A statement from the World Health Organization (WHO) on Wednesday has raised concern on the MERS outbreak in South Korea. WHO said that the outbreak will likely grow.

The Middle East Respiratory Syndrome first emerged in Saudi Arabia in 2012 and since then had 1,154 lab confirmed cases worldwide. With a mortality rate of 37 percent, the diseases already killed 431 individuals. Risk of death is higher among older adults.

The current outbreak that struck South Korea has so far already infected 25 people, not including the five new cases that doctors have diagnosed but have not yet been confirmed by the U.N agency. Two have died because of the disease, which is characterized by cough, fever and shortness of breath and can lead to respiratory failure.

"The outbreak is the largest reported outside the Kingdom of Saudi Arabia, where the disease first emerged in April 2012 and the vast majority of cases have occurred," WHO said in its statement. "To date, contact tracing has identified a total of 25 laboratory-confirmed cases, including the index case and among health care workers caring for him, patients who were being cared for at the same clinics or hospitals, and family members and visitors."

The first MERS fatality in South Korea was a 58-year-old woman who died because of acute respiratory failure on Monday. She is believed to have been in contact with the first person who was infected of the virus. The second victim was a 71-year-old man believed to be the sixth MERS patient.

Authorities have isolated 680 people to prevent further spread of the disease, which can be transmitted when infected individuals cough.

The first case in South Korea was confirmed on May 20. The 68-year old patient has travelled to four countries in the Middle East and developed symptoms on May 11 prompting him to seek care at two outpatient clinics and two hospitals.

WHO said that doctors did not isolate the man because he did not report MERS exposure, which led to the exposure of medical staff, hospital patients and their visitors. The man infected some patients after being exposed to him for only five minutes. Other patients may have possible spread MERS at other hospitals before they were diagnosed.

Health officials are looking for more information on how the man was exposed to MERS during his travel to the Middle East.

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