The Department of Disease Control (DDC) said on Wednesday that Thailand may have its first case of a new, more transmissible strain of mpox.
The patient had arrived from Africa and the health of 43 passengers seated near him on the plane was being closely monitored.
The DDC said the patient was a 66-year-old European man who had a residence in Thailand and worked in Africa, where mpox is endemic.
He had arrived back in Thailand from Africa on Aug 14.
The following morning, last Thursday, he had a fever and noticed he had a number of small rashes. He quickly went to a hospital for an examination.
He was diagnosed with mpox, a viral disease.
The initial examination found it was not the previously found Clade 2 strain. Health officials were awaiting the results of further tests and would confirm if it was a Clade 1b-type infection. This was a more transmissible strain.
The DDC said the patient had no serious symptoms.
Thailand's first case of mpox was reported in 2022 and was Clade 2 strain. There have been about 800 cases of Clade 2 mpox since then, 140 of them this year, the DDC said.