HI virus transmission chains among heterosexuals are short

Mathematical models deliver new insights

A research team from Zurich University Hospital and Zurich University has used mathematical modelling based on data from the Swiss HIV cohort study to determine that, among heterosexuals, the HI virus in Switzerland will spread only slowly.

Moreover, the team analysed the genetic sequences of HI viruses and was able to reconstruct the transmission chains. One striking feature is that although the virus often finds its way into the heterosexual group, it is unable to spread efficiently. This is down to the fact that fewer than one in two people with HIV pass the virus on, and if transmission does occur, then it tends to involve no more than two or three other people.

One possible explanation for this could be that heterosexuals, on the whole, practise safe sex with casual partners. This is inconsistent with the fact that in the case of other sexually transmitted diseases, rises in risk behaviour and transmission have been observed in recent years. This could be explained by the fact that HI viruses are less often transmitted by vaginal intercourse involving heterosexuals compared to anal intercourse. Furthermore, most people diagnosed with HIV receive immediate treatment, which stops the virus from being passed on.

The researchers now want to apply their mathematical modelling approach to high-risk groups such as men who have sex with men. The hope is that this method could, in future, be used to gain new insights into other infectious diseases, such as influenza.


University of Zurich (2017): Big Data in der Aidsforschung. Retrieved November 24, 2017, from http://www.news.uzh.ch/de/articles/2017/hiv.html