1. Rift Valley fever in northern Senegal: A modelling approach to analyse the processes underlying virus circulation recurrence
- Author
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Durand, Benoit, Fall, Assane Gueye, Biteye, Biram, Chevalier, Véronique, Durand Id, Benoit, Lo Modou, Moustapha, Tran, Annelise, Ba, Aminata, Sow, Fafa, Belkhiria, Jaber, Gueye Fall, Assane, Biteye Id, Biram, Grosbois, Vladimir, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Institut Sénégalais de Recherches Agricoles [Dakar] (ISRA), Animal, Santé, Territoires, Risques et Ecosystèmes (UMR ASTRE), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Département Systèmes Biologiques (Cirad-BIOS), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad), Territoires, Environnement, Télédétection et Information Spatiale (UMR TETIS), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Département Environnements et Sociétés (Cirad-ES), School of Veterinary Medicine [UC Davis], University of California [Davis] (UC Davis), University of California-University of California, and This study was supported by Vmerge project (Emerging viral vector-borne diseases) and by the Ile-de-France Region as part of the DIM-1Health project. more...
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Male ,RNA viruses ,Rift Valley Fever ,[SDV]Life Sciences [q-bio] ,RC955-962 ,Population Dynamics ,Prevalence ,Marine and Aquatic Sciences ,Disease Vectors ,L73 - Maladies des animaux ,Mosquitoes ,Geographical Locations ,Aedes vexans ,Recurrence ,Seroepidemiologic Studies ,Aedes ,Arctic medicine. Tropical medicine ,Bunyaviruses ,MESH: Rift Valley Fever ,Dynamique des populations ,Rift Valley fever ,Socioeconomics ,Disease outbreaks ,Pathology and laboratory medicine ,Mammals ,education.field_of_study ,biology ,U10 - Informatique, mathématiques et statistiques ,Fièvre de la Vallée du Rift ,Eukaryota ,Ruminants ,MESH: Aedes ,Medical microbiology ,Senegal ,Insects ,Geography ,Infectious Diseases ,Serology ,Vertebrates ,Viruses ,[SDV.MP.VIR]Life Sciences [q-bio]/Microbiology and Parasitology/Virology ,Female ,Public aspects of medicine ,RA1-1270 ,Pathogens ,L72 - Organismes nuisibles des animaux ,Research Article ,Wet season ,Arthropoda ,Population ,Vector Borne Diseases ,Virus de la fièvre de la vallée du Rift ,Microbiology ,Bovines ,medicine ,Disease Transmission, Infectious ,Seroprevalence ,Humans ,Animals ,education ,Ponds ,Transmission des maladies ,Medicine and health sciences ,Models, Statistical ,Population Biology ,Organisms ,Viral pathogens ,Biology and Life Sciences ,Bodies of Water ,biology.organism_classification ,medicine.disease ,Rift Valley fever virus ,Invertebrates ,Microbial pathogens ,Insect Vectors ,Species Interactions ,Culicidae ,Modélisation ,Amniotes ,People and Places ,Africa ,Herd ,Earth Sciences ,Cattle ,[SDV.SPEE]Life Sciences [q-bio]/Santé publique et épidémiologie - Abstract
Rift Valley fever (RVF) is endemic in northern Senegal, a Sahelian area characterized by a temporary pond network that drive both RVF mosquito population dynamics and nomadic herd movements. To investigate the mechanisms that explain RVF recurrent circulation, we modelled a realistic epidemiological system at the pond level integrating vector population dynamics, resident and nomadic ruminant herd population dynamics, and nomadic herd movements recorded in Younoufere area. To calibrate the model, serological surveys were performed in 2015–2016 on both resident and nomadic domestic herds in the same area. Mosquito population dynamics were obtained from a published model trained in the same region. Model comparison techniques were used to compare five different scenarios of virus introduction by nomadic herds associated or not with vertical transmission in Aedes vexans. Our serological results confirmed a long lasting RVF endemicity in resident herds (IgG seroprevalence rate of 15.3%, n = 222), and provided the first estimation of RVF IgG seroprevalence in nomadic herds in West Africa (12.4%, n = 660). Multivariate analysis of serological data suggested an amplification of the transmission cycle during the rainy season with a peak of circulation at the end of that season. The best scenario of virus introduction combined yearly introductions of RVFV from 2008 to 2015 (the study period) by nomadic herds, with a proportion of viraemic individuals predicted to be larger in animals arriving during the 2nd half of the rainy season (3.4%). This result is coherent with the IgM prevalence rate (4%) found in nomadic herds sampled during the 2nd half of the rainy season. Although the existence of a vertical transmission mechanism in Aedes cannot be ruled out, our model demonstrates that nomadic movements are sufficient to account for this endemic circulation in northern Senegal., Author summary Rift Valley fever (RVF) is one of the most important vector borne disease in Africa, seriously affecting the health of domestic ruminants and humans and leading to severe economic consequences. This disease is endemic in northern Senegal, a Sahelian area characterized by a temporary pond network that drive both RVF mosquito population dynamics and nomadic herd movements. Two non-exclusive mechanisms may support this endemicity: recurrent introductions of the virus by nomadic animals, and vertical transmission of the virus (i.e. from infected female mosquito to eggs) in local Aedes populations. The authors followed resident and nomadic domestic herds for 1 year. They used the data thus obtained to model a realistic epidemiological system at the pond level integrating vector population dynamics, resident and nomadic ruminant herd population dynamics. They found that the best scenario explaining RVF remanence combined yearly introductions of RVFV by nomadic herds, with a viraemic proportion predicted to be larger in animals arriving during the 2nd half of the rainy season, which is consistent with an amplification of virus circulation in the area during the rainy season. Although the existence of a vertical transmission mechanism in Aedes cannot be ruled out, their results demonstrates that nomadic movements are sufficient to account for this endemic circulation in northern Senegal. more...
- Published
- 2020
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