Ross River virus detected in record number of Queensland mosquitoes

Entomologists have detected the Ross River virus in a record-breaking number of this summer, sparking a warning for Aussies to protect themselves from mosquito bites.

Therecord-breaking number of Ross River virus detections coincides with a high number of cases among Queenslanders, Queensland Health says.

Ross River virus is spread from mosquitoes to humans, with symptoms including swollen and painful joints and rashes.

Most people who catch it will recover within a few weeks, but some experience joint pain and fatigue for months after they are first infected.

Acting chief health officer Dr Catherine McDougall said between November last year and April this year, samples from more than 1,225 mosquito traps were tested for Ross River virus, with 116 traps testing positive.

“This is the highest number of tests returning a positive result for the virus in a single season since the surveillance program started in 2016,” Dr McDougall said.

Dr McDougall said medical entomologists from Queensland Health found a significant increase in the number of mosquito samples testing positive for the virus in early February, which provided strong evidence of increased virus activity and warned of an increased risk of cases in humans.

“This is exactly what we saw – with cases starting to rapidly spike among Queenslanders by late February,” Dr McDougall said.

“This year to date, 2,065 cases of Ross River virus have been detected in humans – the highest number of cases recorded since the 2019-20 season.

“Cases peaked during the second week of March with 333 weekly cases recorded.”

Dr McDougall said the majority of cases were recorded in the state’s south east, with cases recorded in Queenslanders from November to April 2.4 times higher than the five-year average and the south east Queensland areas recording totals between six to eight times higher than average.

Queensland Health Consultant Medical Entomologist, Dr Cassie Jansen, said the department worked with local governments across Queensland to collect mosquitoes and screen them for viruses by testing their saliva.

“Queensland is one of the only places in the world that routinely tests for mosquito-borne viruses by sampling the saliva from mosquitoes,” Dr Jansen said.

Dr McDougall said Queenslanders should take measures to protect themselves from mosquito bites and mosquito-borne disease, even during winter.

“We continue to record Ross River virus among mosquito populations, so it’s always important to be vigilant against mosquito bites year-round,” she said.

“There’s no vaccine or specific antiviral treatment available for Ross River virus, so prevention is key. The most important measure you can do to protect yourself against mosquito-borne diseases is to take steps to avoid getting bitten.

“Biting can be experienced at any time of day, but some species are most active at dusk and dawn. It’s best to avoid outdoor activities when mosquitoes are most active.

“Measures to prevent mosquito bites include regularly applying insect repellent containing DEET, picardin or oil of lemon eucalyptus and wearing loose, light-coloured clothing to cover up arms, legs and feet.”