Amber Gorrow holds her son Leon, 8 weeks, at their home in Vancouver, Washington, on Wednesday, Feb. 6, 2019. When the measles outbreak started in Vancouver last month, Gorrow decided to stay at home with her son as much as possible so he wouldn’t be exposed before he is old enough to get the vaccine. MUST CREDIT: Photo for The Washington Post by Alisha Jucevic.

Measles cases are on the rise statewide this year, with 15 new cases reported just last week. And those numbers reveal a disturbing new trend: About three-quarters of this year’s 38 reported cases occurred in adults who had never received vaccinations or had partial vaccinations.

California public health officials said Thursday that the San Francisco Bay Area has reported 10 confirmed cases of measles this year, most of them linked to unvaccinated adults exposed through international travel. Four were in Santa Clara County, four in San Mateo County, one in San Francisco County and one in Santa Cruz County.

“If you are traveling to a part of the world with elevated measles cases, you should know if you are vaccinated,” said Dr. Karen Smith, Director of the California Department of Public Health.

This year’s pattern of disease is different than in prior years, when the majority of cases were seen in unvaccinated children.

Health officials worry that infected adult travelers could transmit it to children, who could spread the highly contagious virus through daycare facilities and schools. UNICEF reported Thursday that “nearly 170 million children worldwide, including more than 2.5 million in the United States and half a million in Britain, missed out on the first dose of the measles vaccine during the past eight years,” according to a story in the New York Times.

The measles cases were brought to California from people who visited the Philippines, Thailand, India, Ukraine and Cambodia, where very large measles outbreaks are occurring, Smith said.

“We have an adult population that is unvaccinated in California,” she said. “When that pool of unvaccinated adults travels to places where there there is an outbreak … it is imported into California.”

Many adults attended school before vaccines were mandatory, she explained. Others moved here from parts of the world where vaccines are less available.

Measles, a preventable disease, once had been effectively eliminated from our country. Now it is resurging.

New cases in the United States have exceeded the highest number on record in a single year since the disease was thought to have been eliminated in 2000, the U.S. Centers for Disease Control reported on Wednesday.

Nationwide, 695 cases of the illness have been reported in 22 states this year, according to the CDC. That’s more than the 667 cases reported in all of 2014, another dangerous year. The largest outbreak is in New York City, centered in a predominantly Orthodox Jewish community in Brooklyn, with 334 cases there this year, according to the New York Times. Authorities link it to travel to an annual Hasidic pilgrimage from Israel to Ukraine, nations with major outbreaks.

In a typical year, California experiences between 10 and 25 cases. There were only 22 cases all of last year. The last major outbreak was in 2015, with 125 cases.

There was a major uptick last week, with 15 new cases reported statewide, said Smith. That compares with 11 cases at this time in 2018. Of the 38 2019 cases, 14 were in international travelers, 22 were spread from travelers to people in California, and two are of unknown origin.

In addition to the 10 Bay Area cases, other affected California counties include Los Angeles with six cases and Placer and Sacramento with three cases each. There have been 16 total cases in Butte, Shasta, Tehama and Calaveras counties.

On Thursday, the Los Angeles County public health department issued a quarantine for the UCLA and Cal State, Los Angeles campuses because of possible exposure to a student who was infected, according to a news report by ABC7. The quarantine affected more than 100 people who will be tested for immunity to the disease, the station reported.

While most of this year’s cases did not trigger large outbreaks of the disease, there were four incidents, including one in the Bay Area, where one sick person spread it to more than three other people. That Bay Area outbreak is now over.

Health officials confirmed in March that at least three Bay Area residents in Santa Clara, San Francisco and Santa Cruz counties contracted measles, two of them from the other person in the same airplane flight. In February, a Santa Cruz County resident with measles was on an international flight that landed at San Francisco International Airport, according to the Santa Clara County Public Health Department. It’s unclear whether that person knew he or she had measles at the time. Since then, two other passengers on that flight caught the disease — one from San Francisco and the other from Santa Clara County.

About 65 percent of infected Californians had not been vaccinated, said Dr. Gil F. Chavez, deputy director of the state’s Center for Infectious Diseases. About 10 percent had just one dose of the two-dose vaccine. The rest had been vaccinated but were not fully protected, he said.

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Exceedingly contagious, the measles virus can linger in the air up to two hours after an infected person — who may not yet feel sick — has left a room.

“That is why we pay so much attention to vaccination,” said Smith. “It is the single most powerful tool to protect public health.”

Staff writer Annie Sciacca contributed to this story.

Should I get vaccinated?

If you were born before 1957, you may have experienced measles and are now protected. But if you’re younger than that or don’t know whether you’re immune or not, you should try to find your vaccination records or documentation of measles immunity.

If you do not have written documentation of measles immunity, you should get vaccinated with measles-mumps-rubella (MMR) vaccine.There is no harm in getting another dose of MMR vaccine if you’ve had either the vaccine or any of the three diseases covered by the vaccine.

Another option is to have a doctor test your blood to determine whether you’re immune. But this option is likely to cost more and will take two doctor’s visits.

Lisa M. Krieger is a science writer at The Mercury News, covering research, scientific policy and environmental news from Stanford University, the University of California, NASA-Ames, U.S. Geological Survey and other Bay Area-based research facilities. Lisa also contributes to the Videography team. She graduated from Duke University with a degree in biology. Outside of work, she enjoys photography, backpacking, swimming and bird-watching.

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