A total of 51 measles cases have now been reported in the wake of an outbreak linked to Disney theme parks in Anaheim this December, with all but nine cases directly connected to the park, health officials said.
The total rose to 51 after Orange County confirmed that 16 people have come down with the measles there as of Friday afternoon.
The source of six of those cases was unknown, in a sign that the illness's outbreak was more widespread than previously thought, Orange County health officials said -- the sick people hadn't been to Disneyland or been in contact with confirmed cases that were associated with Disney.
The measles outbreak is expected to continue spreading, since the six non-Disney cases "indicates exposure to measles is more widespread throughout the county," the Orange County Health Care Agency said in a press release Friday.
There were measles cases in the following California counties: San Diego (10), LA (8), Alameda (4), Ventura (3), Riverside (2) and San Bernardino (2). Six other cases related to the Southern California outbreak were confirmed in three U.S. states and Mexico.
Because health agencies have different reporting requirements, up-to-the-minute information can be hard to come by; by Saturday, the OCHCA reported higher numbers in Orange County than the state did.
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The extent of the outbreak was tabulated by combining reports from the California Department of Public Health, OCHCA and Associated Press. It was first reported by the Los Angeles Times.
People with measles are contagious for about four days before a characteristic rash appears, along with fever, cough and watery eyes, health authorities say. Anyone who thinks they have measles should call a doctor before seeking help, so they don't expose others to the illness.
The illness was mostly eradicated in the U.S. through vaccines. Authorities think measles comes to the country from overseas -- there were 644 measles infections in 27 U.S states last year, many brought over from an epidemic in the Phillipenes, the Associated Press reported.
NBC4 reporter Matthew Glasser and The Associated Press contributed to this report.