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Epidemiologic and Environmental Risk Factors of Rift Valley Fever in Southern Africa from 2008 to 2011
Background: Rift Valley fever (RVF) outbreaks have been associated with periods of widespread and above-normal rainfall over several months. Knowledge on the environmental factors influencing disease transmission dynamics has provided the basis for developing models to predict RVF outbreaks in Afric...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Mary Ann Liebert, Inc.
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4545538/ https://www.ncbi.nlm.nih.gov/pubmed/26273812 http://dx.doi.org/10.1089/vbz.2015.1774 |
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author | Glancey, Margaret M. Anyamba, Assaf Linthicum, Kenneth J. |
author_facet | Glancey, Margaret M. Anyamba, Assaf Linthicum, Kenneth J. |
author_sort | Glancey, Margaret M. |
collection | PubMed |
description | Background: Rift Valley fever (RVF) outbreaks have been associated with periods of widespread and above-normal rainfall over several months. Knowledge on the environmental factors influencing disease transmission dynamics has provided the basis for developing models to predict RVF outbreaks in Africa. From 2008 to 2011, South Africa experienced the worst wave of RVF outbreaks in almost 40 years. We investigated rainfall-associated environmental factors in southern Africa preceding these outbreaks. Methods: RVF epizootic records obtained from the World Animal Health Information Database (WAHID), documenting livestock species affected, location, and time, were analyzed. Environmental variables including rainfall and satellite-derived normalized difference vegetation index (NDVI) data were collected and assessed in outbreak regions to understand the underlying drivers of the outbreaks. Results: The predominant domestic vertebrate species affected in 2008 and 2009 were cattle, when outbreaks were concentrated in the eastern provinces of South Africa. In 2010 and 2011, outbreaks occurred in the interior and southern provinces affecting over 16,000 sheep. The highest number of cases occurred between January and April but epidemics occurred in different regions every year, moving from the northeast of South Africa toward the southwest with each progressing year. The outbreaks showed a pattern of increased rainfall preceding epizootics ranging from 9 to 152 days; however, NDVI and rainfall were less correlated with the start of the outbreaks than has been observed in eastern Africa. Conclusions: Analyses of the multiyear RVF outbreaks of 2008 to 2011 in South Africa indicated that rainfall, NDVI, and other environmental and geographical factors, such as land use, drainage, and topography, play a role in disease emergence. Current and future investigations into these factors will be able to contribute to improving spatial accuracy of models to map risk areas, allowing adequate time for preparation and prevention before an outbreak occurs. |
format | Online Article Text |
id | pubmed-4545538 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | Mary Ann Liebert, Inc. |
record_format | MEDLINE/PubMed |
spelling | pubmed-45455382015-09-23 Epidemiologic and Environmental Risk Factors of Rift Valley Fever in Southern Africa from 2008 to 2011 Glancey, Margaret M. Anyamba, Assaf Linthicum, Kenneth J. Vector Borne Zoonotic Dis Original Articles Background: Rift Valley fever (RVF) outbreaks have been associated with periods of widespread and above-normal rainfall over several months. Knowledge on the environmental factors influencing disease transmission dynamics has provided the basis for developing models to predict RVF outbreaks in Africa. From 2008 to 2011, South Africa experienced the worst wave of RVF outbreaks in almost 40 years. We investigated rainfall-associated environmental factors in southern Africa preceding these outbreaks. Methods: RVF epizootic records obtained from the World Animal Health Information Database (WAHID), documenting livestock species affected, location, and time, were analyzed. Environmental variables including rainfall and satellite-derived normalized difference vegetation index (NDVI) data were collected and assessed in outbreak regions to understand the underlying drivers of the outbreaks. Results: The predominant domestic vertebrate species affected in 2008 and 2009 were cattle, when outbreaks were concentrated in the eastern provinces of South Africa. In 2010 and 2011, outbreaks occurred in the interior and southern provinces affecting over 16,000 sheep. The highest number of cases occurred between January and April but epidemics occurred in different regions every year, moving from the northeast of South Africa toward the southwest with each progressing year. The outbreaks showed a pattern of increased rainfall preceding epizootics ranging from 9 to 152 days; however, NDVI and rainfall were less correlated with the start of the outbreaks than has been observed in eastern Africa. Conclusions: Analyses of the multiyear RVF outbreaks of 2008 to 2011 in South Africa indicated that rainfall, NDVI, and other environmental and geographical factors, such as land use, drainage, and topography, play a role in disease emergence. Current and future investigations into these factors will be able to contribute to improving spatial accuracy of models to map risk areas, allowing adequate time for preparation and prevention before an outbreak occurs. Mary Ann Liebert, Inc. 2015-08-01 /pmc/articles/PMC4545538/ /pubmed/26273812 http://dx.doi.org/10.1089/vbz.2015.1774 Text en © Margaret M. Glancey, et al., 2015; Published by Mary Ann Liebert, Inc. This Open Access article is distributed under the terms of the Creative Commons License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. |
spellingShingle | Original Articles Glancey, Margaret M. Anyamba, Assaf Linthicum, Kenneth J. Epidemiologic and Environmental Risk Factors of Rift Valley Fever in Southern Africa from 2008 to 2011 |
title | Epidemiologic and Environmental Risk Factors of Rift Valley Fever in Southern Africa from 2008 to 2011 |
title_full | Epidemiologic and Environmental Risk Factors of Rift Valley Fever in Southern Africa from 2008 to 2011 |
title_fullStr | Epidemiologic and Environmental Risk Factors of Rift Valley Fever in Southern Africa from 2008 to 2011 |
title_full_unstemmed | Epidemiologic and Environmental Risk Factors of Rift Valley Fever in Southern Africa from 2008 to 2011 |
title_short | Epidemiologic and Environmental Risk Factors of Rift Valley Fever in Southern Africa from 2008 to 2011 |
title_sort | epidemiologic and environmental risk factors of rift valley fever in southern africa from 2008 to 2011 |
topic | Original Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4545538/ https://www.ncbi.nlm.nih.gov/pubmed/26273812 http://dx.doi.org/10.1089/vbz.2015.1774 |
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