For years a long-standing origin theory of the emergence of the HIV-AIDS epidemic in the human population is that it was a zoonotic disease (i.e. it was transfered from a different infected primate species than man) that crept out of sub-saharan Africa, this is also a belief that has crept into the lay public’s mind. Well, this paper challenges those theories and assumptions. The points I found most interesting were;
(ii) Despite long-term and frequent human exposure to SIV-infected monkeys in Africa, only 11 cross-species transmission events are known, and only four of these have resulted in significant human-to-human transmission, generating HIV-1 groups M and O and HIV-2 groups A and B. The closest relatives of SIVcpz (HIV-1 group N) and of SIVsm (HIV-2 groups C-H) are extremely rare, with only six HIV-1 group N-infected patients and only single individuals known to be infected by HIV-2 groups C-H. SIV, while capable of cross-species transmission, is thus poorly adapted for disease and epidemic spread. If AIDS were a zoonosis that is capable of significant human-to-human spread, there would be a plethora of founder subtypes and groups.
(iii) Human exposure to SIV is thousands of years old, but AIDS emerged only in the 20th century. If AIDS were a zoonosis that spread into the human population, it would have spread to the West during slave trade
So at which step did the simian derived HIV mutate into the HIV-AIDS that we now face, and what set it off? Was there immunities that non-subsaharan Africans had that blocked the emergence of the epidemic when they met the subsaharans? Or was there a genetic profile that another group had that when mixed with the non-AIDS HIV transformed it into the epidemic? Interesting questions that might help us stop future diseases.
Posted by scottm at 07:27 PM