Estimating the risk of Yellow fever in the Caribbean using vector competence data

Abstract Mosquito-borne diseases are spreading globally due to the expansion of the geographic range of competent mosquito vector species and increased human movement, especially infected travelers from endemic to non-endemic regions. Yellow fever (YF) has been largely controlled via mass delivery of an effective vaccine and mosquito control interventions. However, there are warning signs that YF is re-emerging in both Sub-Saharan Africa and South America. Imported from Africa to the Americas in slave ships, YF was responsible for devastating urban outbreaks for several centuries. In the Caribbean, the last YF outbreak was reported in 1908 in Martinique. The mosquito Aedes aegypti is the main vector for urban transmission in YF-endemic regions. However, it is unclear if all Ae. aegypti populations can effectively vector yellow fever virus (YFV), as there is growing evidence that intrinsic virus and mosquito host factors can significantly influence arbovirus transmission. We evaluated the vector competence of fifteen Ae. aegypti populations (nine from Martinique, two from Haiti, one from Guadeloupe, one from Cuba, one from Florida (USA), and one from Colombia) for five YFV genotypes (Bolivia, Ghana, Nigeria, Sudan, and Uganda) at 14 and 21 days post-infectious feeding. Mosquito populations from the Caribbean and the Americas were able to transmit the five YFV genotypes, in some cases achieving viral loads in mosquito saliva of up to several thousands of infectious virus particles, with YFV strains for Uganda and Bolivia having higher transmission success. We also observed that Ae. aegypti populations from Martinique were more susceptible to YFV infection than other populations from neighboring Caribbean islands, as well as North and South America. Our vector competence data suggest that the threat of re-emergence of YF in Martinique and the subsequent spread to Caribbean nations and beyond is plausible.