Rise in Ross River virus across SA forcing councils to control mosquito numbers

South Australians are warned to avoid exposure to mosquitoes with Ross River virus at a four-year high. There is a rise in mosquito breeding sites – which areas are most at risk?

A rise in mosquito-related illness is forcing at least one council to deploy control measures to keep the pests at bay.

According to SA Health, Ross River virus is at a four-year high, with 102 cases detected across SA in 2021, compared with 58 in 2020, 46 in 2019 and 55 in 2018.

Two cases of Barmah Forest virus were also detected last year.

Mount Barker council has been forced to deploy traps to catch and monitor mosquitoes buzzing in record numbers around local waterways and parks.

The drastic measure comes after an increase in complaints from residents who fear an onslaught of mosquitoes bring with it serious health concerns.

“The council has recently received funding from SA Health for mosquito management … which involves the use of 3D printed traps to capture mosquitoes for abundance, species identification and virus screening,” a Mount Barker District Council spokesman said.

“The council’s environmental health officers began the first mosquito trap run in December 2021 with 62 mosquitoes collected over five sites.

“No viruses were detected in the species collected (and) monthly trap setting and collection will occur through (until) April 2022.”

An increase in mosquito sightings has been attributed to current La Niña weather patterns, which have resulted in higher than average rainfall and lower temperatures across the state.

These conditions are highly conducive to mosquito breeding and can increase the risk of exposure to mosquito bites and mosquito-borne diseases.

Mt Barker District Council is conducting mosquito management across the district to help identify species and assist SA Health with virus screening.

Sixty-two mosquitoes were collected over five sites in Mt Barker during December

Regional and rural areas, especially along the River Murray, are most at risk, including the Coorong District Council area, where a trap detected 1372 mosquitoes in November 2021, compared with 315 during the same period in 2020.

A spike in mosquito activity has also been detected in Loxton Waikerie, Murray Bridge and at the Daniel Ave Wetland in northern Adelaide.

UniSA clinical and health sciences executive dean Craig Williams said Ross River virus generally peaked over summer.

“It’s a bad infection and has a big impact, especially in rural communities,” Prof Williams said.

“In addition to the other transmission and diseases that we’re currently facing – such as Covid-19 – the last thing we need is Ross River virus smashing us.

“I was up the river a few weeks ago and got absolutely smashed by mosquitoes – more than I ever have for many years.

“A lot of the mosquito breeding sites have been charged up by river water. Those are areas that are normally dry but the river is higher this year.”

A SA Health spokeswoman said as there was no vaccine or cure for mosquito-transmitted viruses, prevention was the best defence.

“It is important that people remain vigilant in protecting themselves against mosquito bites particularly during periods of warmer weather when mosquito activity is high,” she said.

“If you’re outside, apply an insect repellent containing DEET or picaridin, and try to stop mosquitoes coming indoors.

“Simple changes around the home can help to reduce and eliminate mosquitoes such as cleaning up water around the house to prevent breeding, and installing mosquito-proof mesh on doors and windows.”

SA residents can help fight the bite by joining Uni SA’s Mozzie Month in February.

The initiative relies on volunteers to set traps in their own backyard and record any sightings via the iNaturalist app.

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