Yinka Adeymi carries a whole different order of guilt. He played a small part in one of the greatest tragedies of our time.

The Nigerian journalist was there at the beginning of the AIDS crisis - and blew the story.

He can explain why it happened. He can even justify it. But he can't live with the result.

Adeymi talked about the episode at an international gathering of journalists recently to show how prejudice and politics can prevent an important message from getting out.

In 1984, he was a young correspondent for the News Agency of Nigeria. He was sent to Dakar, in nearby Senegal, to cover an international scientific conference on a mysterious new disease called AIDS that seemed to destroy the body's immune system. At the time, it affected mainly intravenous drug users, blood transfusion recipients and homosexual men. Most of the known cases were in the United States.

All of the top virologists in the world were at the Dakar meeting, including Robert Gallo, the co-discoverer of the human immunodeficiency virus (HIV). The main topic of discussion was a new theory that the deadly virus originated in Africa's green monkeys, then jumped species to humans.

"That was the first organized forum where the suggestion was made that HIV/AIDS actually began in Africa," Adeymi said. "As a reporter and participant, I recall my feeling of anger and disgust at the green monkey theory.''

He wrote a searing report, dismissing the theory as the work of lazy, neo-colonial western scientists. It was translated into three languages and syndicated all over Africa, helping to shape public attitudes.

"Africans didn't believe the western hype about AIDS and did not do anything about it," he recounted.

Five years later, the first cases of AIDS showed up in Nigeria. Today, an estimated 6 million Nigerians are infected.

In sub-Saharan Africa, 24.5 million people are living with HIV/AIDS. Nearly 16 million African children have lost at least one parent to the disease.

As Adeymi watched the epidemic sweep across Africa, he reflected uneasily on his role in the tragedy. Might things have been different if he had been more open-minded in Dakar?

In a technical sense, his skepticism was warranted. The green monkey theory did turn out to be scientifically unsound. Researchers are still debating the origin of AIDS.

But Adeymi blames himself for not seeing the larger issue. He allowed his distrust of the West to blind him to an impending health disaster.

Seventeen years later, he is on the front lines of the global battle against AIDS.

He lives in New York, owns a public relations company and runs a website called nigeriatoday.com, which he uses to encourage expatriate Nigerians to support HIV/AIDS testing, help educate young people about the disease and promote the distribution of condoms in their homeland.

Adeymi's proudest achievement is a just-released media handbook for western scientists seeking to conduct HIV vaccine trials in Africa. He is determined to help break the cultural barrier that once prevented him from doing what was best for Africa.

The 42-page booklet, published by UNAIDS, the global agency co-ordinating the AIDS battle, tells medical researchers in plain language how to deal with the fears and suspicions they are likely to encounter in Africa.

It warns them not to assume that they'll be regarded as saviours and not to get so caught up in promoting their vaccines that they forget how desperate and frightened people in Africa are.

Adeymi walks scientists through a typical press conference; an encounter with a hostile journalist; a claim by an HIV-negative volunteer that he/she has been infected during the vaccine trials; a run-in with a community organization opposed to human drug testing; a disagreement among medical researchers midway through a vaccine trial.

He urges them to keep their emotions in check. "Most journalists who take an interest in vaccine work and trials are likely to be driven by a messianic instinct to protect society from harm," he says. "Don't get angry. Listen attentively and you will probably find that the person is scared of the damage he thinks your vaccine would do.''

The handbook has gone out to approximately 200,000 scientists. Adeymi is the first to admit that it is a small weapon in the global battle against AIDS. But if the western scientists whom he encountered in Dakar 17 years ago had been a little more sensitive, he might have been a little less dismissive.

There are three remarkable things about Adeymi's story.

The first is that he tells it openly, despite his own discomfort.

The second is that he takes responsibility for his mistake, although his attitude was no different from those of other African journalists.

The third is he is trying to do as much good, as he once did harm.

Adeymi doesn't expect plaudits. But he deserves them.