said Wednesday that there are now 90 people in Spokane sick with mumps, CBS affiliate KREM reports. Officials also say at least 35 cases have been confirmed in Pierce County, 3 in Snohomish and 1 in Yakima County.

Other states to see recent spikes in mumps cases include Arkansas, Iowa, Indiana, Oklahoma, and New York.

While mumps in the United States is no longer very common, last year saw the largest number of cases nationwide in a decade.

In 2016, the Centers for Disease Control and Prevention reported 5,311 mumps infections in 46 states and the District of Columbia. For comparison, there were about 1,300 cases in 2015 and just 229 in 2012.

The CDC recommends children get two doses of the MMR vaccine, which is 88 percent effective. Recent outbreaks, including the current one, involve many who have been vaccinated, leading some experts to question whether a third dose is needed.

Symptoms of mumps include swollen, painful salivary glands, fever, headache, fatigue, and appetite loss. If you have been exposed to mumps and feel ill, stay home to help prevent the spread of the disease and contact your doctor. Symptoms typically show up 16 to 18 days after a person is exposed, but can appear up to 25 days later.

Most people with mumps recover completely within a few weeks, though it can become more serious. Complications include meningitis, hearing loss, and inflammation of the brain (encephalitis).