Spreading dryland salinity significantly affects WA’s agriculture and the environment and may also impact on human health, due to a mosquito responsible for transmitting Ross River Virus (RRV).
Adults infected with RRV experience symptoms similar to arthritis and chronic fatigue syndrome, which include muscle and joint pains, swelling, rashes, fever and fatigue. These symptoms may last for months to years.
In nature, RRV is passed back and forth between hosts, with humans only infected if bitten by a mosquito carrying the virus.
The mosquito vector of RRV, Aedes camptorhynchus, breeds in saline water and Scott Carver, a PhD student at The University of Western Australia (UWA), is studying how spreading dryland salinity in the grainbelt will affect mosquito populations and the potential for occurrence of RRV.
His thesis is jointly supervised by Dr Helen Spafford, Senior Lecturer and Dr Andrew Storey, Adjunct Senior Lecturer, both of the School of Animal Biology, Faculty of Natural and Agricultural Sciences, UWA and Professor Philip Weinstein at the School of Population Health, Faculty of Medicine, Dentistry and Health Sciences, UWA.
According to Mr Carver, the mosquito vector of RRV is more abundant in areas affected by dryland salinity.
"This mosquito tolerates saline water and as salinity increases other insects which may naturally regulate the mosquito’s abundance, by predation or competition for food, are less abundant," he said.
Mr Carver indicated that about 1.5 million hectares are currently affected by dryland salinity in WA’s grainbelt and this is expected to expand to as much as five million hectares by 2050.
"Presently, few cases of RRV occur in the grainbelt and those that do usually coincide with epidemics in the Peel Region.
"We suspect the virus is periodically introduced into the grainbelt by mosquitoes being blown inland or infected people moving between the Peel and the grainbelt.
"However, transmission of the virus doesn’t seem to last long, so the everyday risk to people is currently very low," he said.
"But there is the risk that with increasing dryland salinity, the mosquito vector for RRV will increase in abundance and range.
"This research will contribute pro-actively to understanding RRV in the grainbelt and help manage the disease if and when outbreaks occur," Mr Carver said.
RRV cycles between mosquitoes and vertebrates, with kangaroos thought to be a carrier, but there may be many other mammals involved.
Mr Carver said his study fits within an Ecosystem Distress Syndrome (EDS) model, which is
characterised by a range of adverse outcomes and one outcome applied to dryland salinity is the implications for human health.
(Source: The University of Western Australia: July 2008)