Rift Valley fever in northern Senegal: A  modelling approach to analyse the processes underlying virus circulation recurrence

by Benoit Durand, Moustapha Lo Modou, Annelise Tran, Aminata Ba, Fafa Sow, Jaber Belkhiria, Assane Gueye Fall, Biram Biteye, Vladimir Grosbois, V éronique Chevalier 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 epidemiologic al 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 inAedes 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 ...
Source: PLoS Neglected Tropical Diseases - Category: Tropical Medicine Authors: Source Type: research