Ross River Fever

Ross River Fever is viral disease, transmitted to humans by the bite of a mosquito. It is a vector-borne disease. The virus is endemic to Australia, Papua New Guinea and several pacific islands (Fiji, Samoa, New Caledonia and Cook Islands).

Ross River Fever is the most common arboviral disease (diseases transmitted by insects) in Australia.  It can also be transmitted by transfusions and from the mother to child during pregnancy.

The disease is notifiable in Australia and more than 3,000 cases are reported annually. It causes serious morbidity but isn’t fatal. The post viral fatigue can be quite incapacitating in some cases, lasting many months. Treatment can only be directed towards the relief of symptoms.

The is no vaccine for Ross River Fever.

The disease was originally described as “epidemic polyarthritis” with case descriptions going as far back as the late 1920’s.  In 1959 a virus was isolated from mosquitoes trapped in the Ross River and epidemic polyarthritis became Ross River Fever or Ross River Virus Disease (RRVD).

Two determinants contribute to the risk of RRVD.

• Local mosquitoes known to carry the virus (Aedes camptorhynchus, Aedes vigilax, Aedes notoscriptus, Culex annulorostris,) More than 30 species are known to be carriers of the virus.
• Presence of vertebrate reservoirs for the disease (kangaroos and wallabies in rural areas and horses and possums in urban areas)

The mosquitoes pick up the virus from a vertebrate host and transmit it to humans. In large outbreaks the virus can be transmitted by mosquitoes from human to human like dengue fever.

Environmental conditions are major determinants of risk. RRVD outbreaks often follow periods of high rainfall and flooding (both coastal and inland).  The viruses replicate best at temperatures between 24 and 27C.

More information is available from most State health departments. See NSW & QLD Government fact sheets.

Case reports on RRVD are common in returning travellers from Australia, PNG and the pacific region. It has been reported in all states of Australia.

Most notifications come from Queensland. There have been 223 notifications in Queensland to March 30, 2025, year to date with 3,360 across Australia for 12 months to February 2, 2025.

RRVD should always be suspected along with dengue fever in a traveller with a history of inflamed joints and fever who has visited an area or risk either in Australia or overseas.

Individuals at most risk are those intending to do outdoor activities such as camping, fishing and hiking.  The mosquitoes are most active early morning and at dusk.

Reduce mosquito exposure by modifying activities, wearing light-coloured clothing that covers arms and legs, and using permethrin-impregnated clothing or bedding if needed. Avoid highly scented perfumes and toiletries. Sleep under permethrin-treated mosquito nets and use ceiling fans or air-conditioning when available. Remove standing water around accommodation (e.g., cans, tyres, buckets) to eliminate breeding sites. Apply mosquito repellents on exposed skin and use insecticide aerosols, coils, or similar products in the environment.

Repellents containing DEET are recommended. Higher concentrations provide longer protection, but concentrations above 50% offer no extra benefit. DEET should be applied lightly, avoided on cuts, and washed off indoors. Lower-strength DEET products (around 10%) are preferred for children.

Picaridin (20–25%) is a non-toxic alternative to DEET, providing 4–6 hours of protection and suitable for individuals aged 2 years and older.

See our guide on mosquito avoidance measures.