Predicting Rift Valley fever inter-epidemic activities and outbreak patterns: insights from a stochastic Host-Vector Model
Rift Valley fever (RVF) outbreaks are recurrent, occurring at irregular intervals of up to 15 years at least in East Africa. Between outbreaks disease inter-epidemic activities exist and occur at low levels and are maintained by female Aedes mcintoshi mosquitoes which transmit the virus to their eggs leading to disease persistence during unfavourable seasons. Here we formulate and analyse a full stochastic host-vector model with two routes of transmission: vertical and horizontal. By applying branching process theory we establish novel relationships between the basic reproduction number, R0, vertical transmission and the invasion and extinction probabilities. Optimum climatic conditions and presence of mosquitoes have not fully explained the irregular oscillatory behaviour of RVF outbreaks. Using our model without seasonality and applying van Kampen system-size expansion techniques, we provide an analytical expression for the spectrum of stochastic fluctuations, revealing how outbreaks multi-year periodicity varies with the vertical transmission. Our theory predicts complex fluctuations with a dominant period of 1 to 10 years which essentially depends on the efficiency of vertical transmission. Our predictions are then compared to temporal patterns of disease outbreaks in Tanzania, Kenya and South Africa. Our analyses show that interaction between nonlinearity, stochasticity and vertical transmission provides a simple but plausible explanation for the irregular oscillatory nature of RVF outbreaks. Therefore, we argue that while rainfall might be the major determinant for the onset and switch-off of an outbreak, the occurrence of a particular outbreak is also a result of a build up phenomena that is correlated to vertical transmission efficiency
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Public Library of Science
2016
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Subjects: | AGRICULTURAL SCIENCES AND BIOTECHNOLOGY, VIRUSES, RIFT VALLEY FEVER VIRUS, VECTOR-BORNE DISEASES, STOCHASTIC MODELS, |
Online Access: | http://hdl.handle.net/10883/18106 |
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dig-cimmyt-10883-181062023-11-08T19:10:56Z Predicting Rift Valley fever inter-epidemic activities and outbreak patterns: insights from a stochastic Host-Vector Model Pedro, S.A. Abelman, S. Tonnang, H. AGRICULTURAL SCIENCES AND BIOTECHNOLOGY VIRUSES RIFT VALLEY FEVER VIRUS VECTOR-BORNE DISEASES STOCHASTIC MODELS Rift Valley fever (RVF) outbreaks are recurrent, occurring at irregular intervals of up to 15 years at least in East Africa. Between outbreaks disease inter-epidemic activities exist and occur at low levels and are maintained by female Aedes mcintoshi mosquitoes which transmit the virus to their eggs leading to disease persistence during unfavourable seasons. Here we formulate and analyse a full stochastic host-vector model with two routes of transmission: vertical and horizontal. By applying branching process theory we establish novel relationships between the basic reproduction number, R0, vertical transmission and the invasion and extinction probabilities. Optimum climatic conditions and presence of mosquitoes have not fully explained the irregular oscillatory behaviour of RVF outbreaks. Using our model without seasonality and applying van Kampen system-size expansion techniques, we provide an analytical expression for the spectrum of stochastic fluctuations, revealing how outbreaks multi-year periodicity varies with the vertical transmission. Our theory predicts complex fluctuations with a dominant period of 1 to 10 years which essentially depends on the efficiency of vertical transmission. Our predictions are then compared to temporal patterns of disease outbreaks in Tanzania, Kenya and South Africa. Our analyses show that interaction between nonlinearity, stochasticity and vertical transmission provides a simple but plausible explanation for the irregular oscillatory nature of RVF outbreaks. Therefore, we argue that while rainfall might be the major determinant for the onset and switch-off of an outbreak, the occurrence of a particular outbreak is also a result of a build up phenomena that is correlated to vertical transmission efficiency 1-26 2017-02-28T18:19:59Z 2017-02-28T18:19:59Z 2016 Article http://hdl.handle.net/10883/18106 10.1371/journal.pntd.0005167 English https://figshare.com/articles/journal_contribution/Predicting_Rift_Valley_Fever_Inter-epidemic_Activities_and_Outbreak_Patterns_Insights_from_a_Stochastic_Host-Vector_Model/4488470 CIMMYT manages Intellectual Assets as International Public Goods. The user is free to download, print, store and share this work. In case you want to translate or create any other derivative work and share or distribute such translation/derivative work, please contact CIMMYT-Knowledge-Center@cgiar.org indicating the work you want to use and the kind of use you intend; CIMMYT will contact you with the suitable license for that purpose. Open Access PDF EAST AFRICA TANZANIA KENYA SOUTH AFRICA USA Public Library of Science 12 10 e0005167 PLoS Neglected Tropical Diseases |
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AGRICULTURAL SCIENCES AND BIOTECHNOLOGY VIRUSES RIFT VALLEY FEVER VIRUS VECTOR-BORNE DISEASES STOCHASTIC MODELS AGRICULTURAL SCIENCES AND BIOTECHNOLOGY VIRUSES RIFT VALLEY FEVER VIRUS VECTOR-BORNE DISEASES STOCHASTIC MODELS |
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AGRICULTURAL SCIENCES AND BIOTECHNOLOGY VIRUSES RIFT VALLEY FEVER VIRUS VECTOR-BORNE DISEASES STOCHASTIC MODELS AGRICULTURAL SCIENCES AND BIOTECHNOLOGY VIRUSES RIFT VALLEY FEVER VIRUS VECTOR-BORNE DISEASES STOCHASTIC MODELS Pedro, S.A. Abelman, S. Tonnang, H. Predicting Rift Valley fever inter-epidemic activities and outbreak patterns: insights from a stochastic Host-Vector Model |
description |
Rift Valley fever (RVF) outbreaks are recurrent, occurring at irregular intervals of up to 15 years at least in East Africa. Between outbreaks disease inter-epidemic activities exist and occur at low levels and are maintained by female Aedes mcintoshi mosquitoes which transmit the virus to their eggs leading to disease persistence during unfavourable seasons. Here we formulate and analyse a full stochastic host-vector model with two routes of transmission: vertical and horizontal. By applying branching process theory we establish novel relationships between the basic reproduction number, R0, vertical transmission and the invasion and extinction probabilities. Optimum climatic conditions and presence of mosquitoes have not fully explained the irregular oscillatory behaviour of RVF outbreaks. Using our model without seasonality and applying van Kampen system-size expansion techniques, we provide an analytical expression for the spectrum of stochastic fluctuations, revealing how outbreaks multi-year periodicity varies with the vertical transmission. Our theory predicts complex fluctuations with a dominant period of 1 to 10 years which essentially depends on the efficiency of vertical transmission. Our predictions are then compared to temporal patterns of disease outbreaks in Tanzania, Kenya and South Africa. Our analyses show that interaction between nonlinearity, stochasticity and vertical transmission provides a simple but plausible explanation for the irregular oscillatory nature of RVF outbreaks. Therefore, we argue that while rainfall might be the major determinant for the onset and switch-off of an outbreak, the occurrence of a particular outbreak is also a result of a build up phenomena that is correlated to vertical transmission efficiency |
format |
Article |
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AGRICULTURAL SCIENCES AND BIOTECHNOLOGY VIRUSES RIFT VALLEY FEVER VIRUS VECTOR-BORNE DISEASES STOCHASTIC MODELS |
author |
Pedro, S.A. Abelman, S. Tonnang, H. |
author_facet |
Pedro, S.A. Abelman, S. Tonnang, H. |
author_sort |
Pedro, S.A. |
title |
Predicting Rift Valley fever inter-epidemic activities and outbreak patterns: insights from a stochastic Host-Vector Model |
title_short |
Predicting Rift Valley fever inter-epidemic activities and outbreak patterns: insights from a stochastic Host-Vector Model |
title_full |
Predicting Rift Valley fever inter-epidemic activities and outbreak patterns: insights from a stochastic Host-Vector Model |
title_fullStr |
Predicting Rift Valley fever inter-epidemic activities and outbreak patterns: insights from a stochastic Host-Vector Model |
title_full_unstemmed |
Predicting Rift Valley fever inter-epidemic activities and outbreak patterns: insights from a stochastic Host-Vector Model |
title_sort |
predicting rift valley fever inter-epidemic activities and outbreak patterns: insights from a stochastic host-vector model |
publisher |
Public Library of Science |
publishDate |
2016 |
url |
http://hdl.handle.net/10883/18106 |
work_keys_str_mv |
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