South Korean health officials isolated nearly 700 people on Monday in an effort to stop the spread of the potentially deadly Middle East Respiratory Syndrome within its borders after 18 people became infected over the past 10 days -- a rate of transmission that appears more aggressive than in other countries.

South Korea has been on high alert since May 20 when a 68-year-old man who had been traveling in Bahrain tested positive for the virus. Since then, the virus has been detected in a number of patients and visitors to the hospital where he was treated -- triggering global concern about whether the virus had mutated or genetic or environmental factors may have been at play.

MERS, a coronavirus, is related to the one that infected thousands during the 2003 outbreak of Severe Acute Respiratory Syndrome and has no cure or vaccine.

"We must find the reason for the high rate of transmission unlike in the cases of other countries," President Park Geun-hye told a meeting on Monday, according to Reuters.

The Associated Press reported that 682 family members, medical staff and others who had had close contact with the man who tested positive for the virus had been isolated in their homes or in state-run facilities. The country is considering imposing a travel ban on those individuals as well.

Since being first reported in 2012, MERS has been mostly contained to Saudi Arabia, the United Emirates and Jordan. The World Health Organization says that 1,150 case have been reported and 427 of the patients have died. The WHO detailed the status of the two most recent cases:

— WHO