The first case of Middle East Respiratory Syndrome (MERS) has been confirmed in Thailand. It took officials four days to diagnose the 75-year-old businessman from Oman. Fifty-nine people who came in contact with the unnamed man are currently being monitored, including three of his relatives who traveled with him.

Authorities are worried the time lag in verifying the case increased risks of the virus spreading through Asia. Thailand is now the 26th country with a confirmed case of MERS since the viral disease was identified in Saudi Arabia in 2012. All 106 passengers on board the man's flight have been located and are being monitored. Those under observation have been ordered to remain at home for 14 days, Reuters reports.

The latest case in Thailand follows last month’s outbreak in South Korea, where 24 people have been killed by the virus and a total of 166 people have been infected. Kwon Deok-cheol, an official with Ministry of Health and Welfare, said at a press conference that the outbreak had “leveled off,” CNN reports.

Kwon does, however, warn that authorities “need to watch for further spread."

In the Thai case, the patient was traveling from Oman to Bangkok to get treatment for a heart problem. Thailand is popular for health tourism among Middle Eastern patients. The man is currently receiving treatment in Bangkok's Bamrasnaradura Infectious Diseases Institute. 

"The patient came to us tired, coughing ... there was no fever," a doctor from the private hospital told a press conference, Reuters reports. "So we X-rayed his chest ... we found that he could have two things, a heart condition or the MERS virus."

Fifty-eight staff members have been quarantined and masks are being given out to visitors. According to Reuters, all other operations appear to be carrying on as normal. 

“We advise the public not to panic because the patient and his family members were separated since the beginning,” Thailand's Health Minister Rajata Rajatanavin said, according to the BBC. "Our system is ready and we are monitoring the cases closely."

The World Health Organization (WHO) has called for countries in the region to step up their vigilance, review their response to disease protocols and strengthen their preparedness.

“Strong health systems using strict infection control measures would be the key to prevent the spread of the virus and protect health-care workers and others,” Dr. Poonam Khetrapal Singh, WHO's Southeast Asian regional director, said in a statement.