Measles
Measles is a highly contagious viral disease. It is widespread in many parts of the world, including Europe, Africa, and Asia. Measles begins with a fever that lasts for a couple of days, followed by a cough, runny nose, conjunctivitis (pink eye), and a rash. The rash typically appears first on the face, along the hairline, and behind the ears and then affects the rest of the body. Infected people are usually contagious from about 4 days before their rash starts to 4 days afterwards.
The last large outbreak of measles in California was associated with Disneyland and occurred from December 2014-April 2015, when at least 131 California residents were infected with measles; the outbreak also infected residents of six other states, Mexico, and Canada.
In 2019, there were 73 confirmed measles cases in California, including 41 cases associated with six outbreaks (defined as 3 or more cases). Of the six outbreaks, five were linked to patients with international travel, while one had an unknown source. The largest outbreak consisted of 21 cases and involved multiple generations of transmission in a health care setting. The other five outbreaks involved from 3 to 5 cases.
While high levels of immunity in the general population ultimately limit measles outbreaks, measles readily spreads in communities and social networks with lower coverage.