Origins of HIV AIDS

Origins of HIV/AIDS
By Alex Kituli

Where did HIV come from? This question has been one of controversy since the outbreak of the epidemic, and many maverick and even lunatic theories have been aired, including it being a virus from space deposited by a passing comet or aliens, or God’s revenge on a sinful world. The origins of the virus pale into insignificance compared to the battle of fighting it. With HIV spreading through poor populations and in particular in Africa, and despite the availability of antiretroviral medication in the West, it is a global problem of gargantuan proportions with 2.4 million deaths due to, and over 25.3 million people continuing to live with, HIV infection in sub-Saharan Africa alone in 2000.

Indeed, investigation of the origins is a sidelined study in the field of HIV research, deemed somewhat unimportant in the face of such an overwhelming task of fighting the infection. The British National Aids Manual (NAM) 1998/9 states “Scientific investigation of origins may help us understand how to combat HIV most effectively. However, it is extremely important to distinguish this from irresponsible speculation about ‘where it came from’”, before adding, somewhat cryptically, “origin does not equal cause”.

However the NAM warning seems to be guarded against the fact that speculation about the origins of the virus have a particular use in the popular press, and that it is used to blame particular individuals or social groups. These typically have been those most affected by the virus: the marginalized and poor of the world, its association with sex, prostitution and drug use emphasises this. Thus, as it was first identified in American homosexuals, they were also blamed for bringing it into the world, and blamed for their own misfortune. This was quickly deflected into Haiti, a very poor country dependent on tourism for its public revenue, and thence into Africa, the poorest and most marginalized continent.

Where the virus came from is important to understand in terms of disease prevention. While the prevention of onward transmission of the virus has currently failed, knowing the origins of the virus may prevent further agents becoming widespread in the population. What makes the origin issues hard to resolve is that the HIV virus has a long incubation period. Diseases such as Ebola haemorrhagic fever are easier to transmit, but also have a very short incubation time: an epidemic is easy to identify due to horrifying and identifiable symptoms, and easy to isolate. HIV, on the other hand, incubates for about nine years. There are few symptoms until the immune system starts to collapse. Thus with a delay of nine years, tracking the ‘source’ is difficult.

A number of theories have been proposed and, indeed, hotly contested. Firstly, however, there is some agreement on the ancestor of the HIV virus. HIV-1 is related to a Simian retrovirus found in some chimpanzees. This virus, called SIVcpz, is generally agreed to be the ancestor of the HIV-1 virus. Indeed, genetic information on the virus is collected in Los Alamos in the United States in a specific public access database (http://hiv-web.lanl.gov). Curiously, the ancestor if HIV-2 also has a simian ancestor, SIVsm – the SIV that is found in sooty mangabeys. SIVs have been observed to cause a collapse in the immune system of certain primates, however, in others, they appear to be asymptomatic (resolving in no immune damage and the host and virus appear to be attenuated to each other).

Given this general consensus on the ancestor of the virus, the question has largely become: how did SIVcpz enter into humans? There are roughly two explanations: the natural transfer theory, and two more controversial theories that propose human intervention as unwittingly introducing the virus.