Ross River virus (RRV) is an arthritogenic alphavirus in the family Togaviridae that causes Ross River fever, a mosquito-borne disease. The virus circulates mainly in Australia, Papua New Guinea and parts of the Pacific Islands. It is transmitted by various Aedes and Culex mosquitoes and maintained in nature by a marsupial-mosquito cycle involving wallabies and kangaroos. Human infection results from the bite of an infected mosquito.
Epidemiology and characteristics
RRV is a positive-sense, single-stranded RNA virus with an icosahedral capsid and a lipid envelope bearing E1 and E2 glycoproteins. It was first isolated from mosquitoes in the 1950s and later from humans and horses. The virus is endemic in all states of Australia and has been detected in Papua New Guinea, the Solomon Islands, Fiji, Samoa and other Pacific Islands. Transmission occurs when mosquitoes feed on viraemic reservoir hosts, typically macropods; in urban areas possums and humans can also sustain transmission. The incubation period ranges from about a week to three weeks, followed by fever, fatigue, polyarthritis, myalgia and a maculopapular rash. Arthralgia can be prolonged and some patients report symptoms lasting months. No deaths have been directly attributed to RRV infection and there is no specific antiviral therapy or licensed vaccine; management is supportive. Outbreaks are influenced by rainfall, temperature and vector abundance.
Clinical features and notable facts
Several major outbreaks have been documented. A regional epidemic between 1979 and 1980 affected Fiji, Samoa, the Cook Islands and other Pacific territories, highlighting the virus’s ability to spread beyond Australia. Large outbreaks also occurred in Australia’s 1995 wet season. Notably, more than half of symptomatic patients develop persistent joint pain that can impair daily activities, but mortality is negligible. The virus’s enzootic reservoir consists mainly of kangaroos and wallabies, and spillover to humans usually occurs near wetlands or coastal areas where mosquitoes breed. Preventive measures focus on vector control and personal protection against mosquito bites.
RRV infection is self-limiting in most cases, but the prolonged arthralgia and fatigue can be debilitating. Understanding the ecological factors governing virus circulation and maintaining mosquito control programmes are key to limiting human disease.
Related Terms: Chikungunya virus, Mayaro virus, Alphavirus, Arbovirus, Mosquito-borne disease