Abstract
BackgroundMany zoonotic infectious diseases have emerged and re-emerged over the last two decades. There has been a significant increase in vector-borne diseases due to climate variations that lead to environmental changes favoring the development and adaptation of vectors. This study was carried out to improve knowledge of the ecology of mosquito vectors involved in the transmission of Rift Valley fever virus (RVFV) in Senegal.MethodsAn entomological survey was conducted in three Senegalese agro-systems, Senegal River Delta (SRD), Senegal River Valley (SRV) and Ferlo, during the rainy season (July to November) of 2014 and 2015. Mosquitoes were trapped using CDC light traps set at ten sites for two consecutive nights during each month of the rainy season, for a total of 200 night-traps. Ecological indices were calculated to characterize the different populations of RVFV mosquito vectors. Generalized linear models with mixed effects were used to assess the influence of climatic conditions on the abundance of RVFV mosquito vectors.ResultsA total of 355,408 mosquitoes belonging to 7 genera and 35 species were captured in 200 night-traps. RVFV vectors represented 89.02% of the total, broken down as follows: Ae. vexans arabiensis (31.29%), Cx. poicilipes (0.6%), Cx. tritaeniorhynchus (33.09%) and Ma. uniformis (24.04%). Comparison of meteorological indices (rainfall, temperature, relative humidity), abundances and species diversity indicated that there were no significant differences between SRD and SRV (P = 0.36) while Ferlo showed significant differences with both (P < 0.001). Mosquito collection increased significantly with temperature for Ae. vexans arabiensis (P < 0.001), Cx. tritaeniorhynchus (P = 0.04) and Ma. uniformis (P = 0.01), while Cx. poicilipes decreased (P = 0.003). Relative humidity was positively and significantly associated with the abundances of Ae. vexans arabiensis (P < 0.001), Cx. poicilipes (P = 0.01) and Cx. tritaeniorhynchus (P = 0.007). Rainfall had a positive and significant effect on the abundances of Ae. vexans arabiensis (P = 0.005). The type of biotope (temporary ponds, river or lake) around the trap points had a significant effect on the mosquito abundances (P < 0.001).ConclusionsIn terms of species diversity, the SRD and SRV ecosystems are similar to each other and different from that of Ferlo. Meteorological indices and the type of biotope (river, lake or temporary pond) have significant effects on the abundance of RVFV mosquito vectors.
Highlights
Many zoonotic infectious diseases have emerged and re-emerged over the last two decades
Of the year and the ecosystem, the values of equitability (E) approached zero, reflecting an unbalanced population dominated by only one species: Cx. tritaeniorhynchus in Senegal River Delta (SRD) and Senegal River Valley (SRV) and Ae. vexans arabiensis in the Ferlo area
Comparing the ecological indices of composition and structure (Table 2) for Diama (SRD) and Dandé Mayo Loboudou (DML) (SRV), we found that there was no significant difference (W = 895.5, P = 0.36) in abundances and species diversity for the two sites
Summary
Many zoonotic infectious diseases have emerged and re-emerged over the last two decades. This study was carried out to improve knowledge of the ecology of mosquito vectors involved in the transmission of Rift Valley fever virus (RVFV) in Senegal. Many human and animal infectious diseases with major impacts on public and veterinary health have emerged or re-emerged over the last two decades [1,2,3]. Rift Valley fever virus (RVFV) is an emerging arbovirus considered to be a major public and veterinary health problem. The recent RVF emergence and re-emergence are related to genetic, biological, environmental, climatic, political, economic, demographic and social factors [12,13,14,15,16]
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