Explainer: What’s the Difference Between an Outbreak and an Epidemic?

Explainer: What’s the Difference Between an Outbreak and an Epidemic?
Liberian health workers at an Ebola treatment center in Monrovia, on October 18, 2014. Zoom Dosso/AFP/Getty Images
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More than 8,000 people have died from Ebola in West Africa since February 2014, and it has spread beyond the three countries initially affected. So, it’s an epidemic, right? Or is it an outbreak?

What about H1N1? The 2009 pandemic infected people around the world. But, so did the SARS epidemic in 2003. What’s the difference between an epidemic and pandemic? What about diseases like malaria and dengue? Dengue fever infects between 50 million and 100 million people each year in countries all over the world. So that’s the same thing as a pandemic? Not quite.