Vaccination status is known for 34 of the California patients. State officials say that 28 were not vaccinated at all, one was partially vaccinated and five were fully vaccinated. (Six of the unvaccinated were babies, too young to be vaccinated.)
"Measles is not a trivial illness," said state epidemiologist Dr. Gil Chavez. "It can be very serious with devastating consequences." Those consequences include pneumonia, encephalitis, and even death. Before the measles vaccine was introduced in 1963, 500 people a year died of the disease nationwide. In the current outbreak, 25 percent of people with measles have been hospitalized.
In 1989-1991, a measles epidemic swept California and other places around the U.S. There were 17,000 cases in California, and 70 people died. In Philadelphia, nine children died in just three months. "The city was in a panic," Dr. Paul Offit of Children's Hospital of Philadelphia told me, "I saw children die of measles dehydration … measles encephalitis, measles can kill you."
By county, the case numbers are as follows:
- Alameda 5
- L.A. County 12
- Orange 20
- Riverside 4
- San Bernardino 3
- San Diego 10
- San Mateo 1
- Santa Clara 1
- Ventura 1
Chavez stressed that Disneyland was a safe place to go -- as long as you are vaccinated. "If you are not vaccinated, stay away from Disneyland," he said. The problem is not with Disneyland itself, but any place where large numbers -- including people from foreign countries -- congregate. Chavez described Disneyland staff as being helpful and "quite concerned" about the outbreak. Five Disneyland staff members are among the 59 cases.
Measles was declared eliminated from the United States in 2000, but can still be reintroduced if someone from another country is infected and travels to the U.S. -- or an unvaccinated person in the U.S. travels abroad and brings the illness back.
Measles is a highly infectious, airborne illness. It starts off with fever as high as 105 degrees, followed by symptoms that resemble a cold -- a cough and runny nose. The hallmark of measles is a red rash that appears first on the face and upper neck, then spreads to the rest of the body. If someone with measles coughs or sneezes, droplets of virus can live on surfaces up to two hours.
On the press call with reporters Wednesday afternoon, Kathleen Harriman with the California Department of Public Health described published case reports of a person with measles at a basketball game -- and people across the court became infected, "because the virus can float and hang out in the air for a long, long time," she said.
Dr. Chavez urged everyone who was not vaccinated to get immunized. The first dose of vaccine, called MMR as it protects against measles, mumps and rubella, is given at 12-15 months of age. The second dose is given at age 4-6. Most people who get the vaccine do not experience side effects, but the most common ones are fever and a mild rash.
If you were born before 1957, you are presumed to be immune to measles, because the disease was so widespread before the introduction of the vaccine. For years, only one dose was recommended, it protects 95 percent of people. The second dose was recommended starting in 1991. If you don't know your vaccine status, Harriman said you can safely get the MMR vaccine -- if it's an extra dose, it won't hurt you, she said.
Related: Look Up Your School's Vaccine Opt-Out Rate Online
Local health officers in counties affected are busy tracing those who infected patients have been in contact with. Dr. Erica Pan, deputy health officer of Alameda County, says the county has shifted resources from ebola preparedness to contact tracing for measles. Last year there were four cases of measles in Alameda County, she said, "but we had 400 contacts to investigate."
The measles outbreak comes after years of increase of parents refusing vaccines for their children. From the 2007-2008 to 2013-2014 school years, the rate of kindergarten parents choosing the "personal belief exemption" to refuse vaccines doubled. While the statewide rate of personal belief exemptions reached 3.15 percent, geographic clusters had significantly higher opt-out rates.
But that steady increase in vaccine refusals was halted with the current school year -- likely due to a new state law. This school year is the first when parents who chose to opt out needed to meet first with a health care provider to discuss vaccines and vaccine preventable illnesses. The goal is to dispel misinformation and fear of vaccines. The opt-out rate dropped from 3.15 to 2.54 percent, nearly a 20 percent decrease.