On January 22, Clark County officials in Washington declared a public health emergency, leading up to Inslee's state of emergency declaration on Friday.
Measles is a highly contagious respiratory disease caused by a virus that is spread by direct contact with nasal or throat secretions of infected people.
There are 25 confirmed cases in Clark County, and a single known case in King County after a man in his 50s contracted measles and was hospitalized following a recent trip to Vancouver, according to a news release from Inslee's office.
One case also has been confirmed in King County, which is home to Seattle and one was confirmed Friday evening in Multnomah County, which is home to Portland.
There have been 30 recorded cases of the infectious disease in the state's Clark County - just north of Portland - in January. The health agency says that most people born before 1957 don't have to get the immunization because they were probably exposed to the virus and already immune.
People who choose not to vaccinate their children are underestimating the dangers of the illness, said Melnick, who himself had measles as a child, before the vaccine was commonplace.
The BC Centre for Disease Control, a part of the Provincial Health Services Authority, provides public health leadership through surveillance, detection, treatment, prevention and consultation services. Eighteen of them are young children aged between one and 10 years old. When the rashes appear, fever could go beyond 104 degrees Fahrenheit. One dose of the measles vaccine is about 93 percent effective at preventing measles.
Officials there say they expect more cases.
More information about measles can be found here.
Those who are infected have visited public places while contagious, including the Portland International Airport, health care facilities and schools.
Public health officials in Washington say 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. Serious complications such pneumonia and brain infections can arise from the disease in some cases.
Schaffner adds, "It's no joke". "You feel miserable", he said.