Arboviruses in urban and peri-urban South Australia: an eco-epidemiology approach
Broadly, my PhD research investigates how ecological factors relate to patterns of mosquito-borne virus (arbovirus) activity and human infection risk. I approach this question using a mixture of field, lab and computer modelling techniques. I hope that my research will give us insight into the factors driving mosquito-borne disease so that we can reduce or prevent human arbovirus infections.
My field work allows me to collect three main types of samples for my project: mosquitoes, viruses and blood-fed mosquitoes.
Mosquitoes: The first component of my field work is just to trap mosquitoes. I do so using CO2 and light as the attractant and a battery-powered fan to blow the mosquitoes into a container where they are trapped. I do this approximately every 2 weeks throughout the summer (Nov-May) at about 100 field sites, mostly centred around metropolitan Adelaide and the Riverlands regions. This allows me to compare the abundance and diversity of mosquitoes at the different field sites.
Virus: For Jan-April 2014, I adapted a technique developed by some colleagues in Queensland to sample the mosquitoes for infectious viruses (arboviruses) like Ross River virus. This technique takes cards, which are embedded with virus preserving chemical (FTAÂ© cards) and coats them in honey. The mosquitoes feed on the honey and in the process, spit virus onto the card (if they are infected). Then I can later test the card to determine if any of the mosquitoes were infected with an arbovirus. My work is the first to adapt this honey-baited FTAÂ© card technique to a broad-scale surveillance program.
Blood-fed mosquitoes: Throughout my field work, I have also been collecting any blood-fed mosquitoes (mosquitoes that have fed on an animal and have blood visible in their gut) so that I can find out what species the mosquito has been feeding on.
I take my mosquito samples to our lab where I count and identify the species of mosquito under a microscope. For any blood-fed mosquitoes, I extract the DNA from the blood in the mosquitoâ€™s gut and then figure out what species it came from using PCR, gel electrophoresis and genetic sequencing.
I will be using a combination of statistical modelling and Geographic Information System (GIS) spatial modelling techniques to analyse my data. I am accessing publicly available data to characterize the environments surrounding my traps. I am interested in factors like the biodiversity of animals, the density of human housing, the ratio of impermeable surface (e.g. pavement, roofs) to green space, socio-economic factors and land-use type because these may impact the prevalence of mosquito-borne diseases. I will work with this data in a computer program called ArcGISÂ© to see if I can connect the dots among mosquito species and abundances, environmental factors and virus abundance/human disease.