Mycobacterium tuberculosis transmission: the importance of precision

The identification of Mycobacterium tuberculosis as a causal agent of tuberculosis revolutionised the understanding of human diseases by showing that some have an infectious origin. How M tuberculosis spreads remained speculative until pioneering work—including having pulmonary tuberculosis patients cough directly onto guinea pigs—showed transfer of the bacillus to cause disease in a new host.1 This early link between symptomatic disease and cough-mediated M tuberculosis release established a concept that has informed tuberculosis science for decades—namely, that advanced lung pathology is a prerequisite for M tuberculosis transmission from a patient with tuberculosis.