Ross River virus

It is a viral disease caused by the Ross River virus and is characterised by painful or swollen joints lasting from days to months. Symptoms usually settle by themselves.

How it is spread

RRV infection cannot be spread from person to person.  The virus is transmitted to humans by the bite of an infected mosquito.

The mosquitoes present in the Northern Territory (NT) that can spread the virus are Culex annulirostris (common banded mosquito), Aedes vigilax (salt marsh mosquito), Aedes normanensis (flood water mosquito) and Aedes notoscriptus (backyard mosquito).

Many people, particularly children, even if bitten by an infected mosquito, do not develop any symptoms of the disease.

Where and when is the virus 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 inclusive with the highest risk period in January when large numbers of mosquitoes result from either high tides or increased rainfall.

Humid conditions enable mosquitoes to live longer, which allows more chance for a mosquito to pick up a virus from the animal reservoir (usually marsupials such as kangaroos and wallabies) and to live long enough for it to multiply and infect the mosquito and then pass it on to humans in saliva when it bites.

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 infection 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.

Treatment

RRV infection is diagnosed by a blood test. There is no vaccine to prevent RRV infection, and 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.

Prevention

Try to reduce the number of places on your property where mosquitoes can breed.

Any pools of water, even if tiny, can provide breeding sites for mosquitoes.

The only protection from RRV is to avoid being bitten by mosquitoes.

Personal protective measures:

• stay indoors when mosquitoes are most active, from just before, until 2 hours after sunset
• ensure flyscreens in houses or caravans are in good condition
• if camping out sleep in a mosquito-proof tent or under a mosquito net. Repellents only protect against mosquito bites for up to four hours, not all night
• avoid scents on the body, e.g. perfume, deodorants, and sweat, since these can attract mosquitoes
• use personal repellents containing DEET, picaridin or PMD (extract of lemon eucalypt) on areas of exposed skin in combination with protective clothing
• use electric insecticide devices using repellent treated pads in indoor or enclosed areas
• use mosquito coils, or candle heated or gas operated devices using insecticide treated pads for patio and veranda or relatively sheltered or low wind outdoor situations.

For more information go to protecting yourself against mosquitoes.

Other languages

Ross River virus Arabic translation  (Adobe PDF document - 168KB)
Ross River virus Bahasa Indonesian translation  (Adobe PDF document - 30KB)
Ross River virus Dari translation  (Adobe PDF document - 109KB)
Ross River virus Farsi translation  (Adobe PDF document - 198KB)
Ross River virus Kurdish translation  (Adobe PDF document - 94KB)

Information for health professionals

To find out more go to the NT Health website.

Contact

For more information contact your nearest Centre for Disease Control.