The 2015 measles outbreak already has spread to 84 people, more than health officials typically see in an entire year, the Centers for Disease Control and Prevention reported Thursday.

Most of the cases are traceable to an outbreak at Disneyland and another theme park in Southern California that began in late December and now has spread to six other states, including Utah, Washington, Oregon and Colorado. In all, measles has reached 14 states, according to Anne Schuchat, director of the CDC’s National Center for Immunization and Respiratory Diseases.

The outbreak has generated sometimes fierce criticism of people who, for personal reasons or because they mistrust the vaccine, choose not to have their children immunized and prompted at least two school systems in California to ban unvaccinated students from school.

Schuchat held a briefing for reporters and others Thursday in an attempt to “prevent measles from getting a foothold and becoming endemic again.” She urged parents to get the measles, mumps, rubella vaccine for their children and themselves, noting that the two-dose regimen is 97  percent effective and has been proven safe despite unproven concerns that it can lead to autism.

She also said children should get their first dose at age 1, when it is recommended. Some parents have been delaying the age of first immunization.


“MMR vaccine [is] very safe, very effective, really necessary,” Schuchat said. “And the 12-month routine first dose, we really strongly recommend.

Measles, which is caused by a virus, is highly contagious. The respiratory illness is airborne, spread from person to person by coughing and sneezing. It is so infectious that an  unvaccinated person can contract it by inhaling the virus hours after a person with the disease has left a room.

It can lead to potentially serious complications, including pneumonia, brain damage and deafness. About 15 percent of the people infected in the current outbreak required hospitalization, Schuchat said.

The United States declared measles eliminated in 2000, but it has been resurgent in recent years, fueled by huge epidemics in other countries that were imported into the United States by travelers and spread mostly among unvaccinated people. Last year, for example,  when the measles toll in the Philippines reached 50,000 cases, the United States saw 644, including a cluster in Ohio among unvaccinated people in the Amish community.