Tuberculosis Immunoreactivity Surveillance in Malawi (Timasamala)-A protocol for a cross-sectional Mycobacterium tuberculosis immunoreactivity survey in Blantyre, Malawi

PLoS One. 2024 May 24;19(5):e0291215. doi: 10.1371/journal.pone.0291215. eCollection 2024.

Abstract

Tuberculosis (TB) transmission and prevalence are dynamic over time, and heterogeneous within populations. Public health programmes therefore require up-to-date, accurate epidemiological data to appropriately allocate resources, target interventions, and track progress towards End TB goals. Current methods of TB surveillance often rely on case notifications, which are biased by access to healthcare, and TB disease prevalence surveys, which are highly resource-intensive, requiring many tens of thousands of people to be tested to identify high-risk groups or capture trends. Surveys of "latent TB infection", or immunoreactivity to Mycobacterium tuberculosis (Mtb), using tests such as interferon-gamma release assays (IGRAs) could provide a way to identify TB transmission hotspots, supplementing information from disease notifications, and with greater spatial and temporal resolution than is possible to achieve in disease prevalence surveys. This cross-sectional survey will investigate the prevalence of Mtb immunoreactivity amongst young children, adolescents and adults in Blantyre, Malawi, a high HIV-prevalence city in southern Africa. Through this study we will estimate the annual risk of TB infection (ARTI) in Blantyre and explore individual- and area-level risk factors for infection, as well as investigating geospatial heterogeneity of Mtb infection (and its determinants), and comparing these to the distribution of TB disease case-notifications. We will also evaluate novel diagnostics for Mtb infection (QIAreach QFT) and sampling methodologies (convenience sampling in healthcare settings and community sampling based on satellite imagery), which may increase the feasibility of measuring Mtb infection at large scale. The overall aim is to provide high-resolution epidemiological data and provide new insights into methodologies which may be used by TB programmes globally.

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Cross-Sectional Studies
  • Female
  • Humans
  • Interferon-gamma Release Tests / methods
  • Malawi / epidemiology
  • Male
  • Mycobacterium tuberculosis* / immunology
  • Prevalence
  • Risk Factors
  • Tuberculosis* / diagnosis
  • Tuberculosis* / epidemiology
  • Young Adult

Grants and funding

This work was supported by the Wellcome Trust [225482/Z/22/Z, 200901/Z/16/Z, 206575/Z/17/Z], and by the UK Foreign, Commonwealth and Development Office [“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 manufacturers of QFT-Plus and QIAreach QFT (QIAGEN) have agreed to provide tests at reduced or no cost for the purposes of research. The investigators will retain all control over research questions and design, data analysis and dissemination, and the manufacturer will play no role in study design, collection, analysis, and interpretation of data, or writing up the study findings.