As more parents forgo measles vaccinations for their children, the number of Californians contracting the highly contagious disease has reached a 10-year high, outpacing every other state in the nation.
As of Monday, there were 28 reported cases of measles so far in 2011 — the largest statewide figure reported, according to state and federal health officials. That is the highest incidence since 2001, when 40 people in California reported having measles. There were nine cases in all of 2009 and 27 cases in 2010.
Of the cases reported this year, 22 of the 28 either were unvaccinated or very likely to lack the vaccine, according to the California Department of Public Health. More than half had recently traveled internationally, including to Asia and Europe, which have seen a drop in immunizations and widespread outbreaks.
Measles, transmitted through coughing and sneezing, can cause ear infections, pneumonia, diarrhea, brain injuries and death. Cases can quickly spread in schools and communities, especially in areas with a high concentration of unvaccinated children, officials said.
“We are quite concerned in California,” said Gil Chavez, deputy director of the Center for Infectious Diseases at the state Department of Public Health. “Even one single case that is acquired overseas can expose a lot of individuals.”
Cases are also on the rise around the nation. In 2011, 211 people were diagnosed with measles — the highest number in 15 years, according to the Centers for Disease Control and Prevention. Many contracted it abroad, and about 85% were unvaccinated or had undocumented vaccination status.
The disease was eliminated in the United States in 2000. But those traveling outside the country often don’t realize the danger of exposure, said Preeta Kutty, a medical epidemiologist at the CDC.
“We are working very hard to make sure the disease does not spread,” Kutty said. Those going abroad “need to be aware of the disease and be up to date with their vaccine.”
The two-dose vaccine, introduced in 1963, is available for free for those who cannot afford it.
The number of unvaccinated children has grown over the last decade, partly because of parent fears of a link between the shots and autism, a theory repeatedly disproved in scientific literature. To opt out of the vaccine, parents simply fill out a form.
Seven of this year’s measles cases were in Los Angeles County, four in San Diego County and three in Mendocino and Santa Clara counties, with the remainder scattered over several other counties, according to the state.
The rising number of cases should be a “wake-up call to make sure we are keeping that vaccine guard up,” said Robert Kim-Farley, director of communicable disease control and prevention for Los Angeles County. County health officials are working to counter myths about measles vaccinations and autism, he said.
“In the developing world, parents clamor for these vaccines,” he said. “It’s only in the developed world that we have seen this complacency of vaccination set in.”
Outbreaks can occur when just 5% to 10% of a population are not vaccinated, according to the CDC. In California last year, 11,500 kindergartners started school with vaccine exemptions, up from 8,300 in 2007. In Los Angeles Unified School District, 30% of kindergartners at Topanga Elementary Charter School began school without shots, as did 43% at Ocean Charter School.
In some schools around the state, the rates of unvaccinated children are even higher. For example, 84% of kindergartners at Yuba River Charter School in Nevada City and 63% of kindergartners at San Geronimo Valley Elementary School in Marin County started school without getting their shots.
Chavez said there was a risky trend of families skipping the vaccine at certain schools. “When you have a kid that is infected and attends school where you have a large number of unimmunized children, that can provide a very dangerous mix,” he said.