Barmah Forest virus infection

Last updated: 31 January 2008

What is Barmah Forest virus?

Barmah Forest virus is a germ that can infect people through mosquito bites. Past infection with Barmah Forest virus may protect against future infection.

What are the symptoms?

Symptoms develop between 5-21 days, but usually between 7-10 days after being bitten by an infected mosquito. Many people infected with the virus will not develop sysmptoms. Symptoms of Barmah Forest virus infection are similar to that of Ross River virus infection, and may include:

• Flu-like symptoms, with fever chills, headache, and aches in the muscles and joints.
• Some people may develop joint swelling and stiffness, especially in the mornings.
• A rash sometimes develops, usually on the trunk or limbs. This rash usually diappears after 7 - 10 days.
• A feeling of tiredness or weakness can occur at times during the illness, which can affect both lifestyle and work performance.

How is it spread?

• The virus is spread by certain types of female mosquitoes.
• Female mosquitoes feed on animals and people. If they feed on the blood of an infected animal, the mosquito may become infected.The virus may then be passed to other animals or to people when the infected mosquito bites them while it is feeding again.
• Native animals, such as kangaroos and wallabies, are thought to be the main animals involved in the cycle of infection.
• The virus is not spread directly from one person to another.

Who is at risk?

People who are in contact with known mosquito habitats and who live in warm, humid climates near bodies of water will be most at risk of a mosquito bite and as a consequence the Barmah Forest virus.

How is it prevented?

• The key to prevention is to avoid being bitten by mosquitoes, especially in the summer and autumn months.
• Avoid being outside in the late afternoon and dusk. Mosquitoes are usually most active from 1-3 hours after sunset and again around dawn.
• When outside wear loose fitting, light coloured clothing that covers your arms and legs, and use an insect repellent that contains the chemical diethyl toluamide (DEET) or Picaridin.
• Fit fly screens to all windows, doors, and chimneys (when not in use), and keep them in good repair.
• Use an insecticide in sleeping areas, according to instructions.
• Ensure open containers of water are removed from around the home to prevent mosquitoes breeding. Cover the openings to water tanks with fine steel mesh to prevent mosquitoes from laying eggs in the tank.
• When camping, take precautions such as using flyscreens on caravans and tents, or by sleeping under mosquito proof nets.
• Take particular care while fishing, ensuring that you follow personal precautions to avoid being bitten by mosquitos.

How is it diagnosed?

Your doctor can take a blood sample and have it tested for antibodies against Barmah Forest virus infection. Two samples taken two weeks apart are required to give a clear diagnosis.

How is it treated?

• There is no specific treatment for Barmah Forest virus infection.
• Your doctor will be able to advise you on easing the discomfort of symptoms.
• Plenty of rest, along with moderate exercise, may help in your recovery.

What is the public health response?

Laboratories must notify cases of Barmah Forest virus infection to the local public health unit. Where cases occur in unexpected locations, the public health unit will investigate. Data on the occurance of Barmah Forest virus infection is used to help understand its spread.