It was revealed by a disease control official on Wednesday. Thai authorities were treating the case as if it were the Clade 1 form of mpox, as the person, a 66-year-old European man with residency in Thailand had arrived on Aug. 14 from an African country where it was spreading, Thongchai Keeratihattayakorn, director-general of the Department of Disease Control, told Reuters.

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"After he arrives from the flight there is very little time frame where he come into contact with others," Thongchai said. "He arrives around 6 pm and on the next day, Aug 15, he went to see the doctor at the hospital."

Thongchai said the man has undergone a test to determine whether the case was a Clade 1 variant, with the result expected by Friday. Authorities are also monitoring 43 people in the country who may come into contact with the patient, he said.

The director-general did not name the African country the man had been in. He said the man had transited in a Middle Eastern country, which he also did not name, before flying on to Thailand.