Washington declared a state of emergency on Friday due to a measles outbreak that has spread to over two dozen people.
Officials aren't certain where the outbreak started, but the number of cases in the neighboring Portland, Oregon, area have quickly grown since December.
Twenty-six of the confirmed patients have not been vaccinated. According to the Washington Post, researchers consider the Portland area a "hot spot" for infection due to a high number of nonmedical exemptions from vaccination.
After Gov. Jay Inslee declared a state of emergency in Washington, warnings were also issued in Oregon and Idaho. Inslee described the situation as an "extreme public-health risk that may quickly spread to other counties."
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.