Disneyland Measles Outbreak Continues to Spread

The measles outbreak is growing with 59 confirmed cases in California—18 more than last week—and some 42 of those illnesses have struck people who were exposed at Disneyland in December, California health officials said Wednesday.

State health departments in California, Colorado, Utah and Washington and have confirmed cases of the extremely contagious virus, the Los Angeles Timesreported on Wednesday. Taken together, the cases would account for almost 12% of the expected measles cases for the entire year (there are 220 cases per year on average, according to the Centers for Disease Control and Prevention).

The numbers also reveal an alarming trend: Among those known cases, five people had received two or more measles vaccinations and one person had received at lease one dose of vaccine. At least 32 of those infected people are aged 20 or older, accounting for 63 percent of the outbreak, health officials said.

Indeed, many adults who were vaccinated for measles decades ago as children are now highly susceptible to the virus—perhaps as many as one in 10 of those who were immunized, infectious disease experts say.

That’s because as the years pass, people lose their original protections from childhood vaccines that come in the form of disease-battling antibodies and “memory cells” that attack infections if the body is ever again exposed, doctors say.

Of the five employees at Disneyland and Disney California Adventure in Anaheim, three have fully recovered and returned to work, and two remain off, said Dr. Pamela Hymel, the chief medical officer for Walt Disney Parks and Resorts.

All of Disney’s “cast members,” as it calls park employees, have been offered immunity tests and vaccinations since the company first heard of the outbreak Jan. 7, Hymel said. Those who have been in close contact with infected employees are put on paid leave until their immunity can be established.

The virus is highly contagious, can live for up to two hours on surfaces and is transmitted through an infected person’s coughs or sneezes. Measles is so contagious that “90% of the people close to that person who are not immune will also become infected”, according to the CDC.