Detection of a novel insect specific flavivirus across ecologically diverse populations of Aedes aegypti on the Caribbean Island of Saint Lucia

Abstract

Outbreaks of mosquito-borne arboviral diseases including dengue virus (DENV), Zika virus (ZIKV), yellow fever virus (YFV) and chikungunya virus (CHIKV) have recently occurred in the Caribbean. The geographical range of the principle vectors responsible for transmission, Aedes (Ae.) aegypti and Ae. albopictus is increasing and greater mosquito surveillance is needed in the Caribbean given international tourism is so prominent. The island of Saint Lucia has seen outbreaks of DENV and CHIKV in the past five years but vector surveillance has been limited with the last studies dating back to the late 1970s. Natural disasters have changed the landscape of Saint Lucia and the island has gone through significant urbanisation. In this study, we conducted an entomological survey of Ae. aegypti and Ae. albopictus distribution across the island and analysed environmental parameters associated with the presence of these species. Although we collected Ae. aegypti across a range of sites across the island, no Ae. albopictus were collected despite traps being placed in diverse ecological settings. The number of Ae. aegypti collected was significantly associated with higher elevation and semi-urban settings yielded female mosquito counts per trap-day that were 5-fold lower than urban settings. Screening for arboviruses revealed a high prevalence of a novel insect-specific flavivirus closely related to cell fusing agent virus (CFAV). We discuss the implications that natural disasters, water storage and lack of mosquito surveillance have on arboviral outbreaks in Saint Lucia and implications for insect only flaviviruses on surveillance and detection of pathogenic flaviviruses.