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Abstract Background One third of the world’s population is thought to have latent tuberculosis infection (LTBI) with the potential for subsequent reactivation of disease. To better characterize this important population, studies comparing Tuberculin Skin Test (TST) and the new interferon-γ release assays including QuantiFERON®-TB Gold In-Tube (QFT-GIT) have been conducted in different parts of the world, but most of these have been in countries with a low incidence of tuberculosis (TB). The aim of this study was therefore to evaluate the use of QFT-GIT assay as compared with TST in the diagnosis of LTBI in Ethiopia, a country with a high burden of TB and routine BCG vaccination at birth. Methods Healthy medical and paramedical male students at the Faculty of Medicine, Addis Ababa University, Ethiopia were enrolled into the study from December 2008 to February 2009. The TST and QFTG-IT assay were performed using standard methods. Results The mean age of the study participants was 20.9 years. From a total of 107 study participants, 46.7% (95%CI: 37.0% to 56.6%) had a positive TST result (TST≥10 mm), 43.9% (95%CI: 34.3% to 53.9%) had a positive QFT-GIT assay result and 44.9% (95%CI: 35.2% to 54.8%) had BCG scar. There was strong agreement between TST (TST ≥10mm) and QFT-GIT assay (Kappa = 0.83, p value = 0.000). Conclusion The TST and QFT-GIT assay show similar efficacy for the diagnosis of LTBI in healthy young adults residing in Ethiopia, a country with high TB incidence.

Abstract Background Healthcare wastes contain a wide range of microorganisms among which hepatitis B virus (HBV) are the most significant pathogens. No data about the prevalence of HBV among medical waste handlers is available in Addis Ababa, Ethiopia. Therefore; this study was conducted to describe the prevalence of HBV infection among medical waste handlers in Government hospitals of Addis Ababa, Ethiopia. Findings A cross sectional study was conducted among 252 medical and non-medical waste handlers working in three Government hospitals of Addis Ababa between May to July, 2010. Predesigned and tested questionnaire was used to collect soiociodemographic information. Blood sample was taken from 252 waste handlers and serum was tested for Hepatitis B surface antigen (HBsAg) and anti-Hepatitis core antigen (anti-HBcAg) using Enzyme Linked Immuno Sorbent Assay. Of the 126 Medical Waste Handlers and 126 Non Medical Waste Handler, HBsAg was detected in 8 (6.3%) and 1 (0.8%), and anti-HBcAg in 60 (47.6%) and 40 (31.7%), respectively. Significant differences were observed in the detection rates of HBsAg (OR: 8, 95% CI: 1.02, 63.02; p = 0.01), Anti-HB c Ag (OR: 1.5, 95% CI: 1.1, 2.1; p = 0.01) and either markers (OR: 1.7, 95% CI: 1.2, 2.2; p = 0.001) in medical waste handlers compared to non medical waste handlers. 19.8% were trained to handle medical waste and none was immunized against HBV. Conclusion This study shows a high prevalence of HBV infection in medical waste handlers compared to non medical waste handlers. Lack of training on how to handle medical waste among medical waste handlers was high.

Abstract Background Dendritic cells (DCs) can take up an array of different antigens, including microorganisms which they can process and present more effectively than any other antigen presenting cell. However, whether the interaction between the human DC and Mycobacterium tuberculosis represents a defense mechanism by the invaded host, or helping the invader to evade the defense mechanism of the host is still not clearly understood. Findings To analyze the interactions between M. tuberculosis and immune cells, human peripheral blood monocyte-derived immature DCs were infected with M. tuberculosis H37Rv wild type strain and flow cytometry was used to analyse cell surface expression markers. The ability of the M. tuberculosis infected DC to induce T cell proliferation using 5 and 6-carboxyfluorescein diacetate succinimidyl ester (CFSE) dilution technique was also investigated. DCs were found to internalize the mycobacteria and show dose dependent infection and necrosis with different multiplicity of infection. Flow cytometry analysis of cell surface expression markers CD40, CD54, CD80, CD83, CD86 and HLA DR in infected DC revealed significant (p < 0.05) up regulation following infection with M. tuberculosis in comparison to immature DC with no stimulation. Lipopolysaccharide (LPS) from Salmonella abortus equi, a known DC maturation agent, was used as a positive control and showed a comparable up regulation of cell surface markers as observed with M. tuberculosis infected DC. It was revealed that the M. tuberculosis infected DC induced T cell proliferation. Conclusion These data clearly demonstrate that M. tuberculosis induces activation and maturation of human monocyte-derived immature DC as well as induces T cell proliferation in vitro.