A total of 175 people were exposed to Thailand's only case of Middle East Respiratory Syndrome (MERS) and the patient's condition has improved, the health ministry said on Saturday.
In a statement, the ministry said it had been in touch with all 175 and had instructed them to stay away from public spaces and for medical personnel to monitor their health.
In South Korea, the health ministry said that no new cases of the disease had been recorded in the country for the first time in 16 days. Health authorities said on Friday the outbreak first reported on May 20 seemed to have leveled off.
South Korea's health ministry said later on Saturday that a 63-year-old male MERS patient with an existing heart ailment and diabetes had died, becoming the 25th fatality in an outbreak that had spread through hospitals and infected 166 people.
On Friday, Thai health minister Rajata Rajatanavin told reporters the chances of a MERS outbreak in Thailand like the one in South Korea were low as the authorities had isolated the patient quickly.
The virus was first detected in Thailand in a 75-year-old man from Oman who traveled to Bangkok for treatment of a heart condition.
On Thursday, the man was moved from Bumrungrad International Hospital to an infectious diseases facility.
Three relatives of the man are also being kept in isolation rooms at the institute and had tested negative for the virus, Surachet Satiniramai, acting permanent secretary at the health ministry, said on Saturday.
"The condition of the MERS patient is better overall," he said. "The chest x-rays show improvement and he can eat soft food."
Thai authorities have said it had taken nearly four days to confirm the illness.
Doctors at Bumrungrad Hospital said on Friday that it quarantined 58 staff members but that there had been no panic, with no patients at the hospital asking for transfer to other facilities.
MERS was first identified in humans in Saudi Arabia in 2012 and the majority of cases have been in the Middle East. Scientists are not sure of the origin of the virus, but several studies have linked it to camels.
Isolated cases have cropped up in Asia before South Korea's outbreak.
(Reporting by Aukkarapon Niyomyat in Bangkok and Jack Kim and Ju-min Park in Seoul; Writing by Amy Sawitta Lefevre; Editing by Richard Borsuk and Raissa Kasolowsky)