Worrying trend in do-it-yourself mosquito repellents in Grampians

Grampians Public Health Unit chief strategy and regions officer Rob Grenfell, who is also a health and biosecurity director for the CSIRO, said the health service had been alerted to the worrying trend amid this season's swarming mosquito bombardment.

Flooding and a wet spring, followed by warm weather, had mosquito numbers booming with heightened risks of mosquito-borne diseases Ross River fever and Barmah Forest virus sparking public health warnings in regional Victoria.

Dr Grenfell said living in rural and regional areas, people tended to have more access to lots of chemicals and such high numbers of mosquitoes had people reaching for whatever they heard might reduce bites. This included the use of insect repellents mixed with rubbing alcohol.

"All mosquito repellents in Australia, particularly with active ingredients, are under the watchful eye of the TGA [Therapeutic Goods Administration]. The problem with making home brews means you cannot be guaranteed safe levels in blends," Dr Grenfell said.

"Insect repellents you can buy in supermarkets and pharmacies are safe for children and adults. Commercial products come with warnings and suggestions, particularly for use on children and babies.

"There is a lot of folklore for home remedies, and I wish I could tell you they were true but we know they don't work because of an enormous amount of research for what repels mosquitoes."

Dr Grenfell said mosquitoes had plagued Australia "forever" with Indigenous Australians also known to try repelling methods, such as smoke. He said other natural methods such as essential oils, including lavender and citronella, and taking Vitamin B or eating lots of garlic also had been scientifically tested and shown not to stop bites.

But doing all things necessary - not relying on one method - was important.

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Dr Grenfell said planting pyrethrum daisies near windows could help deter and decrease pests, including mosquitoes, but would not stop them completely. Similarly, burning citronella candles could help clear mosquito numbers.

Other bite prevention methods are: ensuring screen windows are intact; bed netting when needed (such as camping); using strong repellent containing diethyltoluamide (DEET) or picaridin; wear insect repellent-treated clothing; wearing loose, light-coloured clothing; and, avoid peak active times at dusk and dawn. People are also urged to remove any stagnant water.

"People need to take an approach with a lot of combined methods to prevent bites," Dr Grenfell said. "If you can't secure your houses, which is an issue for a lot of people in rentals, use netting over beds and if using netting for babies, make sure it is safe and secure and not possible for babies to get entangled.

"Our youngest little people are just as prone to bites."

Dr Grenfell said Queensland and New South Wales had identified a case of Japanese encephalitis. While active mosquito monitoring in Victoria has not shown this yet, other fever-like diseases from Ross River fever and Barmah Forest virus were spreading.

For medical advice on do-it-yourself repellents, contact Poisons Information Centre on 13 11 26.

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