How Did HIV Originate?

HIV originated from a group of viruses called Simian Immunodeficiency Viruses (SIVs), which naturally infect African primates. The crossover into humans occurred through multiple independent transmission events, primarily in Central and West Africa.

The Two Types of HIV

• HIV-1: The most common and virulent type, responsible for the global pandemic. It originated from SIVcpz in chimpanzees and SIVgor in western lowland gorillas in Central Africa.

• HIV-2: Primarily restricted to West Africa and less transmissible. It originated from SIVsmm in sooty mangabeys.

How the Jump Occurred — The Hunter Theory

The leading scientific explanation is the “Hunter Theory”:

1. Direct contact: Hunters in Africa were likely exposed to infected primate blood while hunting or butchering animals for food.
2. Infection: The virus entered the human bloodstream through small cuts or wounds.
3. Adaptation: While these viruses were often cleared by the human immune system, on several occasions they adapted to survive and spread between humans.

Conclusion

HIV is a zoonosis: it crossed from primates (chimpanzees and sooty mangabeys) to humans, probably through contact with infected blood during hunting or butchering. Understanding this origin underscores the importance of zoonotic surveillance and safe handling of wildlife and bushmeat.