People who are unvaccinated need to know that the epidemiology of vaccine-preventable diseases and the risk of vaccine preventable diseases is changing — it's going up," said Karen Holbrook, the county's interim public health officer.
"Even though we don't have any cases in Sonoma County, right now I'm concerned," she said.
In a teleconference with reporters Friday, Kathleen Harriman of the California Department of Public Health said that fewer than 3 percent of kids statewide have not been vaccinated by the time they get to kindergarten. In these cases, the parents have received personal belief exemptions.
Holbrook said in Sonoma County, 6.3 percent of parents request such an exemption. But in the west county, nonvaccination rates are much higher, she said.
In Sebastopol Union and Twin Hills school districts, 40 percent or more of parents request personal belief exemptions, Holbrook said. A new law that took effect Jan. 1 now requires parents to obtain a signed statement from a heath care professional that shows they received medical information about the benefits and risks of vaccines.
"We look forward to the new law that will be in place for the next school year," said Linda Irving, superintendent of Twin Hills. "It will give parents the opportunity to discuss vaccinations more in-depth with regard to personal belief exemptions."
There have been no measles-related deaths, state health officials said Friday. The actual number of measles cases may be higher because there is a lag between the time counties document cases and the time the state reports them.
During the Friday teleconference, state epidemiologist Dr. Gil Chavez said that a significant number of the 15 measles cases involved people who traveled — or were exposed to those who traveled — to other countries with high rates of measles infections.
Three traveled to the Philippines, two to India and two others were exposed to international travelers, Chavez said. He urged Californians who are traveling outside of North and South America to "make sure you're the fully vaccinated." Places such as the Philippines, India and some countries in Europe are especially troublesome, he said.
Health officials said the current outbreak of measles in the Philippines may have been exacerbated by the devastating typhoon that hit the region in November.
Chavez urged parents to make sure their children are vaccinated against the measles virus, noting that seven of the 15 cases involved parents who obtained personal belief exemptions. Five of these cases involved underage children and two were young adults.
State officials said that two of the 15 statewide measles cases involved people who were vaccinated. In general, they said, about one percent of those who receive the measles vaccine "remain susceptible" to the virus.
Holbrook said measles, a viral disease that before the 1960s affected nearly everyone in the United States, was declared eradicated in this country by 2000. Nationally, a low of 37 cases were reported in 2004.
"Since then we've had an increase in cases, imported and contacts to those that bring it into the country," she said, adding that there is also an "upward trend" in cases both in underdeveloped and developed nations.
She said measles is now endemic in many parts of the world including, England, France, Spain and Israel, where many people are choosing not to get vaccinated. Measles spreads quickly because it is a highly contagious disease.