Mosquito Borne Disease in Australia

Posted on January 10, 2014 in Mosquitos, News | Share on Facebook | Twitter | Google+

Mosquito-borne viruses typically associated with tropical climates are spreading to southern parts of Australia – even as far south as Tasmania. Experts are calling on Australians to be more vigilant in regards to protection from mosquitoes.

Each year thousands of people in Australia are infected with Ross River Fever, Barmah Forest virus and Dengue Fever. The National Notifiable Disease Surveillance System records these figures and from January to September 2013 over 3000 people were infected with the Ross River virus and over 3500 people were infected with the Barmah Forest virus.

University of Sydney entomologist and mosquito researcher Dr Cameron Webb says while these viruses are usually associated with tropical far North Queensland, Ross River Fever and Barmah Forest virus are present Australia wide. Dr Webb says it is not clear why these mosquito related viruses are flaring up in cooler climates, but says climate change as well as changes in native wildlife populations may influence these outbreaks. “We are starting to see an increase in things like Ross River virus on the fringes of cities and one of the reasons for this is mosquitoes don’t hatch out of the wetlands already infected with the virus. The mosquito has to bite an infected animal, most likely a kangaroos and wallabies. So while we are doing better at conserving the wetlands around our cities and creating better conditions for our native wildlife, we are inadvertently increasing the risk of mosquito-borne in some places. We are starting to see this happen on the outskirts of Sydney and Perth in recent years”.

The symptoms of Ross River Fever generally appear about a week after being bitten by an infected mosquito. While the virus isn’t contagious between people, there is no cure or vaccination. While the Ross River and Barmah Forest viruses are not fatal they can cause joint pain, rash, fatigue and fever. These symptoms can be quite severe and last for many months. For people who have a severe case of Ross River virus it can be seriously debilitating and can have a significant impact on their lifestyle.

Queensland woman Sandra Richards was diagnosed with Ross River Fever 5 years ago and suspects she was infected after a mosquito bite in her back yard in Logan City in South East Queensland. “Our backyard has quite lush gardens and although we do have some mosquitoes we are in a typical suburban area south east Queensland and I had never even considered I could be infected with Ross River Fever. I don’t remember being bitten by a mosquito before I was diagnosed with Ross River Fever, I just started feeling very achy and lethargic, and after a couple of weeks I noticed swelling and soreness in my joints. Then I broke out in a rash from my chin to my waist. I went to the doctor thinking I had some sort of flu and was very surprised to be diagnosed with Ross River Fever. For the few weeks I felt lethargic and achy, although I started to feel better, the swelling and pain in my joints, particularly in my knees, lasted for well over a year.”

It is not known why some people have a severe case of the virus and others may not even know they have been infected. This is also the case for why some people seem more attractive to mosquitoes than others. Some researchers suspect this may have something to do with the chemicals in our breath and on our skin. Female mosquitoes are primarily attracted to the carbon dioxide we breathe out, which indicates we are warm blooded animals with the blood the female needs to fertilise her eggs. The more carbon dioxide we emit the more attractive we are to female mosquitoes looking for a blood meal (males don’t bite). Larger people tend to emit more carbon dioxide than smaller people, as do pregnant women and those who exert themselves. That’s why you can be more annoyed by mosquitoes after outdoor physical activities. It is also thought that wearing light or bright colours and certain types of perfumes may play a role in how attractive you are to mosquitoes. It’s also worth mentioning that some people have a more extreme reaction to mosquito bites than others, making it seem like they are being bothered more than other people.

At the end of the day it only takes one bite from an infected mosquito to transmit these viruses, so, avoiding bites in the best line of defence.

For more detailed information regarding Ross River Fever and Barmah Forest Virus click on the links below: