Ross River Virus Disease Clusters and Spatial Relationship with Mosquito Biting Exposure in Redland Shire, Southern Queensland, Australia

Abstract

The spatial heterogeneity in the risk of Ross River virus (family Togaviridae, genus Alphavirus, RRV) disease, the most common mosquito-borne disease in Australia, was examined in Redland Shire in southern Queensland, Australia. Disease cases, complaints from residents of intense mosquito biting exposure, and human population data were mapped using a geographic information system. Surface maps of RRV disease age-sex standardized morbidity ratios and mosquito biting complaint morbidity ratios were created. To determine whether there was significant spatial variation in disease and complaint patterns, a spatial scan analysis method was used to test whether the number of cases and complaints was distributed according to underlying population at risk. Several noncontiguous areas in proximity to productive saline water habitats of Aedes vigilax (Skuse), a recognized vector of RRV, had higher than expected numbers of RRV disease cases and complaints. Disease rates in human populations in areas which had high numbers of adult Ae. vigilax in carbon dioxide- and octenol-baited light traps were up to 2.9 times those in areas that rarely had high numbers of mosquitoes. It was estimated that targeted control of adult Ae. vigilax in these high-risk areas could potentially reduce the RRV disease incidence by an average of 13.6%. Spatial correlation was found between RRV disease risk and complaints from residents of mosquito biting. Based on historical patterns of RRV transmission throughout Redland Shire and estimated future human population growth in areas with higher than average RRV disease incidence, it was estimated that RRV incidence rates will increase by 8% between 2001 and 2021. The use of arbitrary administrative areas that ranged in size from 4.6 to 318.3 km2 has the potential to mask any small scale heterogeneity in disease patterns. With the availability of georeferenced data sets and high-resolution imagery, it is becoming more feasible to undertake spatial analyses at relatively small scales.

Ross River Virus Risk Associated with Dispersal of Aedes (Ochlerotatus) camptorhynchus (Thomson) from Breeding Habitat into Surrounding Residential Areas: Muddy Lakes, Western Australia

“…Geographical information system (GIS) studies in southeast Queensland have shown that RRV rates are higher in areas with a greater proportion of native vegetation and wetlands21 and adult mosquito abundance 22,23. A recent study in the southwest of WA found that RRV incidence decreased with distance from a large tidal estuary with extensive mosquito breeding habitat in rural and semirural areas but found no relationship in urban areas with higher population density 24…”

Predicting the Timing and Magnitude of Tropical Mosquito Population Peaks for Maximizing Control Efficiency

“…Previous studies suggested that human infection rates are related to the appearance of large numbers of adult Ae. vigilax [8], with the recommendation that targeted control of adults in disease-prone areas could reduce the number of cases substantially. As such, identifying the environmental and biological precursors that herald the onset of peaks in mosquito abundance provide health and land-use managers the capacity to predict the timing and distribution of the most efficient and cost-effective mosquito control.…”

“…Control is often done at a local, administrative scale, with the choice of spatial configuration depending traditionally on accumulated trial-and-error knowledge rather than any systematic analysis of spatial data. Many other mosquito control studies have placed emphasis on determining the optimal spatio-temporal distribution of adult mosquitoes [8],[37],[38]. We suggest that such approaches should also be applied to Ae.…”

“…The transmission of mosquito-borne diseases is strongly linked to the abundance of the host vector [6],[8], making rigorous surveillance and control programs an essential component of disease suppression. To develop effective control measures, most studies have focused on describing and quantifying habitat associations and the particular spatio-temporal distributions of vector species.…”

Development of multiplex suspension microarrays for the detection of alphaviruses and flaviviruses of public health significance

“…Factors that could lead to increased seroprevalence include urbanisation near wetlands, increased travel, climate variability, population growth and effectiveness of vector control programs (Tong et al, 2005). Population growth in some RRV endemic regions is predicted to have a dramatic effect, with population growth in one region estimated to increase the local incidence of RRV by as much as 8% between 2000 and 2021 (Ryan et al, 2006).…”