Introduction of Aedes albopictus in Gabon: what consequences for dengue and chikungunya transmission?

The 2007 outbreak of chikungunya in Gabon has indicated the potential of this disease to spread beyond its usual range ensuing from the expansion of the mosquito Aedes albopictus. A few cases of dengue (DEN) infection were also detected. Because little is known about the potential for Gabonese mosquito species to transmit both chikungunya and DEN viruses (DENV), we conducted studies to determine the susceptibility of Ae. albopictus and Aedes aegypti collected in Libreville to both viruses by experimental infections. Disseminated infection rates were high for Ae. albopictus infected with chikungunya virus (CHIKV) (66.7-86%) and low with DENV (13-21.4%). Moreover, Ae. aegypti sp. formosus was a less efficient vector of CHIKV than Ae. albopictus. The recent introduction and dissemination of chikungunya associated with the invasion of Ae. albopictus in Africa illustrates the potential for CHIKV to spread to other parts of the world.