How did the HIV pandemic begin?

So what’s the history of the virus? HIV was discovered by the Paris Pasteur Institute scientists Françoise Barré-Sinoussi and Luc Montagnier in 1983. But it had been circulating in humans for almost a century by then. How do we know that, though, and where did HIV come from in the first place? To shed some light on this, Adam Murphy spoke to Rowena Johnston, director of research at the Foundation for AIDS Research in New York...

Rowena - Well, HIV really is the story of the bad things that happen when a virus jumps from one species to another. In the case of HIV, there are chimpanzees that live in central West Africa, and they have a virus called Simian Immunodeficiency Virus, obviously closely related to Human Immunodeficiency Virus. And the most likely scenario is that back during the early and mid 20th century, there was a lot of building of infrastructure there in central West Africa, mainly railways; and there was a law that stated that workers on the railways had to be fed meat. So the Europeans in charge decided that the easiest way to accomplish that was to hunt chimpanzees, and I'm guessing they made the labourers do that. And in the course of butchering those animals, the chimpanzees, the blood might've made its way into cuts in the labourer's hands; and so the virus was able to make that jump.

Adam - And then how did it spread to be the epidemic and pandemic we know it as today?

Rowena - We are talking about a colonial- and upheaval-filled time in history in Africa. So we have a lot of these workers who may have acquired the infection; there was probably a lot of forced movement of many people in the country; there was poverty, there was sex work, there were vaccination campaigns, most likely needles were at least occasionally reused. And so there was probably some fairly dramatic spread of the virus for, let's say a couple of decades, the 1920s through the 1940s and 50s. You have expansion of the roads and the railways; the virus was able to travel out in all directions from central West Africa then. Certainly it headed southwards towards South Africa, which we know has the highest concentration of HIV cases today. It made its way east and north through Africa. And then in the late 1950s and early 1960s, when, for example, the Belgian Congo was going through a really rough time getting independence, the virus was able to spread across the oceans and it made its way to the Caribbean, and from there to the United States. And then it gets a little bit more speculative. It's thought that it spread from the United States to Europe and Asia and Australia, although there were probably direct introductions from Africa to Asia as well; there's a close connection between South Africa and India. But certainly we know that it was in the United States by the 1960s.

Adam - And then how do we ultimately identify it in 1983?

Rowena - Well, by the early 80s, HIV had spread to enough people around the United States that doctors noted that there was a cluster of mysterious medical cases in Los Angeles and New York, and that those cases had some commonalities. And they decided to publish about that in 1981 in the Morbidity and Mortality Weekly Report; it's a publication put out by the US CDC. And that's when we traditionally date the start of the HIV epidemic, even though we know it had been around quite a long time before that; but given the publication that allowed other doctors to identify that they also had similar cases, it took a few more years, as you notice in your introduction, to identify the virus that causes what we now call AIDS, and a couple of years after that identify the first antiviral. And really since the 80s and 90s, HIV has been incredibly interesting to scientists. It's a relatively unusual virus and it's an extraordinarily difficult virus. As you noted, it integrates into our DNA, which is quite unusual for a virus; but that combined with a few other characteristics means that HIV is not cleared by the immune system. But it's also extraordinarily difficult - really, almost impossible, but not quite - to clear the virus from the body, or in other words to cure, which is what we at amfAR are aiming to do.