Ross River fever is caused by infection with Ross River virus, one of a group of viruses called arboviruses (or arthropod-borne viruses), which are spread by the bite of infected mosquitoes.
What are the symptoms?
Many people who are infected with the virus will never develop symptoms.
- Some people will have flu-like symptoms that include fever, chills, headache and aches and pains in the muscles and joints.
- Some joints can become swollen, and joint stiffness may be particularly noticeable in the morning.
- Sometimes a rash occurs on the body, arms or legs. The rash usually disappears after 7 to 10 days.
- A general feeling of being unwell, tired or weak may also occur at times during the illness.
- Symptoms usually develop about 7-10 days after being bitten by an infected mosquito.
- The majority of people recover completely in a few weeks. Others may experience symptoms such as joint pain and tiredness for many months.
How is the virus 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 then multiplies within the mosquito and is passed to other animals or people when the mosquito feeds again.
- The number of infections tends to peak in the summer and autumn months.
- 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 infection. Ross River virus infections are the most common mosquito-borne infection in Australia, and infections occurs in many rural areas in NSW. Infections are uncommon in major cities and towns. Outbreaks can occur when local conditions of rainfall, tides and temperature promote mosquito breeding.
How is it prevented?
There is currently no vaccine against Ross River 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 factsheet. This also includes more information on mosquito repellents
How is it diagnosed?
Ross River virus infection is diagnosed by detection of antibodies against the virus in the blood. It usually requires comparison of a blood test taken early in the illness and with another sample taken two weeks later to confirm the infection.
How is it treated?
There is no specific treatment for Ross River virus infection. Your doctor will be able to advise you on medications that will help ease the discomfort of the symptoms.
What is the public health response?
Laboratories are require to notify cases of Ross River, and other mosquito-borne disease to the public health unit. Public health staff monitor the geographic spread of Ross River virus infections and provide information about avoiding mosquito-borne diseases.