The MERS virus outbreak in South Korea, explained The MERS virus has been called "a threat to the entire world" by the director of the wortd Health organization. The virus, which had previously just hung around Saudi Arabia, has recently made the leap to South Korea, triggering the largest-ever outbreak outside the Middle East. Since May 2015, more than 90 people in South Korea have been infected, seven people have died, and more than 2,000 are under quarantine or observation. Seoul's mayorhas declared "war" on MERS. What made this all so surprising is that MERS which stands for Middle East Respiratory as syndrome isn't supposed to spread easily among humans. Scientists had thought of it a virus that primarily lives in animals and only seldom affects people. In the past, when MERS has made the leap to human populations, the disease hasn't gotten very far. But as it turns out, there's a lot we still don't know about MERS. It was only discovered in 2012, and the countries that previously harbored the virus, like Saudi Arabia, haven't always been transparent about their findings. Experts still don't understand exactly how MERS is transmitted, which is worrisome. And the fact that the disease is a deadly respiratory infection, from the same family as SARS (which infected more than 8,000 people during a 2003 global pandemic), has health officials on guard.