The most detailed investigation of the origins of the AIDS epidemic yet conducted has concluded that the most likely route by which HIV entered the human population was via early trials of polio vaccines in Africa.
Science journalist Edward Hooper says he has spent ten years investigating the origins of the epidemic, and has spoken to more than 600 researchers and clinicians involved in the 1950s polio vaccine studies and in the care of the earliest AIDS patients in Africa, North America and Europe.
He now believes that the most likely explanation for the cross-over of HIV from monkeys to humans was the contamination of an experimental oral polio vaccine called CHAT, developed during the 1950s by Dr Hilary Koprowski at the Wistar Institute in Philadelphia. The vaccine may have been grown in chimpanzee kidney cells, and Hooper believes that SIVcpz, the primate immunodeficiency virus closest to HIV, was able to contaminate some lots of the vaccine. He supports his argument by an extremely detailed investigation of the origins of monkey tissue used in vaccine production at the time, and a correlation of the towns and districts in which vaccination was carried out with the emergence of AIDS in the late 1970s and early 1980s. He also debunks many of the cases described as early AIDS cases from the 1940s, 50s and 60s, to show convincingly that HIV first began to infect humans and cause illness in the 1960s in the Congo and Central Africa.
In an editorial on September 3, The New Scientist endorsed Hooper's call for an international enquiry into the possibility that oral polio vaccines were contaminated in this way, calling on the World Health Organisation to test vaccine stocks still held on ice by the Wistar Institute and a research institute in Sweden.
A fuller description of Hooper's findings, and scientific reaction to them, can be read at BBC News Online
The River: a journey to the origins of HIV and AIDS (Penguin, £25) by Edward Hooper is published on September 1. A detailed review of the book, and an interview with the author, are forthcoming at aidsmap.com.
Note: This article was originally published in 1999. Read subsequent reports on a scientific meeting in 2000 which concluded that polio vaccination did not spread HIV here and here.