Editor’s note: This story was updated Jan. 29, 2015, with case numbers and news of Arizona reportedly monitoring 1,000 people.
Jan. 20, 2015 -- The number of people with measles in California and other Western states is growing, health officials say.
Most of the cases are linked to Disneyland and Disney California Adventure Park, and five Disney employees caught the disease. Initial exposures at the parks happened in December, according to the California Department of Public Health, but other people with measles “visited Disney parks while infectious in January.”
As of Jan. 28, at least 95 people -- mainly in California but also in a handful of other states and Mexico -- have measles, according to the California Department of Public Health.
"We anticipate we will see additional cases,” said Gil Chavez, MD, MPH, deputy director of the Center for Infectious Diseases at the department, in a briefing Jan. 21.
Already, the number of confirmed cases in California is about the same as the state saw for all of 2014, he said.
Officials said Jan. 21 they know whether or not 34 people in California got vaccinated. Of those, 28 were not vaccinated.
But five people received at least the recommended two vaccine doses. One received a single dose. (The vaccine is thought to be 95% effective after one dose, and more so after two doses.)
Other affected states include Arizona, Utah, Washington, Colorado, Oregon, and Nebraska, along with Mexico.
Arizona, which has seen at least five cases of measles as of Jan. 28, was keeping tabs on 1,000 people, including nearly 200 children, who could have been exposed at a Phoenix-area medical center, according to the Arizona Department of Health Services. Those who haven't been vaccinated are reportedly being asked to stay home for 21 days or wear masks if they go out in public.
Here, experts address what else you need to know.
Q: How widespread is measles now?
The United States declared measles eliminated in 2000, according to the CDC. But outbreaks in recent years have been reported in Western Europe, Pakistan, Vietnam, and the Philippines. Travelers from those areas can bring the disease back to the U.S. when they visit.
U.S. measles cases in 2014 hit a record number since the 2000 declaration, according to the CDC -- 644 cases were reported in 27 states.
Q: Who brought the measles to the amusement parks?
Public health experts haven't yet found the first patient, and doing so can be "almost impossible," says Aaron Glatt, MD. He's an infectious disease specialist and spokesperson for the Infectious Diseases Society of America.
Q: How is measles spread, and does it spread easily?
"You can catch it from anyone who has measles," Glatt says. The virus lives in the nose and throat mucus of the person affected, according to the CDC. When the infected person coughs or sneezes, the virus can be spread.
The virus is capable of living for up to 2 hours on a surface or in airspace, the CDC says. When others touch an infected surface, then touch their mouth, nose, or eyes -- or, when they breathe the air with the virus -- it can be spread and an infection can happen.
Measles is highly infectious. According to CDC estimates, 90% of those who aren't immune to the measles virus and are close to an infected person will also get measles.
Q: What are the first symptoms and how quickly do they usually show up?
Typically, people infected have a fever, cough, runny nose, and red eyes. Within a few days, the hallmark red rash usually appears, usually first on the face. It then can spread to the rest of the body.
According to the CDC, those infected can spread measles from 4 days before to 4 days after the rash first appears.
Q: What are the possible complications?
About 1 or 2 of every 1,000 children with measles will die of it, the CDC estimates.
Q: How do you prevent measles?
"There's only one way to prevent it," Glatt says. "Vaccinate, vaccinate, vaccinate." He blames the anti-vaccine movement in the U.S., with parents refusing to vaccinate their children, for current outbreaks. "You really should not be allowing your children to go to school if they are not vaccinated," he says.
Two doses of measles-containing vaccine, or MMR, provides more than 99% effectiveness in preventing measles, according to the California Department of Public Health. It also protects against mumps and rubella, or German measles.
The first dose is usually given at 12 months old, and a second before kindergarten.
The American Academy of Pediatrics is urging parents to vaccinate their children against measles.
“A family vacation to an amusement park -- or a trip to the grocery store, a football game, or school -- should not result in children becoming sickened by an almost 100% preventable disease,” says Errol Alden, MD, the academy’s executive director, in a statement.
Q: If you think you’ve been exposed to measles and haven't been vaccinated, can you still get the vaccine?
Yes, according to Kathleen Harriman, PhD, MPH, RN. She's the chief of the vaccine preventable disease epidemiology section at the California Department of Public Health.
“MMR (measles, mumps and rubella) is one of our post-exposure vaccines, but it has to be given within 72 hours of exposure to be effective,” she says. “We can also give immunoglobulin. It can be given up to six days after exposure.”
Those measures may provide some protection or change the course of the disease, according to the CDC.
Q: What should you do if you think you notice the first symptoms?
Contact your doctor or your child's doctor right away, Glatt says. Tell them what you see so they can take proper precautions.