Ross River fever, also known as Ross River virus disease, is an infectious disease caused by the Ross River virus that is spread by mosquitoes. Affected patients experience symptoms similar to that of influenza, with fatigue and muscle aches. It is endemic in Australia, Papua New Guinea, Fiji, Samoa, Cook Islands, New Caledonia and other South Pacific islands.
The symptoms of Ross River fever may include:
- Muscle aches
- Joint inflammation
- Skin rash
- Lymph node enlargement
- Pins and needle in extremities
The polyarthritis and joint inflammation typically affects the wrist, knee, ankle, finger or toe joints. The pain and information vary in intensity and duration for different patients, lasting for a few days to a few months.
A skin rash may appear on the trunk or affected limbs of patients. It typically appears about ten days after the onset of arthritic symptoms and may continue for a week or more. Despite the name, fever is not usually a prominent symptom of the condition.
The prognosis of Ross River fever is positive with almost everyone making a full recovery. However, this can take some time and some patients experience transient symptoms for a year or more after the initial infection.
Ross River virus is an alphavirus that can be spread to humans by mosquito bites.
Researchers suspect that the virus originates from kangaroos, marsupials and other wild rodents. Mosquitoes then become infected by biting an animal with the virus and can pass it onto to a human with another bite.
The incubation period can vary from 3 to 21 days. Approximately 30% of patients develop initial symptoms 3 to 11 days after being infected with the virus and the remaining patients develop symptoms later.
A patient in an area that is commonly affected by Ross River fever can be diagnosed based on the presenting symptoms.
Blood tests can be used to detect the presence of the virus and relevant antibodies. The results reveal a current infection or if an individual has previously been affected.
Ross River virus affects populations throughout most regions of Australia and is more prevalent near waterways and coastal regions.
Particular climate conditions with heavy rainfall, flooding, high tides and high temperatures encourage the breeding of mosquitoes in the area and can sometimes lead to epidemic outbreaks of Ross River virus.
It is also endemic in Papua New Guinea, Fiji, Samoa, Cook Islands, New Caledonia and other South Pacific islands.
As Ross River virus is a vector-borne disease that is transmitted by mosquito bites, methods of preventing bites can help to reduce the risk of infection, such as:
- Loose-, light colored clothing
- Insect repellent
- Avoidance of mosquito-prone areas at dusk and dawn
- Fitting of fly screens on windows and doors of housing
- Reduction of breeding areas (stagnant water) of mosquitoes near residential areas
These methods can help to reduce the number of mosquitos in the area and the risk of being bitten by an infected mosquito.