Active case finding for tuberculosis

Active Case Finding (ACF) is an effective strategy for early tuberculosis (TB) diagnosis through systematic screening, helping identify undetected cases and initiate prompt treatment. It plays a key role in reducing TB transmission and complements existing detection and treatment strategies, particularly among high-risk groups such as migrants, the homeless, prisoners, and the poor. ACF has been more effective in these populations than in the general public and requires consistent follow-up to ensure successful outcomes. The World Health Organization (WHO) recommends contact screening by healthcare workers, and when adequate resources are available, migrant communities can be successfully engaged in latent TB infection (LTBI) screening and treatment programs.[1]

Despite advancements in tuberculosis (TB) diagnostics, around 4 million people—nearly 40% of TB cases—remain undiagnosed or unreported worldwide. Most of these individuals live in periurban informal settlements in major cities across Africa and Asia, where they contribute to ongoing transmission of both drug-sensitive and drug-resistant TB strains. Addressing this gap is critical for TB control. Community-based Active Case Finding (ACF), where healthcare workers proactively screen populations for TB, has been shown to significantly reduce transmission, disease burden, and mortality compared to passive case finding, which often identifies cases only after substantial community spread has occurred.[2]

Various ACF strategies have been implemented in high-prevalence settings, including door-to-door screening, mobile unit outreach, and targeted screening of high-risk groups. Door-to-door approaches, particularly those using molecular diagnostic tools like the Cepheid GeneXpert system, have positively impacted community disease burden but are labor-intensive and costly. Mobile clinics have proven more efficient, and innovative, low-cost solutions such as mini-mobile clinics using portable, battery-operated Xpert systems (e.g., the XACT model) show promise. These point-of-care strategies detect more TB cases earlier, especially among those unlikely to self-report, and significantly shorten the time to treatment initiation. As a scalable and effective intervention, mobile point-of-care ACF strategies offer a practical solution to reducing the global burden of undiagnosed TB.[2]

Migrant populations face higher TB incidence rates compared to local populations, as observed in countries like Taiwan, China, and Denmark. Factors such as legal status, financial barriers, limited knowledge of TB symptoms, high mobility, and social isolation contribute to difficulties in accessing treatment and adhering to care. Studies show that population movement from high TB-burden countries increases TB incidence in low-burden regions, including Germany, Italy, Norway, and the United States. Community-based approaches, including integrated support services and symptom screening followed by laboratory testing, can help overcome these barriers. While ACF demonstrates clear benefits in targeted high-risk groups, evidence of its effectiveness in general populations within developing countries remains limited.[1]

Reference:

1. Pramono, J.S., Ridwan, A., Maria, I.L., Syam, A., Russeng, S.S. and Mumang, A.A., 2024. Active case finding for tuberculosis in migrants: a systematic review. Medical Archives, 78(1), p.60.

2. Esmail, A., Randall, P., Oelofse, S. et al. Comparison of two diagnostic intervention packages for community-based active case finding for tuberculosis: an open-label randomized controlled trial. Nat Med 29, 1009–1016 (2023).