Increased container-breeding mosquito risk owing to drought-induced changes in water harvesting and storage in Brisbane, Australia

Abstract

Background: Extended drought conditions in south-east Queensland during the early 2000s have resulted in a culture ofwater harvesting and legislatedwater restrictions. Aedes notoscriptus is a container-breeding mosquito vector of Ross River and Barmah Forest viruses. Methods: From 2008-2009, the larval habitats and seasonal abundance of domestic container-breeding mosquitoes were recorded from three suburbs of Brisbane. A knowledge, attitudes and practice questionnaire was administered to householders. A low-cost, desktop methodology was used to predict the proportion of shaded premises compared with front-of-property estimates. Results:We highlight changes in the frequency of container categories for A. notoscriptus as a response to human behavioural changes to drought. Garden accoutrements, discarded household items and water storage containers accounted for 66.2% (525/793) of positive containers and 77.5% (73 441/94 731) of all immature mosquitoes. Of all household premises surveyed, 52.6% (550/1046) contained rainwater tanks and 29.4% (308/ 1046) harvested water in other containers, contrasting with a previous 1995 survey where neither category was observed. Both Premise Condition Index and shade directly correlated with positive premises. Conclusions: Human response to drought has resulted in new habitats for domestic container-breeding mosquitoes. This recent trend of prolific water storage is similar to earlier years (1904-1943) in Brisbane when Aedes aegypti was present and dengue epidemics occurred. © The Author 2013. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved.