Some unlucky Disneyland visitors recently returned home with more than Donald Duck selfies and sunburns—they also brought back the measles. A California woman in her 20s unleashed the highly contagious virus on the Mouseketeer masses on Dec. 28. She then flew from Orange County to Seattle and back, and wasn’t diagnosed until Jan. 3.
Now at least 26 people in four states, California, Colorado, Utah, and Washington, have come down with the measles virus too, which is spread through coughing and sneezing, and can survive on hard surfaces.
The news hints that 2015 might have a shot at breaking last year’s astonishing new public health record for measles cases and outbreaks. In 2014, some 644 Americans were sickened with measles—the highest number since the virus was eliminated in 2000, when cases only originated from outside of the US by international travelers who then infect communities with low rates of vaccination. The US’s high rates of immunization mean that the virus soon dies out.
While states continue to monitor the few hundred people who have come in contact with the virus, public health officials haven’t yet indicated where the first patient contracted the virus.
One thing is clear: the Disneyland Patient Zero was unvaccinated. Those who have received immunization against measles—a two-course dose given to children between 12 and 15 months and again between the ages of four and six—don’t get it. Since it’s one of the most contagious viruses known to medical science, most parents have their children immunized as soon as they’re eligible, unless they have weakened immune systems or are allergic to the vaccine.
Until recently, that is. Thanks to the rise of the antivaxxer movement, founded on specious claims that the measles vaccine causes autism, more and more Americans leave their children vulnerable to measles. For example, as of 2002, more than 95% of California’s kindergarteners had been vaccinated; now only 92% have, making measles’ spread much more likely. And for every 1,000 who get the disease, between one and three will die from it, while another few will end up deaf or brain-damaged, reports the LA Times. The antivaxx movement is upping the chances of contraction among those who are still too young or whose immune systems are too vulnerable to be immunized.
The LA Times reported early on that three out of six people recently sickened in Orange County—which, as it happens, boasted California’s highest rates of measles infection last year—were old enough that they should already have been vaccinated. Public health authorities haven’t yet released more detailed information on why those sickened in the Disneyland and the related outbreak were unvaccinated. But recent rates suggest that a high percentage may hail from the antivaxx camp: from January to May 2014, 85% of measles patients were unvaccinated for non-medical reasons.