Why do some progress faster to Aids than others?

A question I often get asked: How come some people with HIV seem to progress to Aids and death faster than others?

The rate of progression from HIV to Aids to death varies between individuals. The average time from HIV infection to Aids in the absence of antiretroviral drugs is normally 10 years.

Some succumb sooner—these are called rapid progressors, others much slower—slow progressors.

Slow progressors can remain healthy for another 20 years and some with very low viral levels who can go without taking any treatment are called elite controllers. And on the far extreme are individuals who are almost ‘immune’ to HIV infection such as a small group of commercial sex workers in Kenya.

It is estimated that one in 500 people are slow progressors or long-term non-progressors—they have low viral loads, CD4+ counts in normal range and do not take anti-retrovirals.

A lot of these people may not even know that they are infected. Rapid progressors, about 10 percent of people, in the absence of ARVs can progress to Aids and death within one to four years after primary infection. It was controversially thought that the African community was more prone to rapid progression, but this view has been debated.

A number of factors influence an individual’s progression: immune function, health, infection with other diseases such as TB, genetics, host susceptibility and the genetic make-up of the virus.

There are people, who by all accounts of their alcohol abuse, bad diet, lack of exercise, poor health, one would expect to get sick faster, but they do not and vice versa, people who otherwise live healthy lifestyles who get sick sooner.

Much research has been devoted to studying the different progressor groups, as they can provide a valuable understanding of the clinical course of HIV. By identifying factors that influence rapid progression, treatments can be designed to prevent such an event.

Genetics is one of the areas HIV researchers are very interested in. Genetics is a branch of science that studies heredity and the variation of inherited characteristics.

Our bodies are made of cells and in each cell we have genes. Genes are biological substances we inherit from our parents, which provide instructions, for example, on they way we look and how our immune system functions.

Researchers use genetic tools to take a very close look at what makes those lucky few individuals control their HIV without drugs. Scientists are beginning to discover specific genes involved in Aids progression.

Once a biological property that is common in all elite controllers is identified, the next step is to look for a drug that can safely produce the same effect in everybody else.