Combining hydrology and mosquito population models to identify the drivers of Rift Valley fever emergence in semi-arid regions of West Africa : consequences for control

Soti Valérie, Tran Annelise, Degenne Pascal, Chevalier Véronique, Lo Seen Danny, Thiongane Yaya, Diallo Mawlouth, Guégan Jean-François, Fontenille Didier. 2012. Combining hydrology and mosquito population models to identify the drivers of Rift Valley fever emergence in semi-arid regions of West Africa : consequences for control. PLoS Neglected Tropical Diseases, 6 (8):e1795, 11 p.

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Quartile : Q1, Sujet : TROPICAL MEDICINE / Quartile : Q1, Sujet : PARASITOLOGY

Abstract : Background Rift Valley fever (RVF) is a vector-borne viral zoonosis of increasing global importance. RVF virus (RVFV) is transmitted either through exposure to infected animals or through bites from different species of infected mosquitoes, mainly of Aedes and Culex genera. These mosquitoes are very sensitive to environmental conditions, which may determine their presence, biology, and abundance. In East Africa, RVF outbreaks are known to be closely associated with heavy rainfall events, unlike in the semi-arid regions of West Africa where the drivers of RVF emergence remain poorly understood. The assumed importance of temporary ponds and rainfall temporal distribution therefore needs to be investigated. Methodology/Principal Findings A hydrological model is combined with a mosquito population model to predict the abundance of the two main mosquito species (Aedes vexans and Culex poicilipes) involved in RVFV transmission in Senegal. The study area is an agropastoral zone located in the Ferlo Valley, characterized by a dense network of temporary water ponds which constitute mosquito breeding sites. The hydrological model uses daily rainfall as input to simulate variations of pond surface areas. The mosquito population model is mechanistic, considers both aquatic and adult stages and is driven by pond dynamics. Once validated using hydrological and entomological field data, the model was used to simulate the abundance dynamics of the two mosquito species over a 43-year period (1961-2003). We analysed the predicted dynamics of mosquito populations with regards to the years of main outbreaks. The results showed that the main RVF outbreaks occurred during years with simultaneous high abundances of both species. Conclusion/Significance Our study provides for the first time a mechanistic insight on RVFV transmission in West Africa. It highlights the complementary roles of Aedes vexans and Culex poicilipes mosquitoes in virus transmission, and recommends the identification of rainfall patterns favourable for RVFV amplification. (Résumé d'auteur)

Mots-clés Agrovoc : Aedes vexans, Culex, Hydrologie, Eau superficielle, Virus de la fièvre de la vallée du Rift, Modèle mathématique, Modèle de simulation, Dynamique des populations, Surveillance épidémiologique, Zone semi-aride, technique de prévision

Mots-clés géographiques Agrovoc : Sénégal, Afrique occidentale

Mots-clés complémentaires : Culex poicilipes

Mots-clés géographiques complémentaires : Ferlo

Classification Agris : L72 - Pests of animals
U10 - Computer science, mathematics and statistics
P10 - Water resources and management

Champ stratégique Cirad : Axe 4 (2005-2013) - Santé animale et maladies émergentes

Auteurs et affiliations

  • Tran Annelise, CIRAD-ES-UPR AGIRs (FRA) ORCID: 0000-0001-5463-332X
  • Degenne Pascal, CIRAD-ES-UMR TETIS (FRA)
  • Chevalier Véronique, CIRAD-ES-UPR AGIRs (FRA)
  • Lo Seen Danny, CIRAD-ES-UMR TETIS (FRA) ORCID: 0000-0002-7773-2109
  • Thiongane Yaya, ISRA (SEN)
  • Diallo Mawlouth, Institut Pasteur de Dakar (SEN)
  • Guégan Jean-François, CNRS (FRA)
  • Fontenille Didier, IRD (FRA)

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