The human immunodeficiency virus (HIV) was first discovered in 1983. In 2009, it was estimated that 33.3 (31.4 -35.3) million individuals are infected with HIV worldwide. In that year 1.8 (1.6-2.1) million people died from HIV. Although the virus continues to spread, the number of new infections has fallen from an estimated 3.2 (3.0 -3.5) million in 1997 to 2.6 (2.3 – 2.8) million in 2009. There are several explanations for this decrease. First, the use of antiretrovirals has slowed down the epidemic by suppressing viral replication and thereby the HIV RNA load [2]. This RNA load is a key factor in determining transmissibility of HIV. Second, sexual risk behaviour has decreased in most countries. Third, HIV prevalence follows an ‘S’ curve, like any infectious disease where it start slowly and gradually. In the final phase of the epidemic, people are either no longer infectious (due to effective treatment) or deaths outnumber new cases, so that the total number alive and infected passes its peak and begin to decline or reach a plateau. The majority of new HIV infections continue to occur in sub-Saharan Africa. Here, an estimated 1.8 (1.6 -2.0) million people were newly infected in 2009 and 22.5 million (20.9 -24.2) people were living with HIV in this region (figure 1). In Europe, the HIV-1 epidemic is much smaller, with an estimated 130,000 (110,000-160,000) newly infected in Western and Central Europe in 2009. This results in 820,000 (720,000-910,000) individuals living with HIV-1 and a prevalence of 0.2% in this region.

HIV, epidemiology, immunology, infectious diseases, virology
C.A.B. Boucher (Charles)
Erasmus University Rotterdam
Financial support was provided by the European Union, through the FP7 grant DynaNets (no. 233847) and the Virolab project (IST-027446), ViroClinics Biosciences BV, J.E. Jurriaanse Stichting, Boehringer Ingelheim BV, and Virology Education BV
This work was funded by the European Commission 7th Framework Programme; grant id fp7/233847 - Computing Real-World Phenomena with Dynamically Changing Complex Networks (DYNANETS), This work was funded by the European Commission 7th Framework Programme; grant id fp7/223131 - Collaborative HIV and Anti-HIV Drug Resistance Network (CHAIN)
Erasmus MC: University Medical Center Rotterdam

Frentz, D. (2012, September 26). The Epidemiology of HIV-1 Transmitted Drug Resistance. Erasmus University Rotterdam. Retrieved from