Some experts say single-humped camels may have played a role in the transmission of MERS. The disease has been most prevalent among people who live close to camels or drink their milk. Many people fell ill last year after attending a large camel festival in Saudi Arabia.
The coronavirus is transmitted through the air, by coughing or close personal contact. It can take up to 2 weeks until flu-like symptoms appear, including fever and coughing. It is reported that almost 40 percent of patients who contract MERS will die.
Officials in South Korea are under fire for failing to stop the disease early on. The country's health ministry says the so-called "patient zero" was a 68-year-old man, who returned from the Middle East in early May.
The man developed a high fever, and was admitted to hospital in the city of Pyeongtaek. He stayed there for three days. The patient was later transferred to another hospital, where he first tested positive for MERS.
During his first hospital stay, "patient zero" infected 36 people, including medical staff. Among them was a 35-year-old man who was staying in a different room. Health authorities say they didn't suspect he could have been in close contact with patient zero.
The 35-year-old developed pneumonia and was transferred to a hospital in Seoul on May 27. He was not kept in isolation and once there, he infected 34 other people within the hospital.