SAN FRANCISCO (CBS SF) — Health officials Friday evening announced that they have confirmed a third case of measles in San Mateo County, bringing the total new cases announced in the Bay Area Friday to three.

The announcement follows the news that two unvaccinated siblings have contracted the first cases of measles in Marin County since 2001.

The Marin County children were exposed outside the county as part of the Disneyland Resort outbreak and were not in contact with any children at their school at the time they could have transmitted the disease, county Public Health Officer Dr. Matt Willis said.

As of Wednesday, the unvaccinated children at the siblings’ school have not been asked to stay home because of measles, the Marin County Department of Health and Human Services said.

“If there were any evidence of a school-based exposures, we immediately would put our exposure plan into place and mandate unvaccinated students to stay home from school for the recommended period,” Willis said.

California law authorizes a local health department to exclude children unvaccinated for measles from that school for the maximum incubation period of 21 days.

The previous two San Mateo County cases were not connected to the Disneyland outbreak, according to county health system spokeswoman Robyn Thaw. Thaw said she did not yet know the source of the newest case.

Measles is a respiratory disease that is transmitted through the air. It spreads through coughing and sneezing and often begins with a fever, runny nose, red eyes and sore throat followed by a rash that spreads over the body.

There were 91 cases of measles in California as of Friday, 58 of which are linked to exposure at the Disneyland Resort, according to the California Department of Public Health. However, those figures do not include the newest San Mateo County case.

In addition to the Marin County and San Mateo County cases there are six cases in Alameda County and two in Santa Clara County. The largest majority of cases have been in Southern California, closer to the center of the Disneyland outbreak.

The measles outbreak has prompted criticism of parents who choose not to vaccinate their children and those who receive exemptions from requirements that school children be vaccinated. Some parents fear the vaccine is linked to autism, but a study that purportedly bolstered the vaccine-autism link has been widely debunked.

Marin’s exemption rate is 6.5 percent, a drop of 18 percent in the past two years, the Marin County Public Health Department said.

“We hope that increasing numbers of parents will choose to protect their children and their community from preventable illnesses,” Willis said.

“Stopping the spread of measles and other illnesses requires a community-side effort. We call on all families, individuals and communities to care for their selves and others by getting immunized,” Willis said.

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