HIV figures distorted by varying susceptibility

The recent reported decline in HIV in some countries could be due to differing levels of susceptibility to the disease rather than changing behaviour, it has been suggested.

According to an article published in the latest issue of the AIDS journal, those more vulnerable to HIV contract it during the early stages of an epidemic.

This situation then leads to a 'dying off' of the most susceptible, which can lead to a decline in the perceived level of the virus' spread without changes in sexual behaviour.

The report concluded that "a substantial heterogeneity in susceptibility to HIV infection may lead to an epidemic that peaks and then declines due to a depletion of the most susceptible individuals, even without changes in sexual behaviour".

"This effect was most notable in high-risk groups such as female sex workers and was consistent with empirical data," it added.

The study incorporated a mathematical model based on the rates of infection among Kenyan sex workers.