Spatio-Temporal Analysis of Dengue Cases in Queensland, Australia, 2010-2015

Abstract

Dengue, an acute infectious disease, is a public health concern in northern Queensland, Australia characterised by annual outbreaks. This study explored spatio-temporal characteristics of dengue cases in Queensland, to identify high-risk areas at fine spatial scale and thereby help in planning resource allocation for dengue control measures. Notifications of dengue cases for Queensland at statistical local area (SLA) level were obtained from Queensland Health for the period 2010 to 2015. Spatio-temporal analysis was performed, including plotting of seasonal distribution and decomposition of cases, using linear regression models and creating choropleth maps of cumulative incidence. The space-time scan statistic (SaT Scan) and a geographical information system were used to identify and visualise the space-time clusters of dengue cases. A total of 1773 dengue cases with 632 (35.65%) autochthonous cases and 1141 (64.35%) overseas cases were reported in Queensland during the study period. Both autochthonous and overseas cases occurred more frequently in autumn and showed a geographically expanding trend over the study period. The most likely cluster of autochthonous cases (RR=54.52, p<0.001) contained 50 SLAs in the north-east region of the state around Cairns occurred during 2013-2015. A cluster of overseas cases (RR of 60.81, p<0.001) occurred in Herston (Brisbane) during 2012 to 2013. These results could be useful in directing future investigations on risk factors and effective interventions in these high-risk areas.