The number of confirmed measles cases in Washington state has grown to more than two dozen in so many weeks. Health officials expect the outbreak to grow.

A measles outbreak has spread to more than 30 people in Washington state in just a few short weeks. Health officials believe that number will continue to grow.

"We can expect to continue to see cases related to this outbreak for many weeks or many months," said Dr. Jeff Duchin with Public Health Seattle and King County. According to Duchin, it can sometimes take 21 days to show symptoms of measles.

Measles mainly spreads through the air after an infected person coughs or sneezes. It is highly contagious. Signs and symptoms include fever, rash, coughing, and red, watery eyes.

One case is confirmed in a King County man in his 50s. The other confirmed cases are out of Clark County in southwest Washington, mostly in unvaccinated children under the age of 18.

On Friday, Gov. Inslee declared a public health emergency in response to the measles outbreak.

Also see: 5 fast facts about Measles

Duchin encourages people that worry about contracting the disease to get a blood test or another vaccination.

"If you are not sure of your immunization status, you can go to your healthcare provider and have a blood test, which will let you know if you're protected against measles. You can also just get vaccinated if you're not sure because an extra dose of measles, mumps or rubella vaccine is perfectly safe," he said.

Measles is a highly contagious disease that can have serious complications, especially for high-risk groups such as small children and pregnant women.