What is Barmah Forest infection?
Barmah Forest infection is caused by a virus of the same name that is spread by mosquitoes.
What are the symptoms?
- Fever, chills, headache and muscle pain.
- Joint swelling, stiffness and pain, especially in the mornings.
- A rash, usually on the trunk or limbs. The rash usually lasts for 7 - 10 days.
- A feeling of tiredness or weakness.
Symptoms usually develop about 7-10 days after being bitten by an infected mosquito. Many people with the infection do not develop any symptoms of the disease.
The majority of people with Barmah Forest virus infection recover completely in a few weeks. Others may experience symptoms such as joint pain and tiredness for many months.
How is it spread?
People develop Barmah Forest virus infection after being bitten by a mosquito that is infected with the virus. The virus is not spread directly from person to person.
Who is at risk?
As mosquitoes spread the infection to people, anyone bitten is at risk of infection if they are not immune. The virus is found in mosquitoes at different times of the year and the level of virus in mosquitoes varies from year to year. Warm, wet weather encourages mosquito breeding and increases the risk of infection. Most human cases occur during March and April when a higher proportion of mosquitoes carry the virus. Although coastal areas of northern NSW have the highest rates of infection, cases can also occur inland.
How is it prevented?
There is currently no vaccine against Barmah Forest virus.
To protect against mosquitoes and reduce the risk of diseases they transmit:
- Cover-up with a loose-fitting long sleeved shirt and long pants when outside
- Apply mosquito repellent to exposed skin
- Take special care during peak mosquito biting hours, especially around dawn and dusk
- Remove potential mosquito breeding sites from around the home and screen windows and doors
- Take extra precautions when travelling or camping in areas with a higher risk of mosquito-borne diseases.
For more detailed information on reducing the risk of mosquito bites at home and while travelling see the Mosquitoes are a Health Hazard fact sheet. This also includes more information on mosquito repellents.
How is it diagnosed?
Your doctor can take a blood sample and have it tested for antibodies against Barmah Forest virus. While a single test that measures IgM antibody can give some indication of a recent infection, this test is often falsely positive and does not necessarily indicate Barmah Forest virus infection. A second specimen taken 14 days later is recommended to confirm a recent infection.
How is it treated?
There is no specific treatment for Barmah Forest virus infection.
Your doctor will be able to advise you on treating the symptoms, which may include anti-inflammatory medications.
What is the public health response?
Laboratories are required to notify cases of Barmah Forest virus on diagnosis. Where cases occur in unexpected locations, the public health unit may investigate further.
For further information please call your local public health unit on 1300 066 055.