The spatial distribution of ross river virus infections in Brisbane: Significance of residential location and relationships with vegetation types.

For the study area of Brisbane City (population 800,000), Australia, 2160 cases of Ross River virus (RRv) infections from the years 1991 to 1996 were geocoded. Their spatial distribution was investigated using census data at the suburb level (162 units). Infection rates have been calculated and adjusted to the age distribution within each suburb. Signed chi-square tests showed that a large number of suburbs has significantly high or low infection rates. Using Principal Component Factor analysis and regression, a relationship was shown between the proportion of wetlands and bushland in a suburb and the infection rate of RRv. Although flight ranges of up to 50 km have been reported for the major vector speciesAedes vigilax (Skuse), this study indicated that RRv infection risk is significantly high relatively close to mosquito habitats. There were significant differences in the infection rate of RRv between years, however the spatial associations did not appear to differ.