Sydney\u27s Mosquitoes: Their role as disease vectors

Mosquito-borne disease is a significant public health issue in Australia. Australia’s populous southern cities, including Sydney, are home to a wide variety of mosquito-borne pathogens, many of which are known to infect humans and our animals. The epidemiology of mosquito-borne pathogens is closely linked to the ecology of their vectors. The abundance and diversity of mosquito vector species has a huge impact on what pathogens are likely to be found in a given area. A trapping survey of mosquitoes at a variety of sites across Sydney investigated which environmental factors influenced the diversity of mosquito fauna. Sites in the middle of the city were predicted to be dominated by a different range of species to sites further west which are mainly large, vegetated, fresh water bodies. No significant difference in species diversity or abundance was found, however brackish, estuarine sites were dominated by a very different suite of mosquito species compared with the other sites. The trapping survey was repeated in February, March and April of 2015. High variability in mosquito assemblages was identified. Some species’ populations changed significantly over the three months, while others remained constant. Mosquito abundance changed differently at estuarine, freshwater and urban sites. Temporal and spatial factors interacted to influence mosquito vector diversity. The mosquito samples were tested for several different species of virus, but only one was detected: the relatively benign flavivirus, Stratford. The lack of other viruses raises the possibility that Stratford could be immunising its animal reservoir (or perhaps even human) hosts against worse flaviviruses and its presence in the environment is advantageous; an idea which certainly warrants future investigation