HIV-2 is a retrovirus that is distinct from but related to HIV-1. It is found primarily in West Africa and in countries with large populations of West African immigrants. Although HIV-2 is less pathogenic than HIV-1 and most patients with HIV-2 do not have progressive disease, it is similar to HIV-1 in that it, too, can lead to immunosuppression and AIDS. It is important to distinguish between the two viruses because some antiretroviral agents that are effective against HIV-1 should not be used for HIV-2.
Clinicians in New York City should consider HIV-2 in the differential diagnosis of any patient from a West African country who presents for HIV testing and/or has signs and symptoms of unexplained immunodeficiency. Most enzyme immunoassays that are currently used for screening can detect antibody to HIV-1 and HIV-2 (plus HIV-1 Group O). However, confirmatory HIV-1 Western blot tests may be negative or indeterminate. Commercial HIV-1 viral load assays cannot detect HIV-2.
The NYCDOHMH offers a multi-step diagnostic testing protocol to confirm HIV diagnosis and distinguish between HIV-1 and HIV-2.