High susceptibility to Chikungunya virus of Aedes aegypti from the French West Indies and French Guiana

Abstract

Objectives: To estimate the vector competence of Aedes aegypti populations sampled from distinct anthropogenic environments in French Guiana, Guadeloupe and Martinique for the strain CHIKV 06.21.

Methods: F(1)/F(2) females were orally infected at titres of 10(6) and 10(7.5) pfu/ml in blood-meals. Disseminated infection rates (DIR) of mosquitoes were estimated using indirect fluorescent antibody assay on heads' squashes, 7 or 14 days post-infection (pi).

Results: At a titre of 10(7.5) pfu/ml, DIR ranged from 88.9% to 100.0% and were not significantly different whether assessed at day 7 or 14 pi. At a titre of 10(6) pfu/ml, DIR observed 7 days pi ranged from 37.6 to 62.0%.

Conclusions: Ae. aegypti from French Guiana and French West Indies are highly competent to transmit CHIKV. An evaluation of DIR 7 days rather than 14 days pi is adequate to estimate vector competence. The titre of 10(6) pfu/ml allows us to distinguish Ae. aegypti populations originating from distinct environments (dense or diffuse housing) by their vector competence. This assessment is a prerequisite to better evaluate the potential risk of Chikungunya outbreaks once the virus is introduced from endemic regions.