Epidemiology, diagnosis and treatment of asymptomatic tuberculosis: an expert review

There is increasing evidence to suggest that a significant proportion of prevalent TB is asymptomatic (aTB). In recognition of the potential implications for disease elimination, the World Health Organization (WHO) formally included aTB within its case-definitions in 2024.

A literature review was conducted to guide discussions during the consultation for the revised definitions through a purposive synthesis of selected literature and input from experts to identify ongoing unpublished research. Three broad domains of relevance to asymptomatic TB were selected: (1) epidemiology; (2) diagnostics and (3) treatment.

The estimated proportion of prevalent TB that is asymptomatic varies from 27% to 82% depending on symptom thresholds. Emerging evidence suggests that aTB can be transmissible. Asymptomatic TB may be identified during community screening through digital chest X-rays and molecular testing, however, more sensitive diagnostics assays and alternative sampling approaches to sputum require development. Ongoing trials are investigating novel shorter course regimens for aTB.

Many critical knowledge gaps remain in our understanding of aTB. The revised definitions by WHO are expected to catalyze research in this area and support a coordinated effort to accelerate global disease elimination.