By Kathleen DohenyWebMD Health News

Reviewed by Michael W. Smith, MD

Jan. 20, 2015 — At least 42 people have caught measles in an outbreak linked to Disneyland and Disney California Adventure Park over the Christmas holidays, health officials say.

The number includes 36 people in California and six from other states and Mexico, according to the California Department of Public Health.

While the contagious period is over, concerns about measles and future outbreaks remain.

Here, experts address what 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?

Diarrhea and ear infections can happen, according to the CDC. The infections can lead to hearing loss. Pneumonia and swelling of the brain are other potential 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.

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.

SOURCES: Aaron Glatt, MD, infectious disease specialist and spokesperson, Infectious Diseases Society of America. Centers for Disease Control and Prevention: “Measles.” Press release, California Department of Public Health.

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