Updated April 25, 12:34 p.m.
There have been 39 cases of measles reported in California so far in 2019, according to county departments of public health throughout the state.
On Wednesday Sacramento County reported three cases of measles in a family that had recently traveled internationally, the first reported cases this year in the county.
Butte County has the highest number of cases in the state currently, with 11 reported so far. Placer, Shasta, Los Angeles, San Mateo, San Francisco, Santa Cruz, Tehama, Calaveras and Santa Clara counties have also reported cases.
The rash of one of the patients reported by the California Department of Public Health in Los Angeles County appeared in late December of 2018, but the patient is being included in California's 2019 case counts due to reporting methods for the Centers for Disease Control and Prevention.
Many of the cases reported have been in counties with relatively small populations. Butte County has nearly 5 cases per 100,000 residents, while Shasta and Calaveras counties have about 2 cases per 100,000, according to 2017 population counts.
Measles spreads easily by air, and those who develop an illness with a high fever, cough, runny nose or red eyes, with or without a rash, should contact a doctor, according to the Sacramento County Department of Public Health. Anyone diagnosed with measles should stay home until a doctor clears them.
Sacramento County public health officials are encouraging anyone 12 months or older to get immunized against measles with two doses of the measles, mumps and rubella (MMR) vaccine.
“One dose of the measles-mumps-rubella vaccine provides up to 95 percent protection,” Sacramento County Public Health Officer Dr. Olivia Kasirye said in a news release. “The second dose can be given as soon as a month after the first dose, which boosts protection to nearly 100 percent.”
More than three quarters of Californians who’ve contracted measles this year were unvaccinated or undervaccinated, said Dr. Gil Chavez, California’s state epidemiologist. He noted that four of the current measles led to further measles transmission, while the rest were standalone cases.
State health officer Dr. Karen Smith said the disease is more likely to spread in communities where large numbers of children are unvaccinated. In some counties, more than half of children do not have their required shots.
“One of the reasons that most of the travelers who’ve returned to California with measles have not spread it to others is because we have high vaccination rates overall,” Smith said. “A major part of that is ensuring children entering school are vaccinated.”
Some lawmakers are currently trying to strengthen vaccine requirements in California schools by restricting who can get medical exemptions.
As of Tuesday, 680 cases of measles have been reported in the U.S. This is the highest level of measles infections in 25 years, and the resurgence is largely attributed to misinformation turning parents against vaccines, according to the Associated Press.
This story is still developing. We will be updating this page as more measles cases are reported throughout the state.