Longstanding presence of HIV-2 infection in Guinea-Bissau (West Africa).

We have retrospectively studied the seroprevalence of the human immunodeficiency virus (HIV) in Guinea-Bissau in a sample of sera collected from the whole country in 1980. We tested a total of 1248 individuals and found 11 individuals who were seropositive for HIV-2 but there were no HIV-1 seropositive samples. The mean age of the HIV-2 seropositive people was significantly higher than the age of the seronegative individuals. In the different areas surveyed, the HIV-2 seroprevalence ranged from 0 to 2.5%. A central region of the country, grossly centred in the capital city of Bissau, presented the highest prevalence of HIV-2 seropositivity (>2%), which contrasts with its virtual absence from the more remote rural areas located near the borders with the neighbouring countries. The overall seroprevalence found for HIV-2 in this study is 0.9% (1.8%, when considering the adult seroprevalence only), which proves that the virus was definitely circulating in Guinea-Bissau at the beginning of the 1980s.