Surrogate Immunological Markers of Infection and Progression to overt Mycobacterial Disease in Latent Tuberculosis Infection (LTBI)

Abstract

Tuberculosis (TB) is a major cause of morbidity and mortality worldwide, with grave economic consequences. Detection of patients with latent Mycobacterium tuberculosis infection (LTBI) is an important step towards the goal of tuberculosis elimination, because it improves case detection rates in developing countries. Household contacts (HHCs) of patients with active pulmonary TB are at high risk of infection and swift disease development. Tuberculin skin test (TST) is a cheap, simple and reasonably sensitive test of latent TB infections compared to whole blood IFN- ? levels assays Measurement of IL-4 mRNA and IL-4d 2 mRNA copies in healthy TB contacts is believed to be crucial for prediction of LTBI progression. This study aimed to define surrogate markers of infection and progression to overt tuberculosis among patients with latent tuberculosis infection. This was a prospective, longitudinal and community-based study, with 29 months duration, follow up for all volunteers in day 400. Following informed consent 98 HHCs and 186 community contacts (CCs) were enrolled in this study.