Havana Syndrome: How it feels to suffer from the mysterious illness - 'Like being seized by an invisible hand'

The US Embassy in Cuba where diplomats first complained of the illness. Photo / Getty Images

A career US diplomat has described being seized by an "invisible hand" when she was struck down by the Havana syndrome.

Another diplomat was told her brain had aged at least 20 years as a result of the mysterious illness.

Tina Onufer, who was stationed in Havana, fell victim to the phenomenon linked to brain injuries in March 2017.

At least 200 cases of Havana Syndrome are under investigation, half involving US officials including diplomats, spies and soldiers.

Three victims - Onufer, Doug Ferguson, and his wife Kate Husband - described the debilitating impact of the syndrome on NBC.

"I felt like I was being struck with something," Ms Onufer said.

"Pain that I have never felt before in my life… mostly in my head and in my eyes… It was as if I had been seized by some invisible hand and I couldn't move.

"People don't understand what this kind of brain damage can do to you," Onufer said.

"So it's very easy for people to be dismissive and say, 'But you look fine.' But the reality is, I'm not. And I don't think very many of us are. And we just want to have our lives back."

The long-term impact of the syndrome ended her diplomatic career.

Symptoms associated with Havana syndrome, which has afflicted Americans serving at diplomatic posts in several countries. Photo / AP

Husband was also stationed in Havana when she and her partner noticed a constant annoying sound which continued for weeks.

The impact was devastating.

"The way the doctor boiled it down for me… he said, 'Well, it's like you aged, you know, 20, 25 years all at once,' she said.

She has since retired on medical grounds and still suffers from nausea and mental fogginess.

Havana syndrome was first identified in Cuba in 2016 when two dozen CIA officers complained of suffering from buzzing in their heads and intense pressure in their skulls.

Originally the US State Department suggested the cases could have been caused by the loud noise made by a breed of crickets.

That theory has since been discounted.

It is now believed the phenomenon could have been caused by the directed pulsed radio waves which were once used for intelligence gathering being turned into a weapon.