oa HIV Molecular Epidemiology in the Middle East and North Africa: Understanding the Virus Transmission Patterns

Background: Human Immunodeficiency Virus Type I (HIV-1) is characterized by a high genetic variability. The distribution of HIV-1 subtypes in a population can help track transmission patterns and the evolution of the epidemic. The Middle East and North Africa (MENA) continues to be perceived as a region with limited HIV epidemiological data, but recent research indicates that nascent HIV epidemics appear to be emerging among high-risk groups including injecting drug users (IDUs), men who have sex with men, and female sex workers.

Objective: To review all evidence on HIV-1 subtype distribution in MENA where there remain several gaps in the understanding of the HIV epidemic.

Methods: A comprehensive systematic review of all HIV-1 molecular epidemiology data in MENA was undertaken. Sources of data included 1) PubMed, 2) country-level reports and database including governmental and non-governmental organizations publications, and 3) international organizations reports and databases.

Results: In several countries such as Lebanon, Saudi Arabia, and Yemen, a very diverse distribution of HIV-1 subtypes was observed reflecting principally travel-related exogenous exposures. A trend of a dominant HIV-1 subtype was observed in few other settings and was often linked to HIV transmission within specific high-risk core groups such as subtype A and CRF35_AD among IDUs in Afghanistan, Iran, and Pakistan; and subtype C in heterosexual commercial sex networks in Djibouti and Somalia. Subtype B was predominant in Northern Algeria, Tunisia, and Morocco, but this appeared to reflect a mix of indigenous endemic transmission and exogenous exposures of West European and North American origin.

Conclusions: Multiple introductions of HIV-1 variants due to exogenous exposures of nationals seemed common to all MENA countries, as observed from the high diversity in subtypes or the high genetic divergence among any specific subtype even if predominant. This in part reflects the high population mobility in MENA. In several countries though, epidemic-type clustering of specific subtypes suggests established or nascent HIV epidemics among classic core risk groups for HIV infection. With overall weak surveillance systems in MENA, molecular investigations could help identify the emergence of hidden epidemics among high-risk groups. HIV prevention efforts must be prioritized for these groups.