There are now 51 confirmed cases of the highly contagious virus across California, three other states and Mexico, and the Orange County Health Care Agency said the reports of new cases "indicate the measles outbreak will continue to spread."
Health officials had hoped to contain the outbreak to Disneyland visitors who were at the park between Dec. 17 and 20, when the virus spread from perhaps a single infected person or an ill family. But Orange County is now reporting six new cases of measles involving people who did not visit the Anaheim attraction during that period. State officials said there were two more such cases in Ventura County and one in Alameda County.
Orange County Health Officer Eric Handler warned that students who have not been vaccinated for measles may be excluded from attending school or day-care to prevent the further spread of the disease. A person who may have been contagious with measles was at Huntington Beach High School on Jan. 7-8.
There are now 16 confirmed measles cases in Orange County, with San Diego County, where there are 10 confirmed cases, the second-hardest hit. Also affected are the counties of Los Angeles (8), Alameda (4), Ventura (3), Riverside (2), and San Bernardino (2), for a total of 45 measles cases in California.
The six other confirmed cases are residents of Colorado (1), Utah (2), Washington state (2), and Mexico (1), a 22-month-old unvaccinated girl who visited Disneyland between Dec. 16 and 18.
Officials say that many who have become ill were not vaccinated for measles. In the San Diego County cases alone, nine out of the 10 who fell ill did not get the measles vaccine.
The measles vaccine was introduced in the U.S. in 1963, and for more than a decade the disease has been considered eliminated from the Western Hemisphere, meaning domestic transmission of the disease does not occur here. Measles has still been a problem when brought in by travelers from Western Europe and Southeast Asia, but the disease has been eventually extinguished by a ring of vaccinated people.
But health officials have long expressed fears that progress against measles was threatened by a growing anti-vaccination movement in the United States, based on parents' fears that the vaccine causes autism -- a theory that has been thoroughly discredited by numerous scientific studies.
"The greatest threat to the U.S. vaccination program may now come from parents' hesitancy to vaccinate their children," Dr. Mark Grabowsky, a health official with the United Nations, wrote last year in the Journal of the American Medical Assn.-Pediatrics. "Although this so-called vaccine hesistancy has not become as widespread in the United States as it appears to have become in Europe, it is increasing."
"Many measles outbreaks can be traced to people refusing to be vaccinated; a recent large measles outbreak was attributable to a church advocating the refusal of measles vaccination."
A Times analysis published last September reported that the rise in vaccine exemptions among kindergartners because of parents' personal beliefs was most prominent in wealthy coastal and mountain communities, such as southern Orange County and the Santa Monica and Malibu areas.
Health officials are urging people suspected of having of the measles to first call their health provider before going to a clinic, enabling caregivers to make special preparations so patients don't risk infecting others. An urgent care clinic in the San Diego suburb of La Mesa was forced to shut down on Wednesday when five people arrived with the rash.
Officials said that the best prevention is inoculation. In California, two doses are required for children entering kindergarten, but parents can obtain an exemption for a child by submitting a "personal belief exemption."
Measles is one of the most contagious diseases known and can be especially severe in babies, toddlers and pregnant women, as well as other adults. Especially vulnerable are infants less than 12 months of age, who are too young to get their first dose of the vaccine, known as MMR for measles,
For every 1,000 children who get the measles, one or two will die from it, and one will get brain swelling so severe it can lead to convulsions and leave the child deaf or mentally impaired, according to the U.S. Centers for Disease Control and Prevention.
During a 1988-91 outbreak, there were about 75 deaths due to measles in California alone, mostly children under 5.
Measles spreads through respiratory droplets that become airborne during a cough or sneeze. "You can catch measles just by being in a room where a person with measles has been — even if the person is gone," according to the CDC.
A person with measles is infectious as soon as coughing and sneezing begins but before the rash appears — first on the head, then spreading to the rest of the body. Patients can be contagious for four days before the rash appears and four days after. Other symptoms include fever, red eyes and runny nose.