Scientists are asking people to check their rainwater tanks, after new research revealed unsealed and damaged tanks could expose millions of Australians to the risk of mosquito-borne infectious diseases like dengue fever.
The Aedes aegypti mosquito infects hundreds of millions of people across the globe each year with dengue fever, Zika virus, chikungunya and yellow fever. In Australia the mosquito is found mostly in North Queensland, but it also exists in a number of towns in the Wide Bay region closer to Brisbane.
"Previous studies had suggested that conditions in Brisbane were inhospitable for the species during winter, but our findings show that rainwater tanks could provide year-long protection for the Aedes aegypti mosquito in Brisbane and other sub-tropical areas of Australia," said CSIRO scientist Dr Brendan Trewin.
It is believed that more than 40 per cent of Brisbane properties now have rainwater tanks, though this number could be much higher as there is no formal registration or monitoring procedure.
"The last time Brisbane had significant Aedes aegypti and dengue epidemics they also had a lot of unsealed rainwater tanks, and our research suggests that one of the keys to driving the disease-carrying mosquito out of the city was the decision to remove these tanks in the 1950s," Dr Trewin said.
"We are not suggesting that rainwater tanks should be removed, but we think it is important for people to be aware that if their rainwater tanks are not maintained properly, large areas of Southern Australia could see the return of the Aedes aegypti and other exotic disease vectors, bringing with them potentially serious implications for public health."
Dr Trewin said many people were unknowingly adding to the risk by making modifications to their tank like removing the sieve that collects leaves from the roof and gutters, or adding modified downpipes.
"Biosecurity is just as important in the backyard, as it is at the border. People need to check to make sure their water tanks are compliant, fully sealed and not capable of allowing mosquitoes in or out," he said.
Researchers measured mosquito survival and development during simulated Brisbane winter conditions in rainwater tanks and buckets and found that 70 per cent of mosquito larvae survived to adulthood in water tanks, and 50 per cent in buckets.
QIMR Berghofer Medical Research Institute Associate Professor Greg Devine said each year hundreds of people arrived in Australia infected with dengue and other infectious diseases which could be transmitted by the Aedes aegypti.
"These non-compliant water tanks pose a real risk of becoming Aedes aegypti habitats and breeding sites, which could lead to outbreaks of dengue, chikungunya and Zika to a population that has no immunity to these diseases," Associate Professor Devine said.
The results of the research have been published in the journal PLOS One.
How to mosquito proof your tank:
- Check there are sieves at the entrance and overflow and there are no gaps
- Check for cracks in plastic tanks
- Make sure the sieves aren't rusting and there are no holes
- Mosquitoes feed on rotten leaves so keep gutters leaf free
- Check that first flush devices are draining
