Vector competence of Aedes vexans (Meigen), Culex poicilipes (Theobald) and Cx. quinquefasciatus Say from Senegal for West and East African lineages of Rift Valley fever virus

Abstract

BackgroundRift Valley fever virus (RVFV; Phlebovirus, Bunyaviridae) is a mosquito–borne, zoonotic pathogen. In Senegal, RVFV was first isolated in 1974 from Aedes dalzieli (Theobald) and thereafter from Ae. fowleri (de Charmoy), Ae. ochraceus Theobald, Ae. vexans (Meigen), Culex poicilipes (Theobald), Mansonia africana (Theobald) and Ma. uniformis (Theobald). However, the vector competence of these local species has never been demonstrated making hypothetical the transmission cycle proposed for West Africa based on serological data and mosquito isolates.MethodsAedes vexans and Cx. poicilipes, two common mosquito species most frequently associated with RVFV in Senegal, and Cx. quinquefasciatus, the most common domestic species, were assessed after oral feeding with three RVFV strains of the West and East/central African lineages. Fully engorged mosquitoes (420 Ae. vexans, 563 Cx. quinquefasciatus and 380 Cx. poicilipes) were maintained at 27 ± 1 °C and 70–80 % relative humidity. The saliva, legs/wings and bodies were tested individually for the RVFV genome using real-time RT-PCR at 5, 10, 15 and 20 days post exposure (dpe) to estimate the infection, dissemination, and transmission rates. Genotypic characterisation of the 3 strains used were performed to identify factors underlying the different patterns of transmission.ResultsThe infection rates varied between 30.0–85.0 % for Ae. vexans, 3.3–27 % for Cx. quinquefasciatus and 8.3–46.7 % for Cx. poicilipes, and the dissemination rates varied between 10.5–37 % for Ae. vexans, 9.5–28.6 % for Cx. quinquefasciatus and 3.0–40.9 % for Cx. poicilipes. However only the East African lineage was transmitted, with transmission rates varying between 13.3–33.3 % in Ae. vexans, 50 % in Cx. quinquefasciatus and 11.1 % in Cx. poicilipes. Culex mosquitoes were less susceptible to infection than Ae. vexans. Compared to other strains, amino acid variation in the NSs M segment proteins of the East African RVFV lineage human-derived strain SH172805, might explain the differences in transmission potential.ConclusionOur findings revealed that all the species tested were competent for RVFV with a significant more important role of Ae. vexans compared to Culex species and a highest potential of the East African lineage to be transmitted.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1383-y) contains supplementary material, which is available to authorized users.

RVFV Infection in Goats by Different Routes of Inoculation

“…Studies have shown that RVFV epidemics typically follow periods of heavy rainfall conducive to large mosquito populations (Davies, Linthicum, & James, 1985;Hassan, Ahlm, Sang, & Evander, 2011;Leedale, Jones, Caminade, & Morse, 2016;Redding, Tiedt, Lo Iacono, Bett, & Jones, 2017) as well as the trade and importation of infected animals into susceptible regions (Napp et al, 2018). In Africa, RVFV is mainly transmitted by the Aedes aegypti mosquito, however, a growing number of studies have made it clear that other mosquito species present in Asia, Europe and North/South America are experimentally competent as RVFV vectors (Brustolin et al, 2017;Ndiaye et al, 2016;Turell et al, 2015). Therefore, if RVFV were to be introduced into other continents and their endemic mosquito populations, it could cause widespread epidemics and could seriously impact the health of human populations and economically important livestock herds.…”

Vector competence of anthropophilic mosquitoes for a new mesonivirus in Senegal

“…The Cx. quinquefasciatus population used in this study has been proven competent for Rift Valley Fever virus (RVFV) [22]. Both Culex species are vectors of many other arboviruses, including West Nile, Japanese encephalitis viruses [23,24] and RVFV.…”

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

“…v. arabiensis and C. poicilipes are confirmed vectors of RVFV in Senegal (Fontenille et al, 1998;Diallo et al, 2000;Ndiaye et al, 2016). C. tritaeniorhynchus is highly abundant and was identified as a RVFV vector in the 2000 outbreak in Saudi Arabia (Jupp et al, 2002).…”