Active Case Finding Strategies in Tuberculosis Control

Active case finding (ACF) encompasses proactive approaches to identify undiagnosed tuberculosis (TB) cases before individuals seek care. Strategies range from door-to-door symptom screening and mobile radiography to systematic contact tracing and digital chest X-ray with computer-aided detection. By targeting high-risk groups—people living with HIV, household contacts of infectious cases or residents of urban slums—ACF aims to interrupt transmission chains and accelerate treatment initiation. Recent innovations include integration of portable diagnostic tools, machine-learning-assisted image analysis and community health worker networks. The global significance of ACF lies in its potential to bridge gaps in passive detection, improve case notification rates and reduce TB prevalence. Optimal implementation requires high coverage, robust monitoring and context-specific adaptation to balance resource intensity with impact.

Research from Nature Portfolio

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Research from all publishers

Systematic reviews of community-based ACF interventions have concluded that programmes combining mobilisation, door-to-door sputum collection and decentralised diagnostics can increase case notifications and, in some settings, reduce TB prevalence when delivered with sufficient intensity. A large community-randomised trial in South Africa and Zambia found that symptom-based screening alone did not lower overall prevalence, highlighting the need for adjunctive chest radiography. In Uganda, two mass screening campaigns deployed village health teams for door-to-door symptom screening and rapid diagnostic testing, resulting in 13–16% of screened individuals meeting presumptive criteria and substantial increases in case notification rates. Together, these studies underscore that hybrid models—blending symptom questionnaires, chest X-ray and targeted molecular testing—are most effective when coupled with strong linkage to treatment services.

Active Case Finding Strategies in Tuberculosis Control publication trend

The graph below shows the total number of articles in active case finding strategies in tuberculosis control across all publications each year (not limited to Nature Index journals).

Technical terms

Active case finding (ACF): Proactive identification of TB cases through systematic screening of populations rather than waiting for symptomatic individuals to present for care.

Chest radiography (CXR): Imaging technique used to detect lung abnormalities; often employed alongside symptom screening to enhance TB detection sensitivity.

Sputum smear microscopy: Laboratory method that stains and examines expectorated sputum under a microscope to identify acid-fast bacilli indicative of TB.

Contact tracing: Process of identifying, screening and managing individuals who have been in close proximity to an infectious TB case.

Case notification rate: Number of newly detected TB cases reported to public health authorities per 100,000 population over a specified period.

Computer-aided detection (CAD): Software algorithms that analyse digital chest X-ray images to flag radiographic signs of TB, improving diagnostic throughput and consistency.

References

1. Tuberculosis prevalence after 4 years of population-wide systematic TB symptom screening and universal testing and treatment for HIV in the HPTN 071 (PopART) community-randomised trial in Zambia and South Africa: A cross-sectional survey (TREATS). PLOS Medicine (2023).
2. Community-based active case-finding interventions for tuberculosis: a systematic review. The Lancet Public Health (2021).
3. Community tuberculosis screening, testing and care, Uganda. Bulletin of the World Health Organization (2024).