ABSTRACT
Background: One-third of the world population is infected with mycobacterium tuberculosis. Most people exposed to mycobacterium tuberculosis showed no evidence of active disease. About 5-10% of latent tuberculosis infection without HIV will progress to developed active tuberculosis in their lifetimes. This study was conducted to determine the magnitude of Latent TB among the adult population at a teaching and referral Hospital in Ethiopia.Methods: This study was conducted at the Chest clinic of Tikur Anbessa Specialized Hospital during 2010-2013.The study was a cross-sectional study conducted among healthy adults after informed consent was obtained from each individual. Tuberculin skin test and Interferon Gamma whole blood assay (Quantiferon-Tuberculosis-Gold) was performed using Enzyme linked Immuno-sorbent Assay. Average CD4, CD8, CD3 and CD4:CD8 ratio was determined for all study participants. Results:From a total of 70 healthy adults tested for latent tuberculosis infection using Quantiferon Gold,45(64%) tested positive and 25 (36%) were negative for latent tuberculosis infection. From the sixty six healthy individuals who were tested using tuberculin skin test for latent tuberculosis infection, 42 (62%) individuals were Tuberculin skin test positive and 25 (38%) individuals were Tuberculin skin test negative. Average CD4, CD8, CD3 and CD4:CD8 ratio was 748, 598, 1401 and 1.4, respectively. Conclusions: The magnitude of latent tuberculosis infection was high in this study, which reflects existing high prevalence of tuberculosis.Tuberculin skin test and Quantiferon-Tuberculosis-Goldassay show similar efficacy for the diagnosis of latent tuberculosis infection in healthy Ethiopian adults. The absolute CD4 T-cell counts of healthy HIV-negative Ethiopian's are considerably lower than other countries