The California Department of Public Health confirmed Friday that there are now 91 cases in the state, 58 of which can be linked to visitors or employees at Disneyland or those who came in contact with them during the holidays.
The two confirmed measles patients in Marin County were both unvaccinated, officials said, and parents have been alerted that children without proof of immunity will be ordered to stay away from school for 21 days if a case occurs on campus.
Cases connected to the California-centered outbreak have also been confirmed in Arizona (five), Utah (three), Washington state (two), Michigan (one), Oregon (one), Colorado (one), Nebraska (one) and Mexico (two).
The measles outbreak has been expanding beyond those who visited Disneyland in December and January and now is affecting people in the broader community.
Ten counties in California have confirmed measles cases: Alameda, Los Angeles, Marin, Orange, Riverside, San Bernardino, San Diego, San Mateo, Santa Clara and Ventura.
Orange County has 27 confirmed cases. Los Angeles County follows with 21 cases, San Diego County with 13 and Ventura with 7.
The California patients range in age from 7 months to 70 years. Of the cases in California, about 1 in 4 have had to be hospitalized, officials said.
Across the country, health officials have painstakingly traced the steps of measles patients, tried to identify anyone who came in contact with them, and quarantined those at greatest risk of getting the highly contagious disease to keep the virus from spreading.
By keeping unvaccinated people at home before they become contagious, "we're protecting them from spreading it to others," Los Angeles County interim health officer Dr. Jeffrey Gunzenhauser said this week.
Those who suspect that they have the measles are urged to first call their healthcare provider before going to a clinic, enabling caregivers to make special preparations so patients don't risk infecting others in the waiting room.
In San Diego County, officials this month immediately shut down and disinfected an urgent care clinic after six measles patients arrived. About 160 people in contact with the patients were interviewed, and 20 were put under quarantine until they could prove they had immunity.
Symptoms of measles include fever as high as 105, cough, runny nose, redness of eyes and a rash that begins at the head and spreads to the rest of the body. It can lead to inflammation of the brain, pneumonia and death.
Officials can take steps to protect unvaccinated people if their exposure to the measles virus is known. If caught within three days of exposure, a measles vaccine can provide protection from illness. Within six days of exposure, getting a substance called immunoglobulin — concentrated antibodies extracted from donated blood that boost the immune system — can also protect the patient, experts said.
Federal recommendations call for the first dose of measles vaccination, known as MMR, to be given at 12 to 15 months of age, with a second between ages 4 and 6. California law requires two doses of the measles vaccination before kindergartners can enroll, but parents may obtain exemptions for the vaccines if they say the inoculations conflict with their personal beliefs.
Health officials said infants too young to be immunized are particularly at risk and should avoid large crowds where international travelers are concentrated, such as theme parks and airports.
At least six of the California cases occurred in infants too young to be immunized, state officials said.
In Alameda County, officials this week ordered 30 babies to be placed under home isolation after possible exposure to the highly contagious disease. The babies are not infected, health officials said, but had some contact or connection to the Disneyland-related measles patients in the county.