Since December, 134 confirmed measles cases have been reported by California residents. The latest was on March 2, according to the California Department of Public Health's weekly update released last week.
Officials said 40 of those cases were confirmed to be Disneyland visitors and another 30 were people who came in close contact with a patient in their own home.
Nearly a dozen became infected in community areas like hospital emergency rooms. Experts don't know where another 50 patients became infected but confirmed they were stricken with the same strain of the virus connected to the Disneyland outbreak.
The source of the Disneyland outbreak was a patient who was probably exposed to the measles overseas and then visited the Anaheim amusement park while contagious, according to the federal Centers for Disease Control and Prevention.
This particular strain of measles is identical to one that spread through the Philippines last year, where it sickened about 58,000 people and killed 110. No deaths have been traced to the Disneyland outbreak.
Three California state legislators have introduced a bill that would make it more difficult for parents to opt out of having their children vaccinated by claiming a personal belief exemption.
The bill, SB 277, would require children to be vaccinated against measles and other infectious diseases before enrolling in California schools. One of the sponsors of the bill is Assemblyman
Under the legislation, parents could still receive an exemption from vaccination requirements for medical reasons, such as an immune-system problem. It also allows exemptions for children who are home-schooled.
More than 13,500 kindergartners in California have waivers based on their parents' personal beliefs.
Staff writers Rosanna Xia and Emily Foxhall contributed to this report.