Population-wide active case finding as a strategy to end TB

Abstract

Tuberculosis (TB) is the leading infectious cause of morbidity and mortality globally. Despite available tools for preventing, finding, and treating TB, many people with TB remain undiagnosed. In high-incidence settings, TB transmission is ubiquitous within the community, affecting both high-risk groups and the general population. In fact, most people who develop TB come from the general population. To disrupt the chain of transmission that sustains the TB epidemic, we need to find and treat everyone with infectious TB as early as possible, including those with minimal symptoms or subclinical TB who are unlikely to present for care. Important elements of an effective active case-finding strategy include effective social mobilisation and community engagement, using sensitive screening tools that can be used at scale, and embracing population-wide screening in high-incidence ('hot spot') areas. We require a better description of feasible delivery models, 'real-life' impact and cost effectiveness to enable wider implementation.

Keywords: High-incidence settings; Population-wide active case finding; Tuberculosis.

Fig. 1

Barriers to the diagnosis and effective treatment of people with infectious TB in the community. The left column represents the five levels of the socio-ecological framework. The top row represents the steps in the TB care cascade. Abbreviation: TB; tuberculosis.

Fig. 2

Relevant risk factors and interventions to consider along the ‘TB triangle’. The figure shows the risk factors (black boxes) and interventions for TB (purple boxes) at different phases of TB infection and disease. Abbreviation: TB; tuberculosis.

Fig. 3

The population impact of targeted screening vs population-wide screening for TB disease. This figure illustrates the potential impact of targeted and population-wide screening for TB disease. Boxes A represent hypothetical scenarios in high-incidence settings where TB disease is not confined to at-risk groups. Boxes B represent the scope and reach of targeted screening (green circle) and population-wide screening (yellow circle). Boxes C represent the potential impact of the different screening approaches. The number of smaller circles does not accurately reflect the population size or the precise transmission risk resulting from the different screening methods deployed. Abbreviation: TB; tuberculosis.