BEND, Ore. — The vaccination rate for measles in Oregon has fallen low enough to cause a state public health official to worry about the spread of the highly infectious disease.
A Lane County man is among more than 100 people nationwide who got measles in an outbreak that apparently began at Disneyland.
He visited in early January, and officials like to wait four weeks to say for sure that nobody else has caught it.
The vaccination rate among toddlers has been falling in Oregon for 15 years as an increasing percentage of parents claim either religious or philosophical exemptions from state vaccination requirements.
In Oregon, 90.9 percent of children between 19 months and 35 months have been vaccinated against measles, mumps and rubella, according to the U.S. Centers for Disease Control and Prevention.
This falls well below the target of 94 percent, the point at which there’s a lack of susceptible hosts, so what’s known as herd immunity begins to keep the disease from spreading, said Dr. Paul Cieslak, medical director for Oregon’s immunization program.
Measles cases in Oregon generally are imports, such as from Asia and Europe, where the disease is more prevalent, Cieslak told The Bulletin newspaper of Bend.
His view until recently was that the vaccination rate appears to be high enough to stop the spread of the disease. But now, Cieslak said, “We’re kind of on the cusp.”
He cited “chains of transmission” in California. “The problem is not so much that there was an incident in Disneyland, but that the virus seems to be spreading,” Cieslak said.
In a totally unimmunized population, a single measles case will likely result in an additional 15 infections.
Before the introduction of a measles vaccine in 1963, 3 million to 4 million Americans contracted the disease each year, according to the Centers for Disease Control and Prevention. Of those, 400 to 500 died and 48,000 were hospitalized.
Thanks largely to vaccinations, measles were considered eliminated in the United States in 2000, meaning there was an absence of continuous transmission for a 12-month period.
Oregon figures mirror a national trend of rising numbers of measles cases: 17 from 2000 to 2012, or about 1.3 a year; six in 2013; five in 2014; and the Lane County case so far this year.
“We have the potential to eradicate this disease completely. But we’re not going to achieve that unless we can convince a higher percentage to get vaccinated,” Cieslak said.
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