Browsing by Subject "Environmental health"

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    Open Access
    Modes of transmission and attack rates of group A Streptococcal infection: a protocol for a systematic review and meta-analysis
    (2021-03-31) Barth, Dylan D; Daw, Jessica; Xu, Ruomei; Enkel, Stephanie; Pickering, Janessa; McRae, Tracy; Engel, Mark E; Carapetis, Jonathan; Wyber, Rosemary; Bowen, Asha C
    Background Group A Streptococcus (Strep A) is an important cause of mortality and morbidity globally. This bacterium is responsible for a range of different infections and post-infectious sequelae. Summarising the current knowledge of Strep A transmission to humans will address gaps in the evidence and inform prevention and control strategies. The objective of this study is to evaluate the modes of transmission and attack rates of group A streptococcal infection in human populations. Methods This systematic review protocol was prepared according to the Preferred Reporting Items for Systematic reviews and Meta-analysis Protocols (PRISMA-P) 2015 Statement. Using a comprehensive search strategy to identify any transmission studies that have been published in English since 1980, full-text articles will be identified and considered for inclusion against predefined criteria. We will include all studies reporting on Strep A transmission, who have identified a mode of transmission, and who reported attack rates. Risk of bias will be appraised using an appropriate tool. Our results will be described narratively and where feasible and appropriate, a meta-analysis utilizing the random-effects model will be used to aggregate the incidence proportions (attack rates) for each mode of transmission. In addition, we will also evaluate the emm genotype variants of the M protein causing Strep A infection and the association with transmission routes and attack rates, if any, by setting, socioeconomic background and geographical regions. Discussion We anticipate that this review will contribute to elucidating Strep A modes of transmission which in turn, will serve to inform evidence-based strategies including environmental health activities to reduce the transmission of Strep A in populations at risk of severe disease. Trial registration Systematic review registration: PROSPERO ( CRD42019138472 ).
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    Open Access
    Shared air: a renewed focus on ventilation for the prevention of tuberculosis transmission
    (Public Library of Science, 2014) Richardson, Eugene T; Morrow, Carl D; Kalil, Darryl B; Bekker, Linda-Gail; Wood, Robin
    BACKGROUND: Despite an improvement in the overall TB cure rate from 40-74% between 1995 and 2011, TB incidence in South Africa continues to increase. The epidemic is notably disquieting in schools because the vulnerable population is compelled to be present. Older learners (age 15-19) are at particular risk given a smear-positive rate of 427 per 100,000 per year and the significant amount of time they spend indoors. High schools are therefore important locations for potential TB infection and thus prevention efforts. Methods and FINDINGS: Using portable carbon dioxide monitors, we measured CO 2 in classrooms under non-steady state conditions. The threshold for tuberculosis transmission was estimated using a carbon dioxide-based risk equation. We determined a critical rebreathed fraction of carbon dioxide ( ) of 1·6%, which correlates with an indoor CO 2 concentration of 1000 ppm. These values correspond with a ventilation rate of 8·6 l/s per person or 12 air exchanges per hour (ACH) for standard classrooms of 180 m 3 . CONCLUSIONS: Given the high smear positive rate of high-school adolescents in South Africa, the proposal to achieve CO 2 levels of 1000ppm through natural ventilation (in the amount 12 ACH) will not only help achieve WHO guidelines for providing children with healthy indoor environments, it will also provide a low-cost intervention for helping control the TB epidemic in areas of high prevalence.