Aerobiology and Transmission of Mycobacterium tuberculosis.

Despite vast changes in human social structures through evolution-from small hunter-gatherer bands to densely populated megacities-Mycobacterium tuberculosis (Mtb) has persisted within human populations for millennia, underscoring the bacterium's exceptional transmissibility. This paper examines the aerobiological foundations of Mtb transmission, tracing the bacillus from expulsion in respiratory aerosols through environmental survival to deposition and infection in new hosts. It considers how host, mycobacterial, and environmental factors interact to influence transmission efficiency, highlighting recent advances in direct aerosol sampling that have challenged longstanding assumptions. While cough has traditionally been considered the primary dissemination route, new evidence shows that tidal breathing can generate infectious aerosols in the absence of symptoms. These findings are consistent with emerging evidence suggesting that asymptomatic individuals may contribute more substantially to transmission than previously recognized, with significant implications for understanding Mtb pathogenicity and host susceptibility to infection and disease.