It's unclear whether the officer was targeted because he was traveling with Burns, who has ordered an agency-wide review of possible attacks using microwave or other directed energy.
The CIA declined to comment on the officer's case, but said that Burns "has made it a top priority to ensure officers get the care they need and that we get to the bottom of this". Since becoming director, Burns has tripled the number of medical staff studying Havana syndrome and met agency personnel who reported cases.
The officer's exposure in early September was a few weeks after two possible cases of Havana syndrome delayed Vice-President Kamala Harris' trip from Singapore to Vietnam. US officials said then that the cases were not someone who worked for the vice-president or the White House.
Giordano, professor of neurology and biochemistry at Georgetown University and executive director of the Institute for Biodefence Research in Washington, said Tuesday the intelligence officer had reported symptoms consistent with the syndrome, which generally include loss of balance, dizziness, and headaches. The officer's case "represents a clear and present threat", Giordano said.
"We're beginning to see a pattern of increased selective targeted use," he said.
New reports of possible Havana syndrome cases continue to emerge in the US and abroad, including two, as yet unconfirmed, in the US this month and a series affecting US personnel in Germany several weeks prior, Giordano said.