Despite measles being declared eliminated in the United States in 2000, one case is breaking out daily in Washington right now, and in New York multiple state of emergencies have been declared over outbreaks of measles among heavily unvaccinated populations. Meanwhile in London a measles outbreak has affected over 300 people over the past six months.

Measles continues to be a global health issue, killing more than 100,000 people a year worldwide — and most of the casualties are under the age of five in developing countries. This is a demonstration of horrific inequality.

If you’re born into extreme poverty, you often miss out on vaccines for deadly but preventable diseases — but why is measles, suddenly causing dangerous outbreaks amongst much wealthier communities?

The answer, you may have guessed, comes down to vaccine skepticism. In this case, it’s the significant number of people in developed countries who’ve chosen not to vaccinate themselves and their children against measles and a host of other preventable diseases, which children and pregnant women are most at risk for. 

Stopping outbreaks of preventable diseases like measles starts with knowing what the disease is and how it spreads. Take our quiz to see what you know about measles.