A SYSTEMATIC REVIEW: ENVIRONMENTAL OCCURRENCE OF MYCOBACTERIUM TUBERCULOSIS AND ITS ASSOCIATED RISK OF TUBERCULOSIS INFECTION AND DISEASE

Tuberculosis (TB) remains a major public health concern, primarily caused by Mycobacterium tuberculosis and transmitted through the air. Although airborne transmission is well established, the occurrence of the bacterium in different environmental settings and its possible contribution to exposure and infection remain incompletely understood. This systematic review aimed to examine the environmental occurrence of M. tuberculosis and the M. tuberculosis complex (MTBC), identify the methods used for detection, and evaluate the evidence linking environmental occurrence to potential exposure, TB infection, and disease. Ten studies, consisting of seven primary studies and three reviews, were examined. The included studies covered healthcare facilities, schools, households, prison cells, public transportation, soil, and wastewater across South Africa, Indonesia, Brazil, discussed in global reviews. Detection methods included air filtration, surface sampling, polymerase chain reaction (PCR), droplet digital PCR (ddPCR), GeneXpert, DNA sequencing, and culture-based techniques. Findings indicated that MTBC DNA was detected in several environmental samples, including indoor air and surfaces in settings associated with potential exposure. Environmental conditions such as poor ventilation and overcrowding were also identified as factors that may increase transmission risk. However, six of the seven primary studies relied on DNA-based detection, which cannot confirm bacterial viability or prove environmental transmission to humans. The findings suggest that environmental monitoring may help identify locations with potential TB exposure risks. Further research using standardized sampling methods and bacterial viability testing is needed to clarify the role of environmental occurrence in TB transmission and inform effective prevention strategies.