MERS or (Middle Eastern Respiratory Syndrome) is caused by a caronavirus which is the same family of viruses that cause the common cold.

According to the Center for Disease Control and Prevention, MERS tends to spread due to having close contact with an ill person. The outbreak in South Korea and deaths associated were mostly among people with preexisting conditions. Experts from the WHO are heading to South Korea to assess the pattern of the spread of the virus and evaluate public health response efforts.

The outbreak in South Korea has been the largest outside Saudi Arabia -- where the virus was discovered in 2012 but beyond that scientists don't really know where it came from and the inner workings of the disease. Researchers say they've isolated the MERS virus in two camels and 3/4 of camels in Saudi Arabia tested positive for past MERS exposure. But most is still unknown regarding the way humans contract the disease. What scientists do know is  it's affecting those who have lived or traveled to the Arabian Peninsula.

MERS doesn't transmit easily. Doctors and scientists do not know the exact source of or mode of how it spreads. This disease only surfaced 3 years ago. About 1/3 of people who contract MERS die from the disease. Most of the people infected had an additional underlying medical condition. Those with weakened immune systems are at a hgiher risk for contracting MERS or a more aggressive case. Treatment includes rest, fluids pain relievers but nothing beyond that. 

Symptoms include:

• fever
• cough
• shortness of breath
• nausea
• vomiting
• diarrhea

Steps to prevent MERS from the CDC

• Wash your hands often with soap and water for at least 20 seconds. Use an alcohol-based hand sanitizer if soap and water are not available.
• Cover your nose and mouth with a tissue when you cough or sneeze, then dispose of the tissue.
• Avoid touching your eyes, nose and mouth with unwashed hands.
• Avoid personal contact, such as kissing, or sharing cups or eating utensils, with sick people.
• Clean and disinfect frequently touched surfaces and objects, such as doorknobs.

The death rate from MERS, first identified in humans in 2012, has been 38 percent, according to WHO figures, with older patients and those with existing respiratory and renal ailments at greater risk, according to a South Korean doctor. 

However, experts said that figure may overstate the fatality rate as patients with little or no symptoms might go undetected.

By comparison, the death rate from SARS was 9 to 12 percent, rising above 50 percent for patients over 65, according to the U.S. National Library of Medicine.

The WHO has so far not recommended trade or travel restrictions for South Korea.

But South Korean border control authorities have put a ban on overseas travel for people isolated for possible infection, a health ministry official said.