Cohort Profile: The Bissau HIV Cohort-a cohort of HIV-1, HIV-2 and co-infected patients.

The West African country Guinea-Bissau is home to the world's highest prevalence of HIV-2, and its HIV-1 prevalence is rising. Other chronic viral infections like human T-lymphotropic virus type 1 (HTLV-1) and hepatitis B virus are common as well. The Bissau HIV Cohort was started in 2007 to gain new insights into the overall effect of introducing antiretroviral treatment in a treatment-naïve population with concomitant infection with three retroviruses (HIV-1, HIV-2 and HTLV-1) and tuberculosis. The cohort includes patients from the HIV clinic at Hospital Nacional Simão Mendes, the main hospital in Bissau, the capital of the country. From July 2007 to June 2013, 3762 HIV-infected patients (69% HIV-1, 18% HIV-2, 11% HIV-1/2 and 2% HIV type unknown) were included in the world's largest single-centre HIV-2 cohort. Demographic and clinical data are collected at baseline and every 6 months, together with CD4 cell count and routine biochemistry analyses. Plasma and cells are stored in a biobank in Denmark. The Bissau HIV Cohort is administered by the Bissau HIV Cohort study group. Potential collaborators are invited to contact the chair of the cohort study group, Christian Wejse, e-mail: [wejse@dadlnet.dk].