"I thought about just sending other people on the programme, but I feared if I didn't go myself, it might get me into trouble," he told me. "I also thought, 'Why not? It can't do any harm.'"

That was where Ceesay was wrong. It was only when he arrived at the president's makeshift clinic at State House that the ground rules of the programme were explained. No smoking, or drinking tea or coffee. No sex. And crucially, no taking of mainstream medicine - including the anti-retroviral drugs given to him by his regular doctors.

There was no backing out now, though. Jammeh's armed bodyguards were stationed at the clinic doors. For the next six months, they said, no patient would be allowed to leave without his permission.

And so the treatment began. Each morning the president would rub a mysterious green paste into the patients' bodies, while chanting prayers from a leather-bound Koran. Then, twice per day, they would drink from a bottle filled with a yellow herbal potion. Jammeh refused to say what was in it, despite being told that if he really had found a cure for HIV he could make Gambia rich overnight.

Whatever it was, it gave Ceesay constant diarrhoea. He also caught tuberculosis from another patient, and eventually grew so weak that he had to be transferred back to a proper hospital. Tests then showed that his HIV viral load had soared, and he was put back on the ARVs again.

Ceesay was among the lucky ones. His wife, who was also HIV-positive, died during the herbal programme - and so too, he says, did the majority of other patients. "As a senior figure in the HIV group, I was attending funerals all the time," he says.

That, though, was not the picture promoted by President Jammeh, who press-ganged patients into appearing on Gambian state TV to sing the programme's success. Among them was Ousman Sowe, who had a degree in public health from Britain's Leeds University. Hoping to give the programme some academic gravitas, Jammeh had recruited Sowe as its spokesman, to try to rebuff the doubts of incredulous foreign journalists.

At one point, Sowe told a BBC reporter that he had "100% confidence" in the cure. In fact, giving up his ARVs had left him so weak that he could barely climb a flight of stairs. "As an educated person, I knew it was all rubbish," Sowe remembers. "But I couldn't say anything against it, even though people were dying."

Ousman Sowe and other survivors want Yahya Jammeh to face trial

Sowe and his fellow patients are now working with Aids-Free World, a US campaign group which wants charges to be brought against Jammeh over the programme. It says it is potentially one of the biggest human rights scandals committed by his regime.

What is more, unlike his secret prisons and torture chambers, it was carried out as the world looked on. Jammeh wasn't too keen on scrutiny, though. A senior UN health official who raised objections was kicked out of The Gambia early on.

In the end, some 9,000 people are believed to have been treated, although since Jammeh kept all the clinic's records secret, nobody has yet established just how many of them died. One thing now seems certain, though - the only "miracle" about his cure was that anyone survived at all.