Mosquito Species (Diptera: Culicidae) and the Transmission of Ross River Virus in Brisbane, Australia

Abstract

This study aimed to identify the major mosquito vectors of Ross River virus (family Togaviridae, genus Alphavirus, RRV) and to explore the threshold of mosquito abundance necessary for RRV transmission in Brisbane, Australia. Data on the monthly counts of RRV cases by statistical local areas from the Queensland Health and the monthly mosquito abundance in Brisbane between November 1998 and December 2001 from the Brisbane City Council were used to assess the pairwise relationship between mosquito abundance and the incidence of RRV disease over a range of time lags using cross-correlations. We used time series Poisson regression models to identify major mosquito species associated with incidence of RRV after adjusting for overdispersion, maximum temperature, autocorrelation, and seasonality. Our results show that Aedes vigilax (Skuse) (relative risk [RR] = 1.32; 95% CI = 1.01-1.74 per 100 mosquitoes per trap) and Culex annulirostris (Skuse) (RR = 1.14, 95% CI = 1.04-1.24 per 100 mosquitoes per trap) were most strongly associated with RRV transmission at a lag of 1 mo. Classification and regression tree (CART) analyses indicate that the occurrence of RRV was associated with an average monthly mosquito abundance ofAedes vigilax above 72 and Cx. annulirostris above 52. The validation analyses indicate that the crude agreement between predicted values and actual observations was 76% (sensitivity, 61%; specificity, 80%). The results may have applications as a decision support tool in planning disease control and risk-management programs.

Climate variability and Ross River virus infections in Riverland, South Australia, 1992–2004

“…The predictive model derived from historic data indicates that these models have an excellent goodness-of-fit. This is the first such report on RRV in an Australian temperate climate zone and the findings are consistent with previous Australian studies [11][12][13][14][15][16][17][18]. In addition, we have run different models with and without weather variables, showing that the model without the weather variables demonstrates a much worse goodness-of-fit.…”

“…Because of the different ecological characteristics of different species of mosquitoes, different vectors may be favoured as the weather changes. Maximum and minimum temperature, rainfall, relative humidity, SOI and high tides should all be considered [11,18]. We have examined the effect of climatic variables on notified RRV infections in Riverland, an inland area which includes the Murray River and has the highest notified incidence of RRV in South Australia [19,20].…”

“…For instance, there was an over-prediction in 1994 and 2001 as shown in Figure 2. Therefore additional studies, which incorporate more variables such as density of mosquitoes [12,18,31] and reservoirs such as marsupials could lead to new insights [6].…”

“…Many studies have examined the relationship between climate variability and RRV infections in different regions of Australia, most focusing on areas in northern Australia, such as the tropical regions of Queensland, the Northern Territory and Western Australia [7,[11][12][13][14][15][16][17][18]. Because domain vectors are probably different in various regions, climatic conditions in the regions are likely to play different roles in RRV transmission due to the sensitivity of different vectors to various climatic factors.…”

Bats as Potential Reservoir Hosts for Vector-Borne Diseases

“…camptorhynchus and Cx. annulirostris (Harley et al 2000;Hu et al 2006;Mackenzie et al 1994). There is also evidence that Ae.…”