SIR – I have been waiting for an authoritative comment on the article by Roger Highfield and Charles Clover (Science, Feb. 1) suggesting that Aids began as a result of people in Central Africa eating certain chimpanzees. As none has been forthcoming, your readers – and perhaps the medical profession – might like to know of my own experience.

In 1957, as a student nurse, I was working at the Fever Hospital in Johannesburg. Patients were sent to us from all over Africa. Few could speak English, so could not describe their symptoms in detail or tell us how they might have contracted their particular illness.

I remember clearly the first patient who came in with very odd sores. A lot of tests were done – saliva, tears, blood, etc. – but we could not identify his problem, and he died. Suddenly there was a spate of similar cases, all from Central Africa and all ending in the patient’s death. The hospital asked a mission station in the Belgian Congo (as it then was) to send someone down to tell us more about their lifestyle and what they ate.

We were told that in the Congo there was an endearing little monkey, grey but with a green sheen to its coat. While other chimps and monkeys were hunted and eaten – as they still are all over Africa – these were adopted as pets and even venerated, as people believed that the green sheen had mystic powers. Despite this veneration (or perhaps because of it), I was taken aback to learn that men copulated with them, some apparently picking up some sort of virus as a result.

When we realised that we did not know how to cure these very ill men, we decided there was no point in admitting any more. They simply stayed at home and died. We called it green monkey disease; some time later our professor, Jock Gear, said he was sure they were the first cases of Aids to come to official notice.

One question remains to be answered. Presumably humans had had sexual relations with these monkeys for a very long time. So why was it only in the 1950s, and only in a relatively small area of Central Africa, that the monkeys contracted the virus, and passed it on? Where did they get it from?

Mrs POLLY KIRK
Millom, Cumbria