Washington is now facing the biggest measles outbreak the state has seen in decades.
Washington's secretary of health said Wednesday officials have identified 38 confirmed cases of the contagious disease and 13 suspected cases.
That's the highest number of measles cases Washington state has seen since 1996, when 36 people were infected.
And officials say the disease will likely continue to spread. Washington has already declared a state of emergency due to the outbreak, and warnings have also been issued in Oregon and Idaho.
Measles causes symptoms such as fever, rash and sometimes pneumonia. In rare cases, it can be deadly. The CDC says two doses of the measles, mumps and rubella vaccine is 97 percent effective against measles, on average.