Prevalence of the human immunodeficiency virus among patients with tuberculosis in Sierra Leone, established from dried blood spots on filter paper

SETTING: Sierra Leone National Tuberculosis Programme. OBJECTIVE: To evaluate serological testing in field conditions of dried blood spots (DBS) on filter paper for unlinked surveillance of human immunodeficiency virus (HIV) associated tuberculosis. DESIGN: DBS were first evaluated against sera in 359 consenting patients on the capital city's District Tuberculosis Register (DTR). DBS eluates were tested with repeated ELISA using different antigens. Serum samples were tested with ELISA and confirmed with LIA. The cost was compared with that of rapid/simple tests on whole blood. In a second phase, DBS were applied to an unlinked countrywide serosurvey of 582 patients from the DTRs. RESULTS: The specificity of DBS for HIV-1 and HIV-2 was 100% and sensitivity was 100% and 87.5%, respectively. The cost of the strategy was half that of rapid/simple tests on whole blood. In 1995, HIV-1 associated tuberculosis seroprevalence was 2.41%. CONCLUSION: The proposed method for the surveillance of HIV-1 associated tuberculosis in Africa is simple, cheap and accurate. Further investigations are necessary to evaluate its sensitivity for HIV-2, and to study the epidemiology of HIV-2 in Sierra Leone.