After a few cases here and there, measles is making a big push back into the national consciousness.
An outbreak linked to visitors to the Disneyland Resort Theme Parks in Orange County, Calif., has sickened 67 people in California and six other states according to the latest count from the Centers for Disease Control and Prevention.
So far this year there have been 84 measles cases in 14 states. That's already more cases than the U.S. typically sees in a year, the CDC's Dr. Anne Schuchat told reporters on a conference call Thursday. "This is a wake-up call to make sure measles doesn't get a foothold back in our country."
Measles is highly contagious. Ninety percent of people who aren't immune get sick after being around an infected person. Vaccination against the virus is highly effective. Schuchat said the current outbreak is happening because people haven't been vaccinated — not because the measles vaccine isn't working.
The latest wave of cases and potential infections to be identified is in Arizona. Health officials there said 1,000 people may have been exposed to measles from seven people confirmed to have been sick with measles there. Four of those cases were in an unvaccinated family that visited Disneyland.
"This is a critical point in this outbreak," wrote Will Humble, director of the Arizona Department of Health Services, in a blog post Wednesday. "If the public health system and medical community are able to identify every single susceptible case and get them into isolation, we have a chance of stopping this outbreak here. However, if we miss any potential cases and some of them go to a congregate setting with numerous susceptible contacts, we could be in for a long and protracted outbreak."
Widespread vaccination led to a decline in measles, and the disease was declared eliminated in the U.S. in 2000. Vaccination has kept the illness at bay. But the disease remains common in many countries, and travelers bring cases back to the U.S. A big bump in 2014 was tied to Amish missionaries who traveled to the Philippines when a measles epidemic was underway.
Schuchat told reporters that measles outbreaks have been much harder to control in recent years.
Children are supposed to receive their first dose of measles vaccine at a year to 15 months of age, followed by a second dose between 4 and 6. But 1 in 12 kids isn't getting the first dose on time, Schuchat said.
The "overall picture has been getting better, not worse" for vaccination, Schuchat said. But pockets where many people haven't been vaccinated, such as the Amish communities in Ohio back in 2014, provide fertile ground for the measles virus.
One issue is schoolchildren whose parents seek nonmedical exemptions from vaccine requirements. The proportion of children receiving those exemptions varies widely — from 7 percent of kindergartners in Oregon to none in Mississippi and West Virginia where they aren't allowed.
Schuchat said medical exemptions are needed. Some children, such as Rhett Krawitt, a 6-year-old boy in California boy whose immune system was compromised by leukemia treatment, can't be vaccinated. But Rhett relies on what's called herd immunity to keep him safe. His father and mother have asked the school district to bar unvaccinated children, who could pass on diseases such as measles, from attending school.
Research published Monday in the journal Pediatrics finds that people who seek personal-belief exemptions for their children often live near one another. "We think it's the microcommunities that are the problem," CDC's Schuchat said of the way that measles has erupted recently.
Data from Arizona show that the rate of nonmedical vaccination exemptions has been on the rise in recent years and varies quite a bit depending on the type of school a child attends.