Why is there a surge in Ross River virus and what do you need to know if you’ve been infected?

Queensland is seeing a surge in Ross River virus (RRV) cases, with high numbers of mosquitos found carrying the virus when tested.

RBWH Director of Infectious Diseases Krispin Hajkowicz said the Ross River virus season is early this year due to the heavy rainfall in spring and early summer.

“Our Queensland mosquitoes are loving the hot, wet weather!” Dr Hajkowicz said.

What is Ross River virus?

Epidemic polyarthritis, commonly known as Ross River virus, is a disease spread by the bite of infected mosquitos.

“Ross River virus is only spread by blood-to-blood contact, not through other fluids, so it is not transmissible from human to human,” Dr Hajkowicz said.

Most cases occur between February and May, but it can be found in northern and central Queensland throughout the year.

Though recovery rate is 100 per cent, some people take longer than others to shake the symptoms.

What are the symptoms?

RRV causes inflammation and pain in multiple joints. Most people become unwell within three to 11 days after being bitten by an infectious mosquito.

Symptoms may include:

• Fever with joint pain and swelling (especially the finger joints, toe joints, wrists, knees and ankles) which can be severe and usually lasts for two to six weeks.
• The joint pain may be followed by a raised red rash affecting the trunk and limbs. The rash can last between one and 10 days and can be accompanied by a fever.
• Some people, especially children, may become infected without showing any symptoms.

How is it treated?

“There is no current approved antiviral treatment for RRV. Supportive care includes using anti-inflammatories like ibuprofen, and some people find swimming or hydrotherapy useful for the joint pain,” Dr Hajkowicz said.

“If people experience symptoms, they should see their GP for assessment and to arrange a blood test.”

Lots of rest is generally recommended, as well as gentle exercise in order to keep joints moving.

What steps can you take to prevent infection?

The virus is spread to humans by a number of mosquito species, especially those that breed in:

• Salty pools in mangrove and salt marshes after flooding by spring tides and heavy rains.
• Permanent bodies of fresh water.
• Containers close to homes and other human activity such as bird baths, pot plant saucers and backyard rubbish holding water.

Therefore, the best prevention is to avoid as best you can being bitten by mosquitos:

• Avoid being outside during times of heavy infestation of mosquitoes such as early evenings in the warmer months.
• Use insect repellents and wear protective, light-coloured clothing.
• Screen living and sleeping areas.
• Check your home regularly for potential mosquito breeding areas. Any uncovered water containers should be emptied regularly.

Mosquito eradication programs are the most effective way to control spread of Ross River virus. Health officers from most local councils and state health departments work together to develop and implement mosquito eradication programs.

“Scientists in Queensland are actively researching an RRV vaccine. This exciting work could see a very powerful new tool for preventing Ross River virus infection in the future,” Dr Hajkowicz said.

“There is another virus called Barmah Forest Virus that is similar to RRV and is also seeing a spike in transmission due to mosquito activity, and should be tested for simultaneously.”

Help and assistance

If you are experiencing RRV symptoms, see your GP for advice.