HIV-2 Infection

Human immunodeficiency virus (HIV) is an enveloped retrovirus that can be categorized into 2 distinct subtypes: HIV type 1 (HIV-1) and HIV type 2 (HIV-2). Although both viruses share similar transmission routes and can cause acquired immunodeficiency syndrome, there are important differences between them regarding epidemiology, diagnosis, and management. Although HIV-2 is less common globally, this virus is an important cause of disease in many regions. HIV-2 predominates in West Africa, but globalization has led to a sizeable number of cases in other parts of Africa, Europe, India, and the United States. The current estimation is that about 1 to 2 million people are living with HIV-2 globally, although this is likely an underestimate.

The first cases of HIV-2 were detected in the United States (US) in the late 1980s, and currently, about 1% of persons living with HIV in the US are estimated to have HIV-2. Clinicians are generally less familiar with HIV-2, and disease-specific data are lacking. This has limited our contemporary understanding of prevalence, treatment, and monitoring in comparison to HIV-1. To date, the approach to HIV-2 has largely been extrapolated from studies in HIV-1, though notable differences exist. The lower prevalence compared to HIV-1 has resulted in a paucity of drug trials or epidemiologic studies to address the current limitations in our understanding of HIV-2 management. However, given its global distribution, clinicians must become familiar with the differences between HIV-1 and HIV-2 while maintaining a high index of suspicion for HIV-2 in persons from endemic regions.