The elimination of the dengue vector, Aedes aegypti, from Brisbane, Australia: The role of surveillance, larval habitat removal and policy.

Brendan J Trewin,Jonathan M Darbro,Cassie C Jansen,Tim P Hurst,Myron P Zalucki,Nancy A Schellhorn,Gregor J Devine,Pattamaporn Kittayapong

doi:10.1371/journal.pntd.0005848

Abstract

Aedes aegypti (L.) (Diptera: Culicidae) is a highly invasive mosquito whose global distribution has fluctuated dramatically over the last 100 years. In Australia the distribution of Ae. aegypti once spanned the eastern seaboard, for 3,000 km north to south. However, during the 1900s this distribution markedly reduced and the mosquito disappeared from its southern range. Numerous hypotheses have been proffered for this retraction, however quantitative evidence of the mechanisms driving the disappearance are lacking. We examine historical records during the period when Ae. aegypti disappeared from Brisbane, the largest population centre in Queensland, Australia. In particular, we focus on the targeted management of Ae. aegypti by government authorities, that led to local elimination, something rarely observed in large cities. Numerous factors are likely to be responsible including the removal of larval habitat, especially domestic rainwater tanks, in combination with increased mosquito surveillance and regulatory enforcement. This account of historical events as they pertain to the elimination of Ae. aegypti from Brisbane, will inform assessments of the risks posed by recent human responses to climate change and the reintroduction of 300,000 rainwater tanks into the State over the past decade.

Highlights

Dengue fever is the 21st Century’s most important mosquito-borne viral illness, exerting a huge economic and health burden in the tropics and sub-tropics [1]
We examined the historical role that water storage practices and the enforcement of antimosquito regulations played in the elimination of Aedes aegypti from Brisbane, a major urban centre in Australia
What evidence is there to test the hypothesis that Ae. aegypti is still present in Brisbane? Secondly, if local elimination occurred, what quantifiable evidence was there to test the hypotheses that the removal of rainwater tanks contributed to the elimination of the species? what were the drivers that led to the removal of rainwater tank infrastructure? To answer these questions, we created a time-line of events and linked direct observations recorded by government surveillance and regulatory enforcement

Summary

Introduction

Dengue fever is the 21st Century’s most important mosquito-borne viral illness, exerting a huge economic and health burden in the tropics and sub-tropics [1]. The incidence of dengue has increased 30 fold over the past five decades and the disease is estimated to affect up to 390 million people each year [1, 2]. This increase in prevalence is due to substantial growth in urbanization, trade, international travel, and the spread of its major vectors [3]. A rise in imported cases of mosquito borne diseases into Australia has increased the risk of local transmission of dengue, chikungunya and Zika viruses in all regions where the primary vector, Aedes aegypti (L.) is present [9, 10]

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Conclusion