A medical staff member wearing a protective suit waits to enter an isolation ward for patients with Middle East respiratory syndrome, or MERS, in South Korea. Ed Jones/AFP/Getty Images hide caption

itoggle caption Ed Jones/AFP/Getty Images

A woman on a street in Seoul checks her cellphone. The government is ramping up efforts to control an outbreak of the Middle East respiratory syndrome by monitoring the smartphones of those under quarantine. Ed Jones/AFP/Getty Images hide caption

itoggle caption Ed Jones/AFP/Getty Images

Patient one: A businessman brought the Middle East respiratory syndrome to South Korea in early May. Since then, he has likely spread the virus to more than 20 other people. Several of those have passed the virus onto others. Maia Majumder/Health Map hide caption

itoggle caption Maia Majumder/Health Map

A student wearing a face mask stands in a public square in Seoul on June 3. More than 200 primary schools shut down as South Korea has struggled to contain an outbreak of the MERS virus. ED JONES/AFP/Getty Images hide caption

itoggle caption ED JONES/AFP/Getty Images

Since the first case on May 20, confirmed cases of Middle East respiratory syndrome, or MERS, have swelled to at least 30 in South Korea. Chung Sung-Jun/Getty Images hide caption

itoggle caption Chung Sung-Jun/Getty Images

A South Korean walks through a market in Seoul wearing a mask. South Korean President Park Geun-Hye scolded health officials over their "insufficient" response to an outbreak of the MERS virus. Ed Jones/AFP/Getty Images hide caption

itoggle caption Ed Jones/AFP/Getty Images

In this photo from 2014, passengers walk past the Middle East respiratory syndrome quarantine area at Manila's International Airport in the Phillipines. The virus is now raising public concern in South Korea. Aaron Favila/AP hide caption

itoggle caption Aaron Favila/AP

Middle Eastern Respiratory Syndrome virus particles cling to the surface of an infected cell. NIAID/Flickr hide caption

itoggle caption NIAID/Flickr

A rogues gallery of the viruses (left to right) that cause MERS, SARS, and influenza. Niaid; 3D4Medical; Niaid/Science Source hide caption

itoggle caption Niaid; 3D4Medical; Niaid/Science Source

A farmworker in Riyadh, Saudi Arabia, wears a mask to protect against Middle East respiratory syndrome earlier this month. The MERS virus is common in camels. Fayez Nureldine/AFP/Getty Images hide caption

itoggle caption Fayez Nureldine/AFP/Getty Images

Fearful of catching the MERS virus, workers wear masks during a soccer match on April 22 at King Fahad stadium in Riyadh. Fayez Nureldine/AFP/Getty Images hide caption

itoggle caption Fayez Nureldine/AFP/Getty Images

Jockeys take their camels home after racing in Egypt's El Arish desert. The annual race draws competitors from around the Middle East, including Saudi Arabia, where camels carry the Middle East Respiratory Syndrome virus. Nasser Nouri/Xinhua /Landov hide caption

itoggle caption Nasser Nouri/Xinhua /Landov

Camel jockeys compete at a festival on the outskirts of Saudi Arabia's capital Riyadh, a focal point for the Middle East respiratory syndrome virus. Fayez Nureldine/AFP/Getty Images hide caption

itoggle caption Fayez Nureldine/AFP/Getty Images

The source? Signs of the Middle East respiratory syndrome virus have been detected in camels on the Arabian Peninsula. But it's still a mystery how people catch the disease. Sean Gallup/Getty Images hide caption

itoggle caption Sean Gallup/Getty Images

So cute, but not cuddly. The Egyptian tomb bat, Taphozous perforatus, is a likely carrier of the Middle East respiratory syndrome virus, or MERS. Courtesy of Jonathan H. Epstein/EcoHealth Alliance hide caption

itoggle caption Courtesy of Jonathan H. Epstein/EcoHealth Alliance

A dromedary camel waits for a tourist to hop on its back in Petra, Jordan. The country has recorded two cases of the Middle East respiratory syndrome. Chris Jackson/Getty Images hide caption

itoggle caption Chris Jackson/Getty Images