Simulating an invasion: unsealed water storage (rainwater tanks) and urban block design facilitate the spread of the dengue fever mosquito, Aedes aegypti, in Brisbane, Australia

Abstract

Aedes aegypti (Linnaeus) was once highly prevalent across eastern Australia, resulting in epidemics of dengue fever. Drought conditions have led to a rapid rise in semi-permanent, urban water storage containers called rainwater tanks known to be critical larval habitat for the species. The presence of these larval habitats has increased the risk of establishment of highly urbanised, invasive mosquito vectors such as Ae. aegypti . Here we use a spatially explicit network model to examine the role that unsealed rainwater tanks may play in population connectivity of an Ae. aegypti invasion in suburbs of Brisbane, a major Australian city. We characterise movement between rainwater tanks as a diffusion-like process, limited by a maximum distance of movement, average life expectancy, and a probability that Ae. aegypti will cross wide open spaces such as roads. The simulation model was run against a number of scenarios that examined population spread through the rainwater tank network based on non-compliance rates of tanks (unsealed or sealed) and road grids. We show that Ae. aegypti tank infestation and population spread was greatest in areas of high tank density and road lengths were shortest e.g. cul-de-sacs. Rainwater tank non-compliance rates of over 30% show increased connectivity when compared to less than 10%, suggesting rainwater tanks non-compliance should be maintained under this level to minimize the spread of an invading Ae. aegypti population. These results presented as risk maps of Ae. aegypti spread across Brisbane, can assist health and government authorities on where to optimally target rainwater tank surveillance and educational activities. Supplementary Information The online version contains supplementary material available at 10.1007/s10530-021-02619-z.

Projecting future risk of dengue related to hydrometeorological conditions in mainland China under climate change scenarios: a modelling study

“…Both dry and wet conditions were positively associated with dengue risk within 3 months. A modelling study 25 in Barbados that used the standardised precipitation index to explore the relationship between hydrometeorological conditions and dengue incidence also found that the relative risk of dengue was greatest under exceptionally wet conditions after 1–2 months, whereas the effect of exceptionally dry conditions was weaker and lasted longer. Various potential mechanisms have been postulated to explain the increased dengue incidence associated with hydrometeorological anomaly patterns.…”

“…The projection is largely consistent with a previous study. 25 Emphasis should therefore be placed on strengthening emergency response capacity for future prolonged droughts to cope with the accompanying increased risk of dengue.…”

Modelling the risk of Japanese encephalitis virus in Victoria, Australia, using an expert-systems approach

“…In recent years, the modelling of VBDs has advanced, employing spatial and temporal trend analysis to forewarn of potential future vector and disease expansions, particularly within various climate change scenarios [ 11 , 17 ] GIS has established itself as a vital tool in VBD modelling, facilitating the mapping of areas vulnerable to vector species proliferation and territory expansion, as delineated in various studies [ 53 – 55 ].…”

Association Between Hydrological Conditions and Dengue Fever Incidence in Coastal Southeastern China From 2013 to 2019

“… 10 Dry conditions, especially prolonged severe drought, might lead to increased use of semipermanent water storage containers, which are known to be critical larval habitats. 11 Additionally, the precipitation surplus and deficit have been associated with different timing of dengue fever occurrence. 12 , 13 Extreme precipitation may be associated with increased risk of dengue virus transmission within a few weeks, while drought may be associated with delayed risk for up to several months due to the gradual change in human coping behavior.…”

“…For example, the anomaly of wet conditions and associated precipitation may enrich the static water source, which provides the ideal breeding habitat for Aedes aegypti (Linnaeus) mosquitoes, the primary vector of dengue virus transmission . Dry conditions, especially prolonged severe drought, might lead to increased use of semipermanent water storage containers, which are known to be critical larval habitats . Additionally, the precipitation surplus and deficit have been associated with different timing of dengue fever occurrence .…”