Measles has now been confirmed in 22 Orange County (OC) residents, signaling ongoing transmission in the community and at the Disneyland Parks . Thirteen of these cases spent time at the Disneyland Parks since mid-December, 2014. In California, as of today, 59 cases of measles have been confirmed since the end of December; 42 of these had an exposure in December at Disneyland or California Adventure Park. Additional cases have been identified that were at the park while infectious in January, including within the last week. Nine of the OC cases have no Disney or other known measles exposure. Additional cases are expected in Orange County. Of the 22 Orange County cases, five are children, of whom four were not vaccinated and two were hospitalized. Although some of the confirmed cases occurred in people with a history of vaccination, their illness is generally milder and typically not as infectious. Vaccination is critical to prevent the ongoing spread of disease . Although the overall risk of getting measles in Orange County remains low, residents who have not received any measles-containing vaccine should get a dose of MMR vaccine. Two doses of measles-containing vaccine (MMR vaccine) are more than 99% effective in preventing measles. The first dose is routinely given at 12-15 months of age, with the second dose usually at age 4-6 years. The second dose may be given any time ≥28 days after the first dose. All healthcare workers (HCW) should have two documented doses of MMR or serologic evidence of measles immunity. HCW who are exposed to a case of measles may be excluded from work until they provide evidence of immunity. If exposed to measles, all, children and school/child care staff without documented immunity will be removed from work/school/child care from day 7 after the first exposure to day 21 after the last exposure. Measles is highly contagious and people can be exposed by just being in the same room as a measles case during their infectious period (4 days before onset of rash until 4 days after) . Several of the cases have potentially exposed patients in healthcare facilities, resulting in large contact investigations and persons needing immune globulin administration, post-exposure vaccination, or serologic testing for immunity. Any patient suspected of having measles should be masked immediately and promptly moved to a negative pressure room when available. Providers seeing patients in an office or clinic setting should consider options such as arranging to see suspect measles cases after all other patients have left the office, or assessing patients outside of the building to avoid having a potentially infectious patient enter the office. Notify Orange County Public Health Epidemiology immediately at 714-834-8180 (or 714-628-7008 after hours) about any suspect cases. Do not wait for laboratory confirmation before reporting a suspect case. Do NOT refer patients to Public Health without first discussing with one of our staff. DO NOT send potentially infectious suspect measles patients to a reference laboratory for specimen collection. For more information on measles, see www.ochealthinfo.com/measles .