For years, there has been a robust counter-dialogue against the official position that HIV started to spread among humans following a single transmission event between an infected ape and a jungle butcher.
Skeptics point to the smallpox and polio vaccination missions conducted all throughout the Congo by nuns and nurses who used the same needle to vaccinate entire villages of people.
A new study published in the Proceedings of the National Academy of Sciences (USA) suggests the nuns didn’t do it. Or they did no more than 0 to 6% of it. The rest, it says, either can’t be explained by the vaccination theory or is better explained by sexual or vertical (mother-child) transmission. (Press release, 3 Jun 07)