The geography of Ross River virus infection in South Australia, 2000-2013

Abstract

Introduction Ross River virus (RRV) disease is Australia’s most common arthropod-borne disease which has an important impact on population health and productivity. The aim of this study was to identify the spatial and temporal distribution of RRV notifications during 2000–2013 in South Australia (SA). Methods The epidemiologic patterns of RRV notifications in SA from January 2000 to December 2013 were examined at a statistical local area (SLA) level. Spatial-temporal analyses were conducted using patient-reported place of exposure to characterise the recurrence of RRV infection stratified by age and sex. Results During the study period, a total of 3,687 RRV disease notifications were recorded in the state with state-wide mean annual rates of 16.8 cases per 100,000 persons and a 1:1.32 male:female ratio. The SLAs reporting cases of RRV disease exhibited spatial and temporal variation. Notified cases of RRV disease occurred more frequently in summer and autumn. A geographic expansion was observed of the area within which RRV cases occur. The comparison of age- and sex-standardised incidence rates, calculated by place of residence and patient-reported place of exposure, highlights the importance of using the latter to accurately display geospatial disease trends over time. Areas with the largest proportion of visitor cases and having the highest risk were mostly along the River Murray, which provides many vector mosquito habitats. Conclusion Although public health interventions should be considered in all SLAs where RRV occurs, we suggest that priority should be given to the Riverland areas identified as highest risk.