Enhanced vector competence of Aedes aegypti (Diptera: Culicidae) from the Torres Strait compared with mainland Australia for dengue 2 and 4 viruses.
Australian Aedes aegypti (L.) mosquitoes colonized from the Torres Strait and three mainland localities (Charters Towers, Townsville, and Cairns) were fed on blood suspensions containing dengue virus type 2 (DEN-2) or dengue virus type 4 (DEN-4). Variation was found in oral susceptibility to DEN-2 (59 -99% infection) and DEN-4 (28-79% infection) among Ae. aegypti assayed for virus at 8, 12, 16, or 20 d after ingestion of infected blood. Torres Strait Ae. aegypti were the most susceptible to DEN-2 and were significantly more efficient in transmission to capillary tube at 16 d (76% transmission) than mainland Ae. aegypti populations (20-28% transmission). Torres Strait Ae. aegypti were also the most susceptible to DEN-4, although transmission did not vary significantly from mainland populations at 16 d (12% compared with 0-4%) or 20 d (16% compared with 4-16%). Disseminated infection (i.e., leg infection) with either DEN-2 or DEN-4 was not an accurate predictor of transmission potential. This study demonstrates differences among Australian Ae. aegypti populations in vector competence for DEN-2 and DEN-4. Torres Strait Ae. aegypti were more frequently infected and able to transmit DEN-2 at higher rates than mainland populations. These data indicate that the Torres Strait region is potentially more receptive to dengue transmission than mainland localities, a finding discussed with respect to past outbreaks.
Knox
T B
TB
Queensland Institute of Medical Research, University of Queensland Australian Centre for International and Tropical Health and Nutrition, Post Office Royal Brisbane Hospital, Herston Qld 4029, Australia.
Kay
B H
BH
Hall
R A
RA
Ryan
P A
PA
D000330:Aedes / Q000821:virology*; D000818:Animals; D003715:Dengue / Q000517:prevention & control* / Q000635:transmission*; D003716:Dengue Virus / Q000254:growth & development / Q000302:isolation & purification*; D005843:Geography; D006801:Humans; D007303:Insect Vectors / Q000821:virology*; D010139:Pacific Islands; D011793:Queensland