A quickly growing measles outbreak that began in southwest Washington, near Portland, Oregon, has caused local officials and the state’s governor to declare a public health emergency. The latest outbreak comes as 2018 saw the second highest number of reported measles cases (349) in the U.S. since 2000, according to a recent update from the Centers for Disease Control and Prevention (CDC). 

As of Jan. 30, 38 confirmed and 13 suspected cases of measles had been identified in Washington’s Clark County, just across the Columbia River from Portland, since the start of the new year. Last week, one measles case was also confirmed in King County, where Seattle is located, and in Oregon’s Multnomah County, home to Portland, respectively. 

In the Clark County outbreak, 27 of the cases were between the ages of 1 and 10. Thirty-four of the total identified cases had not been vaccinated against measles, while the immunization status of four cases was unverified, Clark County Public Health reported on its website. One person had been hospitalized so far. The more than three dozen public locations in the area where people may have been exposed to measles include health facilities, schools, churches, stores, and a Portland Trailblazers basketball game. 

In the 2017-2018 school year, nearly 8 percent of children in Clark County were exempt from vaccine requirements for kindergarten entry, including the recommended two doses of measles, mumps, and rubella (MMR) vaccine, according to state data, the Washington Post reported. Only 1.2 percent of these children had a medical reason for their exemption. 

Nationwide, there were 17 measles outbreaks reported in 2018, defined as three or more linked cases. The latest outbreak in Washington follows lingering outbreaks in parts of New York and New Jersey that contributed to 2018’s near record total of U.S. reported measles cases since 2000, topped only by 667 cases in 2014. According to CDC, cases in the New York and New Jersey outbreaks have occurred primarily among unvaccinated people in Orthodox Jewish communities and have been associated with travelers who brought measles back to the U.S. from Israel, where a large outbreak is ongoing. 

Noting a 30 percent increase in measles cases globally, the World Health Organization (WHO) recently named vaccine hesitancy, which it described as “the reluctance or refusal to vaccinate despite the availability of vaccines,” as one of 10 threats to global health in 2019. During the first six months of 2018, more than 41,000 children and adults in Europe were infected with measles, surpassing the annual total of European cases reported in any previous year this decade, WHO reported in August of 2018. Additional information on measles for health care professionals, including clinical features, complications, diagnosis and lab testing, and vaccination recommendations, is available on CDC’s website.