Global trends in molecular epidemiology of HIV-1 during 2000-2007

Abstract

Objective: To estimate the global and regional distribution of HIV-1 subtypes and recombinants between 2000 and 2007.

Design: Country-specific HIV-1 molecular epidemiology data were combined with estimates of the number of HIV-infected people in each country.

Methods: Cross-sectional HIV-1 subtyping data were collected from 65 913 samples in 109 countries between 2000 and 2007. The distribution of HIV-1 subtypes in individual countries was weighted according to the number of HIV-infected people in each country to generate estimates of regional and global HIV-1 subtype distribution for the periods 2000-2003 and 2004-2007.

Results: Analysis of the global distribution of HIV-1 subtypes and recombinants in the two periods indicated a broadly stable distribution of HIV-1 subtypes worldwide with a notable increase in the proportion of circulating recombinant forms (CRFs), a decrease in unique recombinant forms (URFs) and an overall increase in recombinants. In 2004-2007, subtype C accounted for nearly half (48%) of all global infections, followed by subtypes A (12%) and B (11%), CRF02_AG (8%), CRF01_AE (5%), subtype G (5%) and D (2%). Subtypes F, H, J and K together cause fewer than 1% of infections worldwide. Other CRFs and URFs are each responsible for 4% of global infections, bringing the combined total of worldwide CRFs to 16% and all recombinants (CRFs along with URFs) to 20%.

Conclusion: The global and regional distributions of individual subtypes and recombinants are broadly stable, although CRFs may play an increasing role in the HIV pandemic. The global diversity of HIV-1 poses a formidable challenge to HIV vaccine development.

Figure 1. Global distribution of HIV-1 subtypes and recombinants in 2000–2003 and 2004–2007

The number of infections caused by HIV-1 subtypes and recombinants are represented as a proportion of the global total number of people living with HIV-1 in 2000–2003 (A.) and 2004–2007 (B.) (see Table 2A). The colours representing the different HIV-1 subtypes are indicated in the legend on the left-hand side of the figure.

Figure 2. Regional distribution of HIV-1 subtypes and recombinants in 2000–2003 and 2004–2007

The world was divided into 15 regions consisting of groups of countries as specified in the Methods. Countries forming a region are shaded in the same colour. Pie-charts representing the distribution of HIV-1 subtypes and recombinants in each region in 2000–2003 (A.) and 2004–2007 (B.) are superimposed on the regions. The pie-charts were prepared using the data presented in Table 2B. The colours representing the different HIV-1 subtypes are indicated in the legend on the left-hand side of the figure. The relative surface areas of the pie-charts correspond to the relative numbers of people living with HIV in the regions (Table 1). Disclaimer: The boundaries and names shown and the designations used on this map do not imply the expression of any opinion whatsoever on the part of the World Health Organisation or the Joint United Nations Programme on HIV/AIDS (UNAIDS) concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate borderlines for which there may not yet be full agreement.

Figure 3. Global distribution of individual HIV-1 subtypes and recombinants in 2004–2007

For each subtype/recombinant indicated each of the 15 regions is shaded according to the proportion of the global number of infections caused by the subtype/recombinant present in each region.