MICHAEL SMITH: MERS has wreaked havoc in the Eastern hemisphere. It stands for Middle East Respiratory Syndrome, and it's caused by a virus. We're not exactly sure how it started, but it was first reported in Saudi Arabia in 2012. It's dangerous, and can spread quickly, as we saw in Korea, where MERS infected 185 people and killed 36 in a little over a month. Those numbers are frightening, but it hasn't hit the US. Only two Americans have ever been infected, and that was while on a trip to Saudi Arabia. Both survived, and we haven't had any scares sense. There's no vaccine, and no drug to treat MERS, so if you're traveling to a country that has had MERS cases, the best way to stay safe is the way you'd protect yourself from any respiratory illness. Wash your hands. Avoid touching your face with unwashed hands. And steer clear of sharing things with sick people. If symptoms like a fever, cough, or shortness of breath show up within 14 days of travel, don't wait. Call your doctor. For WebMD, I'm Dr. Michael Smith.