Ross River virus found upstream

Public-health warning: Mosquitoes carrying the Ross River virus have been captured upsteam in the Georges River. Picture: Glenn Campbell

Public-health warning: Mosquitoes carrying the Ross River virus have been captured upsteam in the Georges River. Picture: Glenn Campbell

The NSW Department of Health has issued a warning to campers, fishers, swimmers and pretty much anyone who goes outdoors that mosquitoes carrying an untreatable virus have been found along the Georges River.

The Ross River virus is caused by a viral infection which is transmitted through mosquito bites and there is no specific treatment.

The warning had been initially given for areas along the river near Illawong, Lugarno, Alfords Point.

However the South Western Sydney Local Health District has already seen two cases in its hospitals.

Entomologist Dr Grant Herron, of the Elizabeth Macarthur Institute – who is a principal research scientist for the NSW Department of Primary Industries – said that it wasn’t just humans who needed to worry about mosquito-borne viruses though, it’s also livestock which are affected.

“As an agricultural research institute we’re concerned with the effects of mosquitoes on cattle,” he said.

“Insects that transfer their diseases to cattle and infect them can affect the ability to export the cattle.”

Dr Herron said mosquitoes – and biting midges, similar fly-like insects – have been moving further away from rivers as they find new places to breed.

“I’ve been seeing mosquitoes in a lot of places I don’t normally see them,” he said.

The health district’s acting public-health director, Dr Madhumati Chatterji, said that while the virus was rare, people were at risk in all parts of the state and particularly if they spent time where mosquitoes were more prevalent.

“There have only been two notifications of Ross River virus infections across the district in 2016 compared with 11 for the same period in 2015,” Dr Chatterji said.

"The best way to protect yourself from mosquito borne viruses is to avoid being bitten and use mosquito repellent containing picaridin or DEET, wearing loose-fitting clothing when outside and ensuring that your holiday accommodation has fly-screens.”

According to the local health district, mosquito trapping around the Deepwater Park area of the Georges River (surrounded by Milperra, Hammondville and Voyager Point) showed an increase in the numbers of the saltmarsh mosquito “but no identification of the virus in the mosquitoes”.

“Aedes vigilax, commonly called saltmarsh mosquitoes breed in saline and brackish water especially following floods and high tides,” Dr Chatterji said.

“People bitten by infected mosquitoes usually fall ill within three weeks and symptoms can include swollen joints, tiredness, rash and a fever.

“You should see your doctor if you experience symptoms associated with Ross River virus.

“The public health unit continues to monitor notified cases of Ross River.

“The public health unit also monitors another common mosquito-borne virus known as Barmah Forest virus infection as it has in previous years to determine numbers of cases and, in particular, whether the infection has been acquired locally or elsewhere.”

  • Ross River virus: ​health.nsw.gov.au/Infectious/factsheets/Pages/Ross-River-Fever.aspx.
  • Barmah Forest virus: as above but substitute Barmah_Forest_virus_infection.aspx.

How to avoid being bitten by mosquitoes

  1. Avoid being unprotected outside when mosquitoes are commonly around at dawn and at dusk, especially if you are holidaying in the coast or near the water.
  2. Cover up as much as possible with light-coloured, loose-fitting clothing and wear covered footwear.
  3. Apply mosquito repellent regularly to all exposed areas (as directed on the container). Repellents containing Diethyl Toluamide (DEET) or Picaridin are known to work the best.
  4. Do not use repellents on the skin of children under the age of three months.
  5. Eradicate all mosquito-breeding sites around the home. Mosquito breeding sites include pots and containers that hold water.
  6. It is recommend to install fly-screens on windows and doors of houses and to keep them in good condition.