Ross River virus
Ross River virus (RRV) is a viral disease that can cause painful or swollen joints lasting from days to months.
Symptoms usually settle by themselves.
Where it's found
RRV is found throughout Australia, Papua New Guinea, parts of Indonesia and the western Pacific Islands.
In the NT, the main risk season is from December to March. The highest risk period is in January when there are large numbers of mosquitoes due to high tides or increased rainfall.
Humid conditions also allow mosquitoes to live longer, which allows them more chance to:
- pick up RRV from an animal reservoir (usually marsupials such as kangaroos and wallabies) and
- live long enough to multiply and then pass it on to humans in saliva when it bites.
How it spreads
RRV is transmitted to humans by the bite of an infected mosquito.
It cannot spread from person to person.
The mosquitoes that can spread the virus in the NT are:
- culex annulirostris (common banded mosquito)
- aedes vigilax (salt marsh mosquito)
- aedes normanensis (flood water mosquito)
- aedes notoscriptus (backyard mosquito).
Symptoms
Symptoms vary from person to person and may appear from 3 days to 3 weeks after being bitten, most commonly within 7 to 14 days.
The illness generally begins with painful (sometimes swollen) joints and muscle and tendon pain. The most commonly affected joints are the ankles, fingers, knees and wrists. The pain usually develops rapidly, may be intense, and may be more severe in different joints at different times.
Other symptoms include a raised red rash affecting mostly limbs and trunk, fever, fatigue, headache, light intolerance and swollen glands. Less common symptoms include sore eyes and throat, nausea and tingling in the palms of the hands or soles of the feet.
Fever, nausea and the skin rash usually disappear within the first 1 or 2 weeks of illness. Joint, muscle and tendon pain may last much longer, and can be distressing. Some people also have lingering fatigue, lethargy and depression.
Symptoms subside eventually and leave few or no after-effects. It is not possible at present to say how long an individual person will take to get better.
Some adults with RRV recover within 2 to 6 weeks of onset of the illness and most people will progressively improve over 3 to 6 months. A minority of people (about 15%) will still be unwell at 3 months, and at 6 months about 5% will have persistent joint pains and lethargy.
A small minority (up to 2%) of people may have residual symptoms after a year. In general, people with symptoms after a year should be re-investigated and other forms of arthritis considered.
People with long-term symptoms are not sick all the time. By 3 months, many people experience some days when they are well and others when they are not, and as time goes by, the latter become less frequent, but symptoms may recur suddenly and without warning.
As a rule, once you’ve had RRV once, you won’t get it again. However, there have been a few rare cases of people developing RRV more than once in their lifetime.
Children tend to experience milder symptoms of shorter duration than adults.
Diagnosis
RRV infection is diagnosed by a blood test.
Treatment
There is no medical cure for the disease.
Medical treatment is aimed at easing joint pains and swelling, and minimising fatigue and lethargy.
For some people, simple pain-killers like aspirin or paracetamol are sufficient. Others will require stronger medications to ease the inflammation.
Emotional stress, physical fatigue and alcohol may cause symptoms to worsen or to last longer.