Ecological distribution and population dynamics of Rift Valley fever virus mosquito vectors (Diptera, Culicidae) in Senegal

Bitèye, Biram; Fall, Assane Guèye; Ciss, Mamadou; Seck, Momar Talla; Apolloni, Andrea; Fall, Moussa; Tran, Annelise; Gimonneau, Geoffrey

doi:10.1186/s13071-017-2591-9

Cited by 48 publications

(47 citation statements)

References 42 publications

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“…This high rate of mixed meals could be explained by the fact that August is the period corresponding to the peak abundance of Ae. vexans arabiensis [53] but also to the scarcity of hosts. In fact, this leads to the higher densities of vectors that are at the origin of a greater nuisance and consequently of a self-defense reflex in hosts.…”

Section: Discussionmentioning

confidence: 99%

Feeding behavior of Aedes (Aedimorphus) vexans arabiensis, a Rift valley fever virus vector in the Ferlo pastoral ecosystem of Senegal

Bitèye

Fall

Seck

et al. 2019

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25Host-vector contact is a key factor in vectorial capacity assessment and thus the 26 transmission of mosquito-borne viruses such as Rift Valley Fever (RVF), an emerging zoonotic 27 disease of interest in West Africa. The knowledge of the host-feeding patterns of vector species 28 constitutes a key element in the assessment of their epidemiological importance in a given 29 environment. The aim of this work was to identify the blood meal origins of Aedes vexans 30 arabiensis Patton (Diptera: Culicidae), the main vector of RVF virus in the Ferlo pastoral 31 ecosystem of Senegal. Engorged female mosquitoes were collected in Younouféré in the 32 pastoral ecosystem in the Ferlo region during the 2014 rainy season. CDC light CO2-baited 33 traps were set at six sites for two consecutive nights every month from July to November. 34 Domestic animals present around traps were identified and counted for each trapping session. 35 Blood meal sources of engorged mosquitoes were identified using a vertebrate-specific 36 multiplexed primer set based on cytochrome b. Blood meal sources were successfully identified 37 for 319 out of 416 blood-fed females (76.68%), of which 163 (51.1%) were single meals, 146 38 (45.77%) mixed meals from two different hosts and 10 (3.13%) mixed meals from three 39 different hosts. Aedes vexans arabiensis fed preferentially on mammals especially on horse 40 compared to other hosts (P < 0.001). Proportions of single and mixed meals showed significant 41 temporal (P < 0.001) and spatial variations (P < 0.001) according to hosts availability. Aedes 42 vexans arabiensis shows an opportunistic feeding behavior depending on the host availability. 43 Results were discussed in relation with the Rift valley fever virus transmission and vector 44 involvement as well as its primary hosts. 45 Keywords: Rift valley fever, blood meal origins, Aedes vexans arabiensis, vertebrate-specific 46 multiplexed primers, Senegal. 47 Introduction 3 48 Rift Valley Fever (RVF) is an emerging zoonotic vector-borne viral infection [1] considered 49 as a major problem of public and veterinary health as evidenced by various outbreaks in Africa 50 [2-6]. This disease causes significant economic gaps in terms of animal deaths and economic 51 losses in the affected countries [7-9]. Mosquitoes of the genera Aedes and Culex are the main 52 vectors of RVF virus (RVFV) and transmission mainly occur during inter-epizootic periods [1]. 53 RVF is endemic in Senegal, especially in the Ferlo region [10, 11]. The transmission of the 54 virus is seasonal and insured by Ae. vexans arabiensis and Cx. poicilipes with peaks of 55 transmission at the end of the rainy season [12-14]. Disease control is difficult because 56 mosquito vectors are able to fly on long distances and escape the border sanitary barriers. 57 Moreover, vector control methods are not used to control RVF outbreaks because they are 58 costly and difficult to implement and could have important environmental and ecological 59 consequences. However, host such as cattle could be trea...

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Section: Discussionmentioning

confidence: 99%

Feeding behavior of Aedes (Aedimorphus) vexans arabiensis, a Rift valley fever virus vector in the Ferlo pastoral ecosystem of Senegal

Bitèye

Fall

Seck

et al. 2019

Preprint

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“…Their filling dynamics is estimated with an existing 7 hydrologic model (Soti et al, 2010). The predictions of this model have been validated against entomological data collected in several sites in our study area (Biteye et al, 2018). We used weekly mosquito abundance for three consecutive rainy seasons (July to November 2014, 2015 and 2016).…”

Section: Spatio-temporal Data On Vector Abundancementioning

confidence: 99%

It’s risky to wander in September: modelling the epidemic potential of Rift Valley fever in a Sahelian setting

Cecilia

Métras

Fall

et al. 2020

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Estimating the epidemic potential of vector-borne diseases, along with the relative contribution of underlying mechanisms, is crucial for animal and human health worldwide. In West African Sahel, several outbreaks of Rift Valley fever (RVF) have occurred over the last decades, but uncertainty remains about the conditions necessary to trigger these outbreaks. We use the basic reproduction number (R0) as a measure of RVF epidemic potential in northern Senegal, and map its value in two distinct ecosystems, namely the Ferlo and the Senegal river delta and valley. We consider three consecutive rainy seasons (July-November 2014, 2015 and 2016) and account for several vector and animal species. Namely, we parametrize our model with estimates of Aedes vexans arabiensis, Culex poicilipes, Culex tritaeniorhynchus, cattle, sheep and goats abundances. The impact of RVF virus introduction is assessed every week, in 4367 pixels of 3,5km2. The results of our analysis indicate that September was the month with highest epidemic potential in each study area, while at-risk locations varied between seasons. We show that decreased vector densities do not highly reduce R0 and that cattle immunity has a greater impact on reducing transmission than small ruminants immunity. The host preferences of vectors and the temperature-dependent time interval between their blood meals are crucial parameters needing further biological investigations.

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“…vexans in northern Senegal, and although a recent entomological survey showed very low densities of Ae. mcintoshi in this area [37, 38], the existence of this mechanism cannot be ruled out. Another mechanism could imply the survival of RVFV in hibernating Culex mosquitoes as demonstrated with West Nile virus in the United States [39–41].…”

Section: Introductionmentioning

confidence: 99%

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

Durand

Modou

Tran

et al. 2019

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23 24 2 25 Abstract: 26 Rift Valley fever (RVF) is endemic in northern Senegal, a Sahelian area characterized by a temporary 27 pond network that drive both RVF mosquito population dynamics and nomadic herd movements. To 28 investigate the mechanisms that explain RVF recurrent circulation, we modelled a realistic 29 epidemiological system at the pond level integrating vector population dynamics, resident and nomadic 30 ruminant herd population dynamics, and nomadic herd movements recorded in Younoufere area [1]. To 31 calibrate the model, serological surveys were performed in 2015-2016 on both resident and nomadic 32 herds in the same area. Mosquito population dynamics were obtained from a published model trained in 33 the same region [2]. Model comparison techniques were used to compare five different scenarios of 34 virus introduction by nomadic herds associated or not with vertical transmission in Aedes vexans. Our 35 serological results confirmed a long lasting RVF endemicity in resident herds (IgG seroprevalence rate 36 of 15.3%, n=222), and provided the first estimation of RVF IgG seroprevalence in nomadic herds in 37 West Africa (12.4%, n=660). Multivariate analysis of serological data suggested an amplification of the 38 transmission cycle during the rainy season with a peak of circulation at the end of that season. The best 39 scenario of virus introduction combined yearly introductions of RVFV from 2008 to 2015 (the study 40 period) by nomadic herds, with a proportion of viraemic individuals predicted to be larger in animals 41 arriving during the 2 nd half of the rainy season (3.4%). This result is coherent with the IgM prevalence 42 rate (4%) found in nomadic herds sampled during the 2 nd half of the rainy season. Although the existence 43 of a vertical transmission mechanism in Aedes cannot be ruled out, our model demonstrates that nomadic 44 movements are sufficient to account for this endemic circulation in northern Senegal. 45 46 3 47 Author summary: 48 Rift Valley fever (RVF) is one of the most important vector borne disease in Africa, seriously affecting 49 the health of domestic ruminants and humans and leading to severe economic consequences. This 50 disease is endemic in northern Senegal, a Sahelian area characterized by a temporary pond network that 51 drive both RVF mosquito population dynamics and nomadic herd movements. Two non-exclusive 52 mechanisms may support this endemicity: recurrent introductions of the virus by nomadic animals, and 53 vertical transmission of the virus (i.e. from infected female mosquito to eggs) in local Aedes populations. 54 The authors followed up during 1 year resident and nomadic herds. They used the data thus obtained to 55 model a realistic epidemiological system at the pond level integrating vector population dynamics, 56 resident and nomadic ruminant herd population dynamics. They found that the best scenario explaining 57 RVF remanence combined yearly introductions of RVFV by nomadic herds, with a proportion of 58 viraemic predicted to be larger in anima...

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Ecological distribution and population dynamics of Rift Valley fever virus mosquito vectors (Diptera, Culicidae) in Senegal

Cited by 48 publications

References 42 publications

Feeding behavior of Aedes (Aedimorphus) vexans arabiensis, a Rift valley fever virus vector in the Ferlo pastoral ecosystem of Senegal

Feeding behavior of Aedes (Aedimorphus) vexans arabiensis, a Rift valley fever virus vector in the Ferlo pastoral ecosystem of Senegal

It’s risky to wander in September: modelling the epidemic potential of Rift Valley fever in a Sahelian setting

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

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