Vertical transmission of dengue viruses by Aedes mediovittatus.

Aedes mediovittatus, a forest and peridomestic mosquito found in the Caribbean area, has previously been shown to be highly susceptible to oral infection with dengue viruses in the laboratory. In the present study, the species was found to transmit all four dengue serotypes vertically (i.e., from one generation to another) at rates much higher than any observed previously for flaviviruses in mosquitoes. Vertical transmission rates (the percentage of parent females transmitting to one or more progeny) ranged up to 95%. Filial infection rates (the percentage of infected progeny) varied widely by family but rates greater than or equal to 20% for individual families were not uncommon. Since Ae. mediovittatus feeds readily on humans and is relatively abundant, there is no apparent reason why it would not serve as a vector of dengue. If it does, vertical transmission of the virus in this species would contribute to the maintenance of viral endemicity.