Sociological variety and the transmission efficiency ofMycobacterium tuberculosis: a secondary analysis of qualitative and quantitative data from 15 communities in Zambia

Abstract

ObjectivesSelected Zambian communities formed part of a cluster randomised trial: the Zambia and South Africa TB and AIDS Reduction study (ZAMSTAR). There was wide variability in the prevalence of Mycobacterium tuberculosis infection and tuberculosis (TB) disease across these communities. We sought to clarify whether specific communities could have been more/less vulnerable to M. tuberculosis transmission as a result of sociological variety relevant to transmission efficiency.DesignWe conducted a mixed methods secondary analysis using existing data sets. First, we analysed qualitative data to categorise and synthesise patterns of socio-spatial engagement across communities. Second, we compared emergent sociological variables with a measure of transmission efficiency: the ratio of the annual risk of infection to TB prevalence.SettingZAMSTAR communities in urban and peri-urban Zambia, spanning five provinces.ParticipantsFifteen communities, each served by a health facility offering TB treatment to a population of at least 25 000. TB notification rates were at least 400 per 100 000 per annum and HIV seroprevalence was estimated to be high.ResultsCrowding, movement, livelihoods and participation in recreational activity differed across communities. Based on 12 socio-spatial indicators, communities were qualitatively classified as more/less spatially crowded and as more/less socially ‘open’ to contact with others, with implications for the presumptive risk of M. tuberculosis transmission. For example, watching video shows in poorly ventilated structures posed a presumptive risk in more socially open communities, while outdoor farming and/or fishing were particularly widespread in communities with lower transmission measures.ConclusionsA dual dynamic of ‘social permeability’ and crowding appeared relevant to disparities in M. tuberculosis transmission efficiency. To reduce transmission, certain socio-spatial aspects could be adjusted (eg, increasing ventilation on transport), while more structural aspects are less malleable (eg, reliance on public transport). We recommend integrating community level typologies with genome sequencing techniques to further explore the significance of ‘social permeability’.Trial registration numberISRCTN36729271.

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“…Another explanatory route may be related to resilience 32 and that it has a direct relationship between its levels and positive health conditions 33 . The social permeability that captures the "mix" between ages and genders and patterns of traveling locals 34 it may be another figuration. Another hypothetical mechanism may be immunity compressed by prolonged exposure to psychosocial stress that induces physiological wear and tear and leads to decreased immune function 35 .…”

Community and health systems factors contributing to delayed tuberculosis detection in an urban setting: situating software and hardware bottlenecks in local health systems

“…Understanding how health systems and community levels factors interact to in uence delays in TB detection is critical because early diagnosis and prompt initiation on treatment are essential for the effectiveness of TB programs [16]. Additionally, in settings such as Zambia, most of the TB transmission occurs within community settings [17]. Hence, community health systems are of growing interest based on their potential to leverage community resources to generate and sustain demand for TB interventions [18].…”