Now, 35 cases have been confirmed in Clark County, a southwestern county that includes Vancouver, and 11 potential cases are awaiting confirmation.
At least one person has been hospitalized in Washington. Health officials are looking at a number of other suspected cases.
The majority of the infections are in children younger than 10 years old.
Health experts say measles is one of, if not the most contagious virus out there. OR officials didn't provide the age of the adult infected there.
Although no cases of measles related to an outbreak in Washington state have been reported in B.C., the province's centre for disease control (BCCDC) is warning British Columbians about travelling to the affected communities. Authorities in neighboring OR and Idaho have issued warnings.
And once there are pockets of disease, the possibility of a measles outbreak increases.
In an effort to stop the spread of the illness, the Health Department and partners have provided more than 16,000 vaccinations.
The hospital has restricted visitation to labor and delivery, mother-baby and neonatal intensive care units, citing the rise in measles and influenza cases. To find a public health unit anywhere in the province, see the site finder on ImmunizeBC.ca. The Oregon case is linked to the outbreak in Clark County, health officials said. Ninety per cent of people exposed to measles who have not been vaccinated will get it, health officials said. However, vaccination again measles is very effective at preventing illness.
"We actually don't have any confirmed cases here in Lane County", said Jason Davis, Lane County Health and Human Services Public Information Officer.
As the MMR vaccine can not be administered until age 1 this leaves these young infants at particular risk of contracting the measles if they come into contact with the virus.
"It's all hands on deck".
USA county-level nonmedical vaccine exemption rates, 2016-2017.
The best protection against measles is vaccination, the centre said. Clark County's vaccination rate is 78 percent, well below the 94 percent level necessary to protect people who can't get vaccinated for medical reasons.
In 2000, measles was considered eradicated in the United States, thanks to vaccination. The first dose is to be administered between ages of 12 and 15 months and the second between ages 4 and 6 years. Two children with measles recently traveled from Washington to Hawaii.
The measles vaccine is given as part of the combination MMR (measles, mumps, rubella) injection.
Doctors say the county has become an anti-vaxxer "hotspot" and that the only way to curb the crisis is to ban non-medical exemptions completely.
"We make a lot of decisions in our life around parenting; unfortunately, this is one that not only impacts the decision you have made for your child but also impacts other children and persons around them", Sammons added.
Those infected with measles can spread the virus four days before and four days after the rash appears.
Measles is highly infectious and spreads through the air by coughing and sneezing.
US public health officials have been worrying about recent measles outbreak in the northwest of the country, citing the low vaccination rate in the region.