LATENT TUBERCULOSIS AMONG ADULT ETHIOPIAN PATIENTS AT CHEST CLINIC, TIKURANBESSA SPECIALIZED HOSPITAL, ADDIS ABABA, ETHIOPIA.

Background: One-third of the world population is infected with Mycobacterium tuberculosis. Most people exposed to M. tuberculosis showed no evidence of active disease. About 5-10% of people with latent tuberculosis infection (LTBI) without HIV will progress to develop active tuberculosis (TB) 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 (TST) 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 LTBI using Quantiferon Gold, 45(64%) tested positive and 25 (36%) were negative for latent tuberculosis infection. From the 66 healthy individuals who were tested using TST for LTBI, 42 (62%) individuals were TST positive and 25 (38%) individuals were TST 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 TB. TST and Quantiferon-Tuberculosis-Gold assay show similar efficacy for the diagnosis of LTBI in healthy Ethiopian adults. The absolute CD4 T-cell counts of healthy HIV- negative Ethiopians are considerably lower than CD4 T cell counts in other countries.