EXPERIMENTAL TRANSMISSION OF EASTERN EQUINE ENCEPHALITIS-VIRUS BY STRAINS OF AEDES-ALBOPICTUS AND A-TAENIORHYNCHUS (DIPTERA, CULICIDAE)

The vector competence of Aedes taeniorhynchus (Wiedemann) and four strains of Aedes albopictus (Skuse) was assessed for eastern equine encephalitis (EEE) virus isolated from Ae. albopictus collected in Polk County, Florida. Both species became infected with and transmitted EEE virus by bite after feeding on 1-d-old chicks that had been inoculated with EEE virus (viremia = 10(10.1) plaque-forming units [PFU] per ml of blood). However, when fed on an older chick with a lower viremia (viremia = 10(6.1) PFU per ml of blood), Ae. albopictus was significantly more susceptible to infection (90%, n = 61) than was Ae. taeniorhynchus (15%, n = 40). Transmission was also significantly more efficient by Ae. albopictus (36%, n = 44), than by Ae. taeniorhynchus (0%, n = 14). These data, combined with the recent isolation of EEE virus from Ae. albopictus and its opportunistic feeding behavior, indicate that Ae. albopictus could function as a bridge vector between the enzootic Culiseta melanura (Coq.)-avian cycle and susceptible mammalian hosts.