As the number of confirmed measles cases in Southwest Washington and Oregon grew to 36 cases, health authorities said Monday that their biggest concern is low vaccination rates in schools and the possibility that the crisis could stretch out for months.

The threat also spread in the past few days; Deschutes County officials say someone visiting Bend on Jan. 19 and 20 may have brought measles with them. Possible exposure sites include the Mountain Air indoor trampoline park on Jan. 19 and the Juniper Swim & Fitness Center on Jan. 20.

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Dr. Paul Cieslak, a public health physician with the Oregon Health Authority, thinks the current outbreak could last two or three generations of cases.

“If you put a case of measles into a highly unvaccinated population, it can spread like wildfire,” he said.

Vaccination rates in Oregon and Southwest Washington, where measles first broke out, are comparatively low. Only 21 percent of the children at the Slavic Christian Academy in southeast Portland, for example, have all their required vaccinations.

January 2019 Measles Exposures

Measles exposure locations in Portland and SW Washington. Most recent data available here.

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Source:https://www.clark.wa.gov/public-health/measles-investigation

“We already send the letters to the parents," said principal Andrey Dolbinin. "If they’re going to have some symptoms, or something like that, they’re supposed to stay at home. At least like three weeks.”

He says some of his parents don’t vaccinate for religious reasons, because they’re worried about side effects and because they’re not convinced vaccinations are effective.

Over the last few years, flu vaccination effectiveness rate has hovered around 40 percent, which may lead to confusion about other vaccines. The measles vaccine is 98 percent effective.

So far, Clark County has reported 35 confirmed cases of measles and 11 suspected cases. There is one case so far in Multnomah County, one in King County, Washington, and now a suspected case in Deschutes County. Health officials expect the number of cases to continue to rise.

The Oregon Health Authority has added a measles explanation section to its 211 telephone hotline. And health authorities have continued to expand the list of possible exposure sites. It now includes OMSI, the Fred Meyer in Wood Village and Costco in Northeast Portland.

Complete lists of exposure sites are available on the Multnomah County and Clark County health department websites.

Cieslak said the incubation period for measles lasts about two weeks.

“Two weeks after the exposure you might see some cases, and those people who got sick are exposing other people. And then you see another generation of cases," he said. "But because the vast majority of us are immune to measles, we tend to not see more than a couple of generations of cases.”