Dr Apirak Pisutarporn, Sa Kaew medical chief, said that his agency will examine all kindergartens in the province as a preventive measure.

In some cases, footandmouth disease is not severe and those infected can recover within five to seven days.

However, the case of the Kilosong kindergarten pupil was severe and is extremely rare in Thailand.

“Therefore the school will be closed for two weeks, not one as earlier said, to completely pass the incubation period.” The kindergarten was closed on Wednesday after the boy died.

“We are examining the source of the disease. From what the parents of the boy said, they got in touch with Cambodians and their children. However it could not be confirmed yet if the disease is from Cambodia,” Apirak said.

The boy’s father said earlier that he took the boy and his sister to Klongluek border market in the province many times.

Apirak said he is now seeking information from the Cambodian side to find out if the disease is spreading.

The boy’s sister, who is being treated for the same symptoms in Siriraj Hospital in Bangkok, is believed to be recovering.