Vertical transmission of dengue viruses by mosquitoes of the Aedes scutellaris group.

Seventeen strains of mosquitoes belonging to 12 species in the Aedes scutellaris subgroup were tested for an ability to transmit one or more dengue virus serotype(s) vertically. Strains of virus employed for dengue types 1, 2, 3, and 4 were from Fiji, Bangkok, Burma, and Medan, respectively. After parental females were infected by intrathoracic inoculation, F1 larval and pupal progeny were tested for the presence of virus by inoculating aliquots of triturated suspensions into Toxorhynchites amboinensis mosquitoes. Dengue type 1 was transmitted vertically by 11 strains of mosquitoes representing 8 species with the highest filial infection rates observed for Ae. cooki (1.2%). Vertical transmission of the other dengue virus serotypes was observed for fewer species of mosquitoes, however the filial infection rates of those demonstrating vertical transmission were between 1%-2% for types 2 and 3, and about 0.5% for type 4. Tests with the progeny of individual Ae. cooki and Ae. polynesiensis infected with dengue virus types 1 and 3, respectively, showed that approximately greater than or equal to 50% of the parental females transmitted virus to their progeny. Highest filial infection rates were 6.7% for Ae. cooki and 4.6% for Ae. polynesiensis.