Ross River fever

Ross River fever is a mosquito-borne infectious disease caused by infection with the Ross River virus. The illness is typically characterised by an influenza-like illness and polyarthritis. The virus is endemic to Australia, Papua New Guinea, Fiji, Samoa, the Cook Islands, New Caledonia and several other islands in the South Pacific.

The first outbreak of RRF was in 1928 in the Hay and Narrandera region in New South Wales, Australia. The virus was first isolated in 1959 from a mosquito trapped along the Ross River in Townsville, Queensland. Since then, outbreaks have occurred in all Australian states, including Tasmania, and metropolitan areas. The largest outbreak occurred in 1979–1980 in the Western Pacific, and affected more than 60,000 people.

Before the identification of this infectious agent, the disease was referred to as "epidemic polyarthritis". This term was also used for a similar Australian disease caused by another mosquito-borne virus, Barmah Forest virus.

Most notifications are from Queensland, tropical Western Australia and the Northern Territory. Geographical risk factors include areas of higher rainfall and higher maximal tides. In the tropics, Ross River fever is more prevalent during the summer/autumn "wet season", particularly January—March, when mosquito populations numbers are high. In southern parts of Australia, this time period may shift to earlier in the year during spring/summer. Areas noted of common place contraction of the virus include townships and along the River Murray areas. Backwaters and Lagoons are breeding grounds for mosquitos and local medical treating facilities report higher cases than cities away from the river around the riverina areas.

Areas near suitable mosquito breeding grounds—marshes, wetlands, waterways and farms with irrigation systems—are high risk areas for outbreaks. As such, the disease is more characteristic of rural and regional areas. Infection is most common in adults aged 25–44 years old, with males and females equally affected. Ross River Fever is on the Australian Department of Health and Ageing's list of notifiable diseases.

The virus is not contagious and is spread only by mosquitoes. The main reservoir hosts are kangaroos and wallabies, although horses, possums and possibly birds and flying foxes play a role. Over 30 species have been implicated as possible vectors, but the major species for Ross River Fever are Culex annulirostris in inland areas, Aedes vigilax in northern coastal regions and Ae. camptorhynchus in southern coastal regions.

This page was last edited on 1 June 2018, at 10:02.
Reference: under CC BY-SA license.

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