One case has been confirmed in King County, where Seattle is located.
The majority of the cases involve children younger than 10.
"Measles is a highly contagious infectious disease that can be fatal in small children", Washington Governor Jay Inslee said in a statement.
Clark County is an area American Health authorities call an "anti-vaccination hot spot".
The B.C. Centre for Disease Control (BCCDC) says, so far, there have been no infections in B.C. due to the Washington State outbreak.
"Routinely we don't vaccinate children prior to the age of one, so infants are likely to be susceptible, especially after about four to six months of age", she says.
LOS ANGELES: A state of emergency was declared on Friday in the western U.S. state of Washington following a measles outbreak that has affected more than two dozen people, the majority of them children.
Public health officials in southwest Washington, just across the Columbia River from Portland, Oregon, said people may have been exposed to the unsafe disease at more than three dozen locations, including Portland International Airport, a Portland Trail Blazers game, an Amazon Locker location and stores such as Costco and Ikea. Public health officials are focused for now on preventing more exposures.
Clark County has already spent more than $100,000 trying to contain the outbreak, and staff is being pulled from other duties, including restaurant inspections, he said.
The Washington Military Department, the release says, is organizing resources to assist the DOH and local officials in easing the effects on people, property and infrastructure. "Fortunately, the measles vaccine is very effective". Those infected can spread measles to others four days before and four days after the rash appears. The typical recommendations are that children should get two doses of MMR vaccine, the first between 12 to 15 months of age and the second between 4 and 6 years old.
Anyone who has not been vaccinated is at risk of getting measles if you come into contact with someone who is contagious.