---
title: "Targeting TB active case finding using Mtb immunoreactivity (ARTI) surveys in Blantyre, Malawi"
id: "plos-medicine-0-potential-health-impacts-and-costs-of-active-case-finding-guided-by"
canonical_url: "https://medichelpline.com/clinical-feed/plos-medicine-0-potential-health-impacts-and-costs-of-active-case-finding-guided-by"
content_type: "clinical_feed_article"
specialty: "Infectious Disease"
source_name: "PLOS Medicine"
source_url: "https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272"
published_at: "2026-10-07T14:00:00.000Z"
evidence_level: "Journal Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Targeting TB active case finding using Mtb immunoreactivity (ARTI) surveys in Blantyre, Malawi
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/plos-medicine-0-potential-health-impacts-and-costs-of-active-case-finding-guided-by
- **Specialty:** [Infectious Disease](https://medichelpline.com/clinical-feed/infectious-disease.md)
- **Primary Source:** PLOS Medicine
- **Source URL:** [Original Journal Publication](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272)
- **Published At:** 2026-10-07T14:00:00.000Z
- **Evidence Rating:** Journal Feed
## Executive GIST (TL;DR)
- This mathematical modelling study evaluated the potential health impact and costs of **active case finding (ACF)** for tuberculosis (TB) when geographically targeted using **Mycobacterium tuberculosis (Mtb) immunoreactivity** survey estimates of the annual risk of TB infection (**ARTI**) in children <5 years, compared with untargeted ACF and passive case finding (PCF) alone. - The model was parameterized with local data from 33 urban neighbourhoods in Blantyre, Malawi, and used a Markov microsimulation to estimate life expectancy, disability-adjusted life years (**DALYs**) and costs from health system and societal perspectives. - Targeted ACF covering half of the study population was estimated to identify 80% of all individuals with TB, achieving a lower cost per DALY averted (US$400, 95% CrI [20, 1,000]) than untargeted ACF (US$700, 95% CrI [100, 1,500]). - Compared with PCF-only, untargeted ACF improved life expectancy for individuals with TB by an estimated 3.3 years (95% CrI [1.7, 5.4]) but incurred higher costs. - In the main analysis, both ACF strategies produced incremental cost-effectiveness ratios that exceeded commonly used cost-effectiveness thresholds for Malawi; cost-effectiveness improved under assumptions of higher TB prevalence or greater reductions in transmission. - Key uncertainties and limitations include the assumed relationship between **ARTI** and true TB prevalence, transmission dynamics, and intervention effectiveness; these remain uncertain and affect projected impact and value for money. - The authors conclude that **ARTI-guided targeted ACF** could substantially improve efficiency and health impact versus untargeted approaches, but low-cost, scalable methods for collecting immunoreactivity data are needed for wider implementation and empirical evaluation is required.
## Clinical Analysis & Structured Key Points
[ Skip to main content ](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#main-content) Advertisement * [plos.org](https://plos.org/) * [Create account](https://community.plos.org/registration/new) * [Sign in](https://journals.plos.org/user/secure/login?page=%2Fplosmedicine%2Farticle%3Fid%3D10.1371%2Fjournal.pmed.1005272) * * About * Browse * Publish * [](https://journals.plos.org/plosmedicine/ "PLOS Medicine") * Search [advanced search](https://journals.plos.org/plosmedicine/search) * Loading metrics Open Access Peer-reviewed Research Article # Potential health impacts and costs of active case finding guided by _Mycobacterium tuberculosis_ immunoreactivity survey results in Blantyre, Malawi: A mathematical modeling study * Sun Kim , Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Writing – original draft, Writing – review & editing * E-mail: sunkim@alumni.harvard.edu Affiliation Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America [ ![ORCID logo](https://journals.plos.org/resource/img/orcid_16x16.png) https://orcid.org/0000-0002-2466-2442 ](https://orcid.org/0000-0002-2466-2442 "ORCID Registry") ⨯ * Melike Hazal Can, Roles Data curation, Formal analysis, Methodology, Writing – review & editing Affiliation Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America [ ![ORCID logo](https://journals.plos.org/resource/img/orcid_16x16.png) https://orcid.org/0000-0001-6810-0356 ](https://orcid.org/0000-0001-6810-0356 "ORCID Registry") ⨯ * Hannah M. Rickman, Roles Data curation, Resources, Writing – review & editing Affiliations Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom, Malawi Liverpool Wellcome Programme, Blantyre, Malawi [ ![ORCID logo](https://journals.plos.org/resource/img/orcid_16x16.png) https://orcid.org/0000-0002-3502-0744 ](https://orcid.org/0000-0002-3502-0744 "ORCID Registry") ⨯ * Mphatso D. Phiri, Roles Resources, Writing – review & editing Affiliations Malawi Liverpool Wellcome Programme, Blantyre, Malawi, Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom [ ![ORCID logo](https://journals.plos.org/resource/img/orcid_16x16.png) https://orcid.org/0000-0002-4072-9715 ](https://orcid.org/0000-0002-4072-9715 "ORCID Registry") ⨯ * Marriott Nliwasa, Roles Resources, Writing – review & editing Affiliation Helse Nord Tuberculosis Initiative, Department of Pathology, Kamuzu University of Health Sciences, Blantyre, Malawi [ ![ORCID logo](https://journals.plos.org/resource/img/orcid_16x16.png) https://orcid.org/0000-0002-3100-5512 ](https://orcid.org/0000-0002-3100-5512 "ORCID Registry") ⨯ * Tisungane E. Mwenyenkulu, Roles Resources, Writing – review & editing Affiliation National Tuberculosis and Leprosy Elimination Program, Ministry of Health, Lilongwe, Malawi ⨯ * Kuzani Mbendera, Roles Resources, Writing – review & editing Affiliation National Tuberculosis and Leprosy Elimination Program, Ministry of Health, Lilongwe, Malawi ⨯ * Stéphane Verguet, Roles Conceptualization, Supervision, Writing – review & editing Affiliation Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America [ ![ORCID logo](https://journals.plos.org/resource/img/orcid_16x16.png) https://orcid.org/0000-0003-4128-0849 ](https://orcid.org/0000-0003-4128-0849 "ORCID Registry") ⨯ * Marcia C. Castro, Roles Conceptualization, Supervision, Writing – review & editing Affiliation Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America [ ![ORCID logo](https://journals.plos.org/resource/img/orcid_16x16.png) https://orcid.org/0000-0003-4606-2795 ](https://orcid.org/0000-0003-4606-2795 "ORCID Registry") ⨯ * Elizabeth L. Corbett, Roles Funding acquisition, Resources, Writing – review & editing Affiliations Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom, Malawi Liverpool Wellcome Programme, Blantyre, Malawi [ ![ORCID logo](https://journals.plos.org/resource/img/orcid_16x16.png) https://orcid.org/0000-0002-3552-3181 ](https://orcid.org/0000-0002-3552-3181 "ORCID Registry") ⨯ * Peter MacPherson, Roles Conceptualization, Data curation, Funding acquisition, Investigation, Resources, Supervision, Validation, Writing – review & editing Affiliation School of Health & Wellbeing, University of Glasgow, Glasgow, United Kingdom [ ![ORCID logo](https://journals.plos.org/resource/img/orcid_16x16.png) https://orcid.org/0000-0002-0329-9613 ](https://orcid.org/0000-0002-0329-9613 "ORCID Registry") ⨯ * Ted Cohen, Roles Conceptualization, Funding acquisition, Investigation, Supervision, Validation, Writing – review & editing Affiliation Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America [ ![ORCID logo](https://journals.plos.org/resource/img/orcid_16x16.png) https://orcid.org/0000-0002-8091-7198 ](https://orcid.org/0000-0002-8091-7198 "ORCID Registry") ⨯ * Nicolas A. Menzies Roles Conceptualization, Funding acquisition, Investigation, Validation, Writing – review & editing Affiliation Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America [ ![ORCID logo](https://journals.plos.org/resource/img/orcid_16x16.png) https://orcid.org/0000-0002-2571-016X ](https://orcid.org/0000-0002-2571-016X "ORCID Registry") ⨯ # Potential health impacts and costs of active case finding guided by _Mycobacterium tuberculosis_ immunoreactivity survey results in Blantyre, Malawi: A mathematical modeling study * Sun Kim, * Melike Hazal Can, * Hannah M. Rickman, * Mphatso D. Phiri, * Marriott Nliwasa, * Tisungane E. Mwenyenkulu, * Kuzani Mbendera, … * Stéphane Verguet, * Marcia C. Castro, * Elizabeth L. Corbett ![PLOS](https://journals.plos.org/resource/img/logo-plos-full-color.svg) x * Published: October 7, 2026 * * [Article](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272) * [Authors](https://journals.plos.org/plosmedicine/article/authors?id=10.1371/journal.pmed.1005272) * [Metrics](https://journals.plos.org/plosmedicine/article/metrics?id=10.1371/journal.pmed.1005272) * [Comments](https://journals.plos.org/plosmedicine/article/comments?id=10.1371/journal.pmed.1005272) * [Media Coverage](http://plos.altmetric.com/details/doi/10.1371/journal.pmed.1005272) * [Peer Review](https://journals.plos.org/plosmedicine/article/peerReview?id=10.1371/journal.pmed.1005272) * [Abstract](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#abstract0) * [Author summary](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#abstract1) * [Introduction](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#sec007) * [Methods](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#sec008) * [Results](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#sec018) * [Discussion](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#sec026) * [Supporting information](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#sec027) * [Acknowledgments](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#ack) * [References](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#references) * [Reader Comments](https://journals.plos.org/plosmedicine/article/comments?id=10.1371/journal.pmed.1005272) * [Figures](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272) [?](https://journals.plos.org/plosmedicine/s/accepted-manuscripts#loc-early-version) ## This is an uncorrected proof. ## Abstract ### Background Active case finding (ACF) for tuberculosis (TB) can reduce transmission, yet efficient targeting requires high-quality surveillance data. We investigated the potential costs and impact of targeted ACF, guided by local estimates of the annual risk of TB infection (ARTI) derived from _Mycobacterium tuberculosis_ (_Mtb_) immunoreactivity survey data in children aged and are archived with a citable identifier (DOI: ). **Funding:** HMR was funded by Wellcome (225482/Z/22/Z). PM was funded by Wellcome (304666/Z/23/Z, ) and an NIHR Global Health Research Professorship (NIHR304311, ). TC was funded by NIAID (R01AI147854, ). This work was funded by the UK aid from the UK government [to MDP, ELC, and PM; “Leaving no-one behind: transforming gendered pathways to health for TB”; (2018/S 196-443482, ]; however, the views expressed do not necessarily reflect the UK government’s official policies. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. **Competing interests:** I have read the journal’s policy and the authors of this manuscript have the following competing interests: PM is an Academic Editor on PLOS Medicine’s editorial board. EC was a Guest Editor on PLOS Medicine. All other authors declare that no competing interests exist. **Abbreviations:** ACF, Active case finding; AI, Artificial Intelligence; ARTI, annual risk of TB infection; CrI, credible interval; DALY, disability-adjusted life year; ICERs, incremental cost-effectiveness ratios; IGRAs, interferon-gamma release assays; LE, life expectancies; NTLEP, National Tuberculosis and Leprosy Elimination Program; PCF, passive case finding; YLDs, years lived with disability; YLLs, years of life lost ## Introduction Tuberculosis (TB) remains a major global public health threat, especially in regions with a high burden of HIV [[1](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#pmed.1005272.ref001)]. Active case finding (ACF) is recommended by the World Health Organization to identify individuals with untreated TB, and involves offering systematic screening to community members regardless of symptoms. ACF can be effective in reducing the prevalence of undiagnosed infectious TB, and therefore interrupting community transmission [[2](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#pmed.1005272.ref002)]. While it holds promise, untargeted implementation across entire populations may be expensive and inefficient. Targeting ACF to high-prevalence areas may increase efficiency; however, data to identify such areas (e.g., subnational TB prevalence surveys) are usually not available due to the cost and large sample sizes required to conduct such surveys [[3](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#pmed.1005272.ref003)]. TB case notification data could be used as a proxy for prevalence to guide ACF targeting, but areas with high notification rates may reflect capacity for prompt care-seeking behavior and better access to health services, rather than underlying disease burden. New approaches to prioritizing communities with a high burden of undiagnosed disease are required, especially in the context of declining TB burdens [[4](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#pmed.1005272.ref004)]. Malawi is a low-income country in southeastern Africa, with TB incidence of 119 per 100,000 and nearly half of all cases occurring among persons with HIV [[1](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#pmed.1005272.ref001)]. In Blantyre, the second most populous city in the country, high TB notification rates are frequently observed in better-resourced neighborhoods with stronger health infrastructure, potentially obscuring areas with high levels of undiagnosed TB [[4](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#pmed.1005272.ref004),[5](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#pmed.1005272.ref005)]. Like many high TB burden countries, Malawi’s National Tuberculosis and Leprosy Elimination Program (NTLEP) undertakes ACF, including community-based door-to-door outreach and mobile van-based diagnostic units equipped with Xpert and digital chest X-ray [[6](https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005272#pmed.1005272.ref006)]. But determining which commu
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