Measles is known to be highly contagious - in other words, very easy to contract if an unvaccinated, non-immune person is exposed. One person has been hospitalized in the outbreak.
There were almost 350 measles cases recorded past year in 26 states and the District of Columbia, the second greatest number since the disease was eliminated in 2000.
Most of the cases have been in children younger than 10, according to a statement from the Clark County Public Health Department in Washington. One adult is infected, and the rest are teenagers.
A public health emergency in Washington State is catching the attention of Idaho Health Officials after dozens of confirmed measles cases. Authorities in neighboring OR and Idaho have issued warnings.
The most recent figures available from Washington State Department of Health as of Saturday indicate the number of confirmed cases has since risen to 32 across two counties since January 1, with the majority of cases being in children 10 years old and younger.
Measles was declared completely eliminated within the U.S.in 2000 due to the country's widespread vaccination program.
But measles is still a big problem in other parts of the world. The agency noted the outbreaks were associated with travelers who brought measles back from Israel.
In the USA last year, there were 17 outbreaks and about 350 cases of measles.
Officials still are not sure where this Pacific Northwest outbreak began. The first known patient sought medical care on December 31, but it isn't known if other people may have gotten sick before that and did not seek treatment.
According to the Clark County Department of Public Health's investigation, at least 30 of its recorded cases were in people who were not immunized against the virus.
Last week, a person infected with measles attended a Portland Trail Blazers home game in OR amid the outbreak. While the King County website says the patient, a man in his 50s, is a "suspected case", the governor said in a news release it is a confirmed case of measles.
"Vaccines are really important to keep kids and other people healthy and safe".
NY state is facing its worst outbreak in decades, with more than 200 cases.
"It's all hands on deck. Many state courts have weighed in and the right to practice a religion, the right to choose, does not include the liberty to expose a community or a child to a disease", Harris said. "These costs could have been prevented if we had everybody vaccinated".
A recently-introduced bill in the Washington State Legislature would put a stop to personal exemptions for the measles vaccine in children.
"It's their lives on the line, honestly, if they're not vaccinated and something like this happens, then what am I going to do to save them?" Vaccine exemptions in OR increased from just 1 percent in 2000 to 7.5 percent in the 2016-2017 school year, according to PBS.
Data on Portland's vaccination rate for both shots wasn't immediately available. The CDC says the measles vaccine is 97% effective if the first dose is given at one year old and the second at five years old.
The groups often spread misinformation claiming a link between vaccines and autism. The vaccine-exemption rate in Clark County for non-medical reasons was high, at 7.5 percent, Armstrong said. Patients remain contagious for four days after they develop the rash.
The airborne illness is so contagious that someone could contract the measles even two hours after a sick person leaves an area. "However, the majority of people exposed to measles are not at-risk of developing the disease since most people have either been vaccinated or have had measles in the past, before vaccination became routine". Those people stayed home and later got ill, Armstrong said.
Washington state officials are now beginning the arduous and costly task of tracking down everyone who might have been exposed to the infection and cautioning them to be on the alert for symptoms, including runny nose, red eyes, fever and rash.