The number of confirmed cases of measles near Portland rose to 31 on Friday – a phenomenon that has increased with lower rates of vaccination in what is called the US "hot spot" against vaccination.
Public health officials in southwestern Washington, right across the Columbia River from Portland, Oregon, said people may have been exposed to a dangerous disease in more than three dozen locations, including the Portland International Airport, a game in Portland Trail Blazers, the location of Amazon Locker and stores such as Costco and Ikea.
Twenty-six of the confirmed patients were not vaccinated against measles, and the status of vaccination of four others who were infected is unknown. One child is hospitalized. Authorities say there are suspicions of nine additional cases.
One case was also confirmed in the King County, home of Seattle, and one was confirmed on Friday night in the County of Multimah, home to Portland.
Most of the cases are children younger than 10 years old, according to the Department of Public Health in Clark County. An adult is infected, and the rest is teenagers. Officials from Oregon did not bring the age of the infected people there.
Washington Governor Jay Insley, Democrat, declared a state of emergency for his state on Friday. Authorities in neighboring Oregon and Idaho issued warnings.
Inslee said the number of cases "creates an extreme public health risk that can quickly spread to other countries."
The measles vaccine has been part of routine childhood footage for decades, and measles have been declared eliminated in the United States in 2000.
But measles is still a major problem in other parts of the world. Travelers infected abroad can bring the virus to the country and spread it, causing periodic epidemics.
Last year, there were 17 outbreaks and about 350 measles cases in the United States.
Officials are still not sure where this phenomenon began in the Pacific Northwest. The first known patient sought medical care on December 31, but it is unclear whether other people may have been ill before and have not sought treatment. Public health services are now focused on preventing more exposure.
It could be weeks or even months before the "virus-infectious" virus that runs its course in Washington, said Dr. Alan Melnik, a medical officer in Clark County on Friday.
People who do not want to vaccinate their children underestimate the dangers of the disease, Melnik said, who had small measles as a child, before the vaccine is common.
Before the vaccine, every year from 400 to 500 people were killed by measles, 50,000 people were hospitalized, and 4,000 people developed a brain swelling that could cause deafness, he said. Between one and three cases of every 1,000 are fatal, he said.
"It's one of the most infectious viruses we have. There may be really serious complications … and it's completely prevented by an incredibly cheap and safe vaccine," Melnik said.
Clark County has already spent more than $ 100,000 trying to prevent the onset of the disease, and employees are retiring from other duties, including inspections at restaurants, he said.
"It's all in the hands of the deck. It's clear that this will cost hundreds of thousands of dollars, and it would not surprise me if we were in the seven figures when we finish here," he said. "These costs can be prevented if we all vaccinated them."
Clark County, which includes the bedroom community in Portland, Vancouver, Washington, has a vaccine rate of 78 per cent, which is well below 92 to 94 per cent needed for the so-called. "herd immunity," said Marissa Armstrong, spokeswoman for the department. Food immunity occurs when non-vaccinated individuals are protected from infection because almost all of them are vaccinated and immune to disease.
The measles vaccination rate for 2-year-olds in the County of Multimah, home to Portland, was 87 percent in 2017, according to the country's data. The measles vaccine consists of two strokes, one of the age 2, and the second usually between 4 and 6 years.
The figures for the Portland vaccination record for both shots were not immediately available.
Two doses of childhood vaccine are 97 per cent effective and provide vital immunity. One dose is effective for 93 per cent.
Both Washington and Oregon allow exemptions from vaccines for personal and philosophical reasons. Armstrong's vaccine vaccine rate for non-medical reasons was high, with 7.5 per cent, said Armstrong.
The period of incubation for measles is seven to 21 days, which means that the unvaccinated person who is exposed can go out publicly until three weeks before getting sick. Patients remain infectious four days after the development of the rash.
The virus, which is spread by coughing or sneezing, can stay in the air for up to two hours in an isolated area. Ninety percent of people who are exposed to measles who have not been vaccinated will receive this, public health officials say.
Every time an unvaccinated person exposed to measles appears in the public, "that watch starts over," Armstrong said.
Earlier this week, the authorities managed to identify several people who had been exposed but were not yet ill. Those people stayed home and later got sick, said Armstrong.
Those who may have been exposed should be alert to the early symptoms of fever and malaise, and then to a rash that begins on the head and moves down the body. Serious complications such as pneumonia and brain infections may arise from the disease in some cases.