Publications by authors named "Karat A"

Identifying case-finding strategies to reduce tuberculosis (TB) incidence in high-burden countries requires better knowledge of the disease burden in key contributing populations and settings. To inform South Africa's National Tuberculosis Strategic Plan 2023-2028, we conducted a systematic review of active TB disease and latent TB infection (LTBI) prevalence and incidence in underserved populations, defined as those living in informal settlements, townships, or impoverished communities. We identified articles published from January 2010 to December 2023, assessed study quality, and conducted a meta-analysis to estimate pooled TB and LTBI prevalence stratified by HIV status.

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Tuberculosis infection prevention and control (TB IPC) measures are a cornerstone of policy, but measures are diverse and variably implemented. Limited attention has been paid to the health system environment, which influences successful implementation of these measures. We used qualitative system dynamics and group-model-building methods to (1) develop a qualitative causal map of the interlinked drivers of Mycobacterium tuberculosis (Mtb) transmission in South African primary healthcare facilities, which in turn helped us to (2) identify plausible IPC interventions to reduce risk of transmission.

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In India, the incidence of mucormycosis reached high levels during 2021-2022, coinciding with the COVID-19 pandemic. In response to this, we established a multicentric ambispective cohort of patients hospitalised with mucormycosis across India. In this paper, we report their baseline profile, clinical characteristics and outcomes at discharge.

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Article Synopsis
  • Airborne pathogens like Mycobacterium tuberculosis in healthcare settings pose significant risks to both health workers and patients, particularly in South Africa where a 3-year project revealed critical issues in tuberculosis infection prevention and control (TB-IPC).
  • Key findings highlight problems such as fragmented policies, clinic congestion, and inadequate facility designs that hinder effective TB-IPC interventions, with modeling studies demonstrating their economic viability in addressing tuberculosis burdens.
  • The report advocates for improved coordination in policymaking, better clinic designs, budget allocations for TB-IPC implementation, and further research to enhance screening methods and patient management strategies in primary healthcare clinics.
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Background: There are limited data on the performance characteristics of ultrasound for the diagnosis of pulmonary tuberculosis in both HIV-positive and HIV-negative persons. The objective of this proof-of-concept study was to determine the sensitivity and specificity of ultrasound for the diagnosis of tuberculosis in adults.

Methods: Comprehensive thoracic and focused abdominal ultrasound examinations were performed by trained radiologists and pulmonologists on adults recruited from a community multimorbidity survey and a primary healthcare clinic in KwaZulu-Natal Province, South Africa.

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Healthcare facilities are important sites for the transmission of pathogens spread via bioaerosols, such as Mycobacterium tuberculosis. Natural ventilation can play an important role in reducing this transmission. We aimed to measure rates of natural ventilation in clinics in KwaZulu-Natal and Western Cape provinces, South Africa, then use these measurements to estimate Mycobacterium tuberculosis transmission risk.

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Transmission of respiratory pathogens, such as Mycobacterium tuberculosis and severe acute respiratory syndrome coronavirus 2, is more likely during close, prolonged contact and when sharing a poorly ventilated space. Reducing overcrowding of health facilities is a recognised infection prevention and control (IPC) strategy; reliable estimates of waiting times and 'patient flow' would help guide implementation. As part of the Umoya omuhle study, we aimed to estimate clinic visit duration, time spent indoors versus outdoors, and occupancy density of waiting rooms in clinics in KwaZulu-Natal (KZN) and Western Cape (WC), South Africa.

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Background: Individuals with advanced HIV experience high mortality, especially before and during the first months of antiretroviral therapy (ART). We aimed to identify factors, measurable in routine, primary health clinic-based services, associated with the greatest risk of poor outcome.

Methods: We included all individuals enrolled in the standard-of-care arm of a cluster-randomized trial (TB Fast Track); adults attending participating health clinics with CD4 ≤150 cells/µL and no recent ART were eligible.

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Background: There is a high risk of () transmission in healthcare facilities in high burden settings. WHO guidelines on tuberculosis (TB) infection prevention and control (IPC) recommend a range of measures to reduce transmission in healthcare settings. These were evaluated primarily based on evidence for their effects on transmission to healthcare workers in hospitals.

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Article Synopsis
  • Health system constraints significantly impact the effectiveness and scalability of disease control interventions, requiring additional costs for enabling activities that should be factored into priority setting.
  • The study utilized group model building to gather insights from stakeholders about tuberculosis control constraints in South African primary healthcare clinics, informing the design of feasible interventions.
  • Cost analysis showed retrofitting for ventilation was the cheapest intervention, while staff training and improved information flow were identified as critical enablers, although some constraints could not be easily quantified.
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Background: Tuberculosis (TB) case finding efforts typically target symptomatic people attending health facilities. We compared the prevalence of Mycobacterium tuberculosis (Mtb) sputum culture-positivity among adult clinic attendees in rural South Africa with a concurrent, community-based estimate from the surrounding demographic surveillance area (DSA).

Methods: Clinic: Randomly selected adults (≥18 years) attending 2 primary healthcare clinics were interviewed and requested to give sputum for mycobacterial culture.

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Summary: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is transmitted mainly by aerosol in particles <10 µm that can remain suspended for hours before being inhaled. Because particulate filtering facepiece respirators ('respirators'; e.g.

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Background: Elevated rates of tuberculosis in healthcare workers demonstrate the high rate of ) transmission in health facilities in high-burden settings. In the context of a project taking a whole systems approach to tuberculosis infection prevention and control (IPC), we aimed to evaluate the potential impact of conventional and novel IPC measures on transmission to patients and other clinic attendees.

Methods: An individual-based model of patient movements through clinics, ventilation in waiting areas, and transmission was developed, and parameterised using empirical data from eight clinics in two provinces in South Africa.

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Tuberculosis (TB) remains the leading cause of hospitalization and in-hospital mortality in HIV-positive adults. Using data from hospital and clinic files, research databases, and autopsy, we describe causes and outcomes of admissions, and assess investigations for TB among adults with advanced HIV who were hospitalized after enrollment into the TB Fast Track trial in South Africa (2013-2015). A total of 251 adults [median CD4 count, 37.

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Although tuberculosis (TB) incidence has significantly declined in high-income, low-incidence (HILI) countries, challenges remain in managing TB in vulnerable populations who may struggle to stay on anti-TB treatment (ATT). Factors associated with non-adherence to ATT are well documented; however, adherence is often narrowly conceived as a fixed binary variable that places emphasis on individual agency and the act of taking medicines, rather than on the demands of being on treatment more broadly. Further, the mechanisms through which documented factors act upon the experience of being on treatment are poorly understood.

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Article Synopsis
  • * Researchers tested two methods to estimate absolute ventilation rates in variable-occupancy rooms using carbon dioxide measurements and head counts from a primary healthcare clinic.
  • * Both methods yielded similar results for ventilation rates, with the simpler linear regression being preferred because it does not require room volume measurements, aiding in efforts to improve air quality and reduce pathogen transmission.
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Improving adherence to anti-TB treatment is a public health priority in high-income, low incidence (HILI) regions. We conducted a scoping review to identify reported determinants of non-adherence in HILI settings. Key terms related to TB, treatment and adherence were used to search MEDLINE, EMBASE, Web of Science, PsycINFO and CINAHL in June 2019.

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Article Synopsis
  • Tuberculosis (TB) mortality in South Africa is a critical public health issue, with systemic drivers being less understood compared to direct causes; a systems thinking approach was used to identify and illustrate these factors through a causal loop diagram.
  • Identified key variables included three 'drivers' (adequacy of tools, guideline implementation, burden of bureaucracy), three 'links' (health service integration, data system integration, prevention strategy utilization), and three 'outcomes' (service accessibility, patient empowerment, socio-economic status).
  • The causal loop diagram revealed three reinforcing loops: one highlighting the impact of leadership on service accessibility and mortality, another showing the relationship between socio-economic factors and prevention strategies, and the last illustrating how fragmented leadership affects service performance and accessibility.
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Background: Two weeks' isolation is widely recommended for people commencing treatment for pulmonary tuberculosis (TB). The evidence that this corresponds to clearance of potentially infectious tuberculous mycobacteria in sputum is not well established. This World Health Organization-commissioned review investigated sputum sterilisation dynamics during TB treatment.

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Maintaining adherence to treatment for tuberculosis (TB) is essential if the disease is to be eliminated. As part of formative research to develop an intervention to improve adherence, we documented the lived experiences of adults receiving anti-TB treatment (ATT) in three UK cities and examined how personal, social, and structural circumstances interacted to impact on individuals' adherence to treatment. Using a topic guide that explored social circumstances and experiences of TB care, we conducted in-depth interviews with 18 adults (six women) who were being or had been treated for TB () and four adults (all women) who were caring for a friend, relative, or partner being treated for TB ().

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Background: We aimed to estimate the prevalence of and explore risk factors for infection among adolescents in a high tuberculosis (TB) and human immunodeficiency virus (HIV) prevalence setting.

Methods: A cross-sectional study of adolescents (10-19 years) randomly selected from a demographic surveillance area (DSA) in rural KwaZulu-Natal, South Africa. We determined infection status using the QuantiFERON-TB Gold-plus assay.

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Adherence to treatment for tuberculosis (TB) has been a concern for many decades, resulting in the World Health Organization's recommendation of the direct observation of treatment in the 1990s. Recent advances in digital adherence technologies (DATs) have renewed discussion on how to best address nonadherence, as well as offering important information on dose-by-dose adherence patterns and their variability between countries and settings. Previous studies have largely focussed on percentage thresholds to delineate sufficient adherence, but this is misleading and limited, given the complex and dynamic nature of adherence over the treatment course.

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Evidence is limited for infection prevention and control (IPC) measures reducing Mycobacterium tuberculosis (MTB) transmission in health facilities. This systematic review, 1 of 7 commissioned by the World Health Organization to inform the 2019 update of global tuberculosis (TB) IPC guidelines, asked: do triage and/or isolation and/or effective treatment of TB disease reduce MTB transmission in healthcare settings? Of 25 included articles, 19 reported latent TB infection (LTBI) incidence in healthcare workers (HCWs; absolute risk reductions 1%-21%); 5 reported TB disease incidence in HCWs (no/slight [high TB burden] or moderate [low burden] reduction) and 2 in human immunodeficiency virus-positive in-patients (6%-29% reduction). In total, 23/25 studies implemented multiple IPC measures; effects of individual measures could not be disaggregated.

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