Since Jan. 1, there have been 15 cases of measles in California, compared to just two this time last year, according to health officials.
Not confined to one area, the cases are reported throughout the state, says Dr. Ron Chapman, state health officer and director of the California Department of Public Health in Sacramento.
Measles was irradicated in the U.S. in 2000, due to the prevalence of child Measles, Mumps, and Rubella (MMR) vaccinations. Immunization protects people from contracting the measles 99 percent of the time.
"Immunization is the best defense against measles, with 99 percent of persons developing immunity after two doses," Chapman said in a statement. "With an outbreak in the Philippines and measles transmission ongoing in many parts of the world outside of North and South America, we can expect to see more imported cases of this vaccine-preventable disease."
California state epidemiologist Dr. Gil Chavez says for each case local health officials must track dozens of those who may have been exposed and infected.
"There's a tremendous burden to the counties and society," Chavez said.
"A myth persists among many parents that the measles vaccine is dangerous," he added. "These illnesses continue to make a comeback because we have people who refuse to be vaccinated."
The 15 cases were reported in six counties, including five in Los Angeles County, three each in Orange and Riverside counties, and four combined in Alameda, Contra Costa and San Mateo counties.
Chapman said among the 15 patients, three traveled to the Philippines, where a large outbreak is occurring. Two travelled to India, where measles is endemic.
Chavez says anyone who is unsure of their vaccination history should be vaccinated before traveling.
Two of the individuals had been vaccinated against the measles, but the rest had not. Seven of the patients say their parents opted for them to skip childhood immunizations through the state’s personal belief exemption law.
Dr. Kathleen Harriman, of the public health department's immunization branch, told the Los Angeles Times that fewer than three percent of California school children use this exemption.