Increased disease risk as mosquito numbers rise

Queenslanders are encouraged to take precautions to avoid mosquito bites this summer as we head into a period of increased risk of mosquito borne diseases.

Queensland Chief Health Officer Dr Heidi Carroll said recent wet weather has created the perfect breeding conditions for mosquitoes, which means numbers will be on the rise.

“Mosquito numbers always increase significantly in wet and warm weather, and Queenslanders need to be extra vigilant against bites starting now,” Dr Carroll said.

“With increased mosquito numbers comes increased risk of contracting mosquito-borne illnesses, such as Ross River virus and Japanese encephalitis virus (JEV)

“Biting can be experienced at any time of day, but some species are most active at dusk and dawn, so you need to be particularly vigilant at these times.”

“If you’re heading outdoors over the holiday period, such as going bushwalking, camping or enjoying backyard barbecues, you need to be taking precautions against mosquitoes.

Simple steps to prevent mosquito bites include:

• applying insect repellent to exposed skin and reapplying according to manufacturer’s instructions. Effective insect repellent against mosquitoes are preferably ones that contains DEET, Picaridin or Oil of Lemon Eucalyptus
• wearing loose, light-coloured clothing to cover up arms, legs and feet
• using insecticide sprays, insecticide-based vapour dispensing units and, if outdoors in a well-ventilated area, mosquito coils;
• ensuring your tent has screens to prevent mosquitoes entering or that you sleep under a mosquito net when camping.

Dr Carroll said it was also important to take measures around your home to prevent mosquitoes breeding and getting inside your home.

“Given all the rain recently, make sure you take a walk around your home and empty any containers holding water,” she said.

“You should also ensure flyscreens are in good order so mosquitoes can’t enter your home easily.”

Ross River virus infection is the most common mosquito-borne disease reported in Queensland.

“Typically, we see cases start increasing with the onset of rain and warm temperatures in December, before they peak in February and March,” Dr Carroll said.

“Symptoms of Ross River virus may include fever, swollen and painful joints, and a rash.”

There is no vaccine or specific antiviral treatment available for Ross River virus.

Queenslanders also needed to be mindful of JEV, a rare but serious illness which can be spread to humans by infected mosquitoes.

“We’ve been notified by New South Wales health authorities that surveillance programs have identified JEV activity among feral pig populations and mosquitoes across the state, with some activity detected near the Queensland border,” Dr Carroll said.

“This means there is likely an increased risk of JEV in Queensland.

“Residents in the Far North, Darling Downs, South West and Wide Bay regions particularly need to be vigilant as this is where JEV has previously been detected in Queensland in recent years.

“Disease caused by this virus occurs most commonly in pigs and horses but can be transmitted to humans from mosquito bites. Mosquitoes become infected after they bite infected animals.

“While most people infected with the virus are asymptomatic, it can cause fever, headaches and rashes. In severe cases, the disease can cause serious neurological illness including convulsions.”

There have been no human JEV cases in Queensland since May 2022.

JEV vaccination is recommended and available free for specific at-risk groups, such as people who work or live near a piggery or live in high-risk regional areas.

The full list of people eligible to receive free JEV vaccination is available on the Queensland Health website here: www.qld.gov.au/health/condition/infections-and-parasites/viral-infections/japanese-encephalitis