HIV-1, HIV-2 and other Sexually Transmitted Infections in Guinea-Bissau, West Africa

Abstract: HIV-1 is dominating the global HIV pandemic, while HIV-2 is mainly confined to West Africa. The highest HIV-2 prevalence figures have been reported from Guinea-Bissau. While HIV-1 infection almost invariably leads to progressive immune dysfunction and AIDS, HIV-2 infection is characterised by a smaller proportion of individuals with disease progression to AIDS. In order to monitor the long-term epidemiological trends of HIV-1 and HIV-2, we performed sentinel studies among pregnant women and followed a cohort of police officers. During the period 1987 to 2004, HIV-2 prevalence declined from 8.3% to 1.5% in pregnant women and during 1990 to 2007, HIV-2 prevalence declined from 13.4% to 6.2% among police officers. We examined specifically if the civil war 1998 – 1999 had any impact on the HIV epidemic in Guinea-Bissau and found that HIV-1 prevalence among pregnant women increased sharply to 5.2% after the conflict but then stabilised around 5%. Among the police officers the HIV-1 prevalence pattern was the same. Also HIV-1 incidence peaked during and shortly after the conflict, but later stabilised at lower levels. Thus we noticed a short-term effect exerted by the war but we did not see any evidence of long-term effects that could be explained by the conflict. We examined the natural course of HIV-2 infection in seroincident individuals after 20 years of follow-up in the police cohort. As expected, median survival time and disease progression time to AIDS was longer and the CD4+ T cell decline rate was lower compared with HIV-1 infection. There was no significant difference compared with HIV-2 seroprevalent individuals, indicating that earlier studies of HIV-2 seroprevalent individuals were quite representative for HIV-2 infection in general. According to our data, a majority of HIV-2-infected individuals, if followed over longer time, will probably progress to immunodeficiency and clinical disease. Early loss of CD4+ T cells correlated to outcome, just as in HIV-1 infection. We also investigated the difference in disease course in seroincident HIV-1 infection and the influence of contemporaneous HIV-2 infection. The median time of progression to AIDS was 53% longer in dual HIV-1 and HIV-2 infection than in HIV-1 single infection and the difference was more pronounced in the individuals with a recorded HIV-2 infection preceding seroconversion to HIV-1. The epidemiological results correlated to higher CD4+ T cell counts and lower genetic HIV-1 diversity among the dually infected individuals compared with the HIV-1 single-infected. Finally, we investigated the prevalence of other STIs in women with urogenital problems and found high prevalence of several STIs. The most prevalent were Trichomonas vaginalis (20.4%) and Chlamydia trachomatis (12.6%). Infections with Herpes Simplex Virus type 2 and Mycoplasma genitalium were associated with HIV positivity.