Thanks Elizabeth, for this look into history of a major killer. Academic interest, maybe. Learning about the factors of the spread of disease IS interesting to me.

XX

Further to Michael’s comments, the point is that you don’t have to have sex or share needles with a monkey for your bodily fluids to come into contact with theirs. Killing an infected simian (whether ape or monkey), slaughtering one, or even being bitten by one could all do that as well.

Roger,

The mainstream theory is that it was the formation of cities in the colonial era that allowed HIV to spread. Previously, if someone in a relatively isolated community, such as a group of pygmies in the foothills of the Rwenzori or on the banks of the Zaire, were to be infected, the disease wouldn’t have much chance of spreading beyond them and their immediate contacts, and would eventually die out. In latter days, cities, roads and the huge displacement of people that followed from colonialisation allowed the disease to spread into much larger communities. We even have two different types of HIV that are believed to have crossed at two different times from different ancestral simian viruses – HIV-1 and HIV-2. Of course, I would agree that the interest is largely academic; but many of the alternative theories are used to block vital medical interventions. (For instance, the polio vaccine theory has led to many people refusing vaccinations, mortality from vaccine-preventable diseases, and is a key factor in the stalling of the Polio Eradication effort in Africa).

It may be that cross species contamination has occured and was followed by genetic changes leading to HIV, but that has yet to be proved. We might never know how it happened, and I am not sure it matters beyond the acadmic interest.

Another way is the rapid development or towns during the colonisation process that brough together a large number of people who whilst sexually mixing together provided a highway for HIV development.