Elevation and cholera: an epidemiological spatial analysis of the cholera epidemic in Harare, Zimbabwe, 2008-2009

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dc.contributor.authorLuque-Fernandez, Miguel Angelen_ZA
dc.contributor.authorSchomaker, Michaelen_ZA
dc.contributor.authorMason, Peteren_ZA
dc.contributor.authorFesselet, Jeanen_ZA
dc.contributor.authorBaudot, Yvesen_ZA
dc.contributor.authorBoulle, Andrewen_ZA
dc.contributor.authorMaes, Peteren_ZA
dc.date.accessioned2015-11-18T03:58:47Z
dc.date.available2015-11-18T03:58:47Z
dc.date.issued2012en_ZA
dc.description.abstractBACKGROUND: In highly populated African urban areas where access to clean water is a challenge, water source contamination is one of the most cited risk factors in a cholera epidemic. During the rainy season, where there is either no sewage disposal or working sewer system, runoff of rains follows the slopes and gets into the lower parts of towns where shallow wells could easily become contaminated by excretes. In cholera endemic areas, spatial information about topographical elevation could help to guide preventive interventions. This study aims to analyze the association between topographic elevation and the distribution of cholera cases in Harare during the cholera epidemic in 2008 and 2009. METHODS: We developed an ecological study using secondary data. First, we described attack rates by suburb and then calculated rate ratios using whole Harare as reference. We illustrated the average elevation and cholera cases by suburbs using geographical information. Finally, we estimated a generalized linear mixed model (under the assumption of a Poisson distribution) with an Empirical Bayesian approach to model the relation between the risk of cholera and the elevation in meters in Harare. We used a random intercept to allow for spatial correlation of neighboring suburbs. RESULTS: This study identifies a spatial pattern of the distribution of cholera cases in the Harare epidemic, characterized by a lower cholera risk in the highest elevation suburbs of Harare. The generalized linear mixed model showed that for each 100 meters of increase in the topographical elevation, the cholera risk was 30% lower with a rate ratio of 0.70 (95% confidence interval=0.66-0.76). Sensitivity analysis confirmed the risk reduction with an overall estimate of the rate ratio between 20% and 40%. CONCLUSION: This study highlights the importance of considering topographical elevation as a geographical and environmental risk factor in order to plan cholera preventive activities linked with water and sanitation in endemic areas. Furthermore, elevation information, among other risk factors, could help to spatially orientate cholera control interventions during an epidemic.en_ZA
dc.identifier.apacitationLuque-Fernandez, M. A., Schomaker, M., Mason, P., Fesselet, J., Baudot, Y., Boulle, A., & Maes, P. (2012). Elevation and cholera: an epidemiological spatial analysis of the cholera epidemic in Harare, Zimbabwe, 2008-2009. <i>BMC Public Health</i>, http://hdl.handle.net/11427/15082en_ZA
dc.identifier.chicagocitationLuque-Fernandez, Miguel Angel, Michael Schomaker, Peter Mason, Jean Fesselet, Yves Baudot, Andrew Boulle, and Peter Maes "Elevation and cholera: an epidemiological spatial analysis of the cholera epidemic in Harare, Zimbabwe, 2008-2009." <i>BMC Public Health</i> (2012) http://hdl.handle.net/11427/15082en_ZA
dc.identifier.citationFernandez, M. A. L., Schomaker, M., Mason, P. R., Fesselet, J. F., Baudot, Y., Boulle, A., & Maes, P. (2012). Elevation and cholera: an epidemiological spatial analysis of the cholera epidemic in Harare, Zimbabwe, 2008-2009. BMC public health, 12(1), 442.en_ZA
dc.identifier.ris TY - Journal Article AU - Luque-Fernandez, Miguel Angel AU - Schomaker, Michael AU - Mason, Peter AU - Fesselet, Jean AU - Baudot, Yves AU - Boulle, Andrew AU - Maes, Peter AB - BACKGROUND: In highly populated African urban areas where access to clean water is a challenge, water source contamination is one of the most cited risk factors in a cholera epidemic. During the rainy season, where there is either no sewage disposal or working sewer system, runoff of rains follows the slopes and gets into the lower parts of towns where shallow wells could easily become contaminated by excretes. In cholera endemic areas, spatial information about topographical elevation could help to guide preventive interventions. This study aims to analyze the association between topographic elevation and the distribution of cholera cases in Harare during the cholera epidemic in 2008 and 2009. METHODS: We developed an ecological study using secondary data. First, we described attack rates by suburb and then calculated rate ratios using whole Harare as reference. We illustrated the average elevation and cholera cases by suburbs using geographical information. Finally, we estimated a generalized linear mixed model (under the assumption of a Poisson distribution) with an Empirical Bayesian approach to model the relation between the risk of cholera and the elevation in meters in Harare. We used a random intercept to allow for spatial correlation of neighboring suburbs. RESULTS: This study identifies a spatial pattern of the distribution of cholera cases in the Harare epidemic, characterized by a lower cholera risk in the highest elevation suburbs of Harare. The generalized linear mixed model showed that for each 100 meters of increase in the topographical elevation, the cholera risk was 30% lower with a rate ratio of 0.70 (95% confidence interval=0.66-0.76). Sensitivity analysis confirmed the risk reduction with an overall estimate of the rate ratio between 20% and 40%. CONCLUSION: This study highlights the importance of considering topographical elevation as a geographical and environmental risk factor in order to plan cholera preventive activities linked with water and sanitation in endemic areas. Furthermore, elevation information, among other risk factors, could help to spatially orientate cholera control interventions during an epidemic. DA - 2012 DB - OpenUCT DO - 10.1186/1471-2458-12-442 DP - University of Cape Town J1 - BMC Public Health LK - https://open.uct.ac.za PB - University of Cape Town PY - 2012 T1 - Elevation and cholera: an epidemiological spatial analysis of the cholera epidemic in Harare, Zimbabwe, 2008-2009 TI - Elevation and cholera: an epidemiological spatial analysis of the cholera epidemic in Harare, Zimbabwe, 2008-2009 UR - http://hdl.handle.net/11427/15082 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/15082
dc.identifier.urihttp://dx.doi.org/10.1186/1471-2458-12-442
dc.identifier.vancouvercitationLuque-Fernandez MA, Schomaker M, Mason P, Fesselet J, Baudot Y, Boulle A, et al. Elevation and cholera: an epidemiological spatial analysis of the cholera epidemic in Harare, Zimbabwe, 2008-2009. BMC Public Health. 2012; http://hdl.handle.net/11427/15082.en_ZA
dc.language.isoengen_ZA
dc.publisherBioMed Central Ltden_ZA
dc.publisher.departmentInstitute of Infectious Disease and Molecular Medicineen_ZA
dc.publisher.facultyFaculty of Health Sciencesen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.rightsThis is an Open Access article distributed under the terms of the Creative Commons Attribution Licenseen_ZA
dc.rights.holder2012 Luque Fernandez et al.; licensee BioMed Central Ltd.en_ZA
dc.rights.urihttp://creativecommons.org/licenses/by/2.0en_ZA
dc.sourceBMC Public Healthen_ZA
dc.source.urihttp://www.biomedcentral.com/bmcpublichealth/en_ZA
dc.subject.otherhighly populated African urban areasen_ZA
dc.subject.othercholera epidemicen_ZA
dc.subject.othercholera risk factorsen_ZA
dc.subject.otherwater source contaminationen_ZA
dc.titleElevation and cholera: an epidemiological spatial analysis of the cholera epidemic in Harare, Zimbabwe, 2008-2009en_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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