Introduction

Ross River virus is a virus that causes an infectious disease known as Ross River Fever (aka endemic polyarthritis). It is spread by mosquitos, seen throughout Australia, most commonly in Queensland, as well as Papua New Guinea and other islands in the pacific.

Ross River fever is a debilitating but rarely dangerous illness, characterised by polyarthritis (95%), rash (50%), and tiredness or lethargy.

It can occur at any time of year in most of Australia, but most cases occur between February and May.

Diagnosis is confirmed with serology. There is no specific treatment, and symptom management is all that is required. Symptoms may persist for many months, and a post infective chronic fatigue (similar to EBV or CMV) is seen in about 10% of cases.

It is clinically similar to Barmah Forest Virus, although Ross River Fever typically is a more debilitating and longer lasting illness.

In indigenous it is important to consider a diagnosis of Rheumatic fever in patients presenting with fevers and polymyalgia.

Presentation

  • Incubation period 3-11 days
  • Arthralgia – 95%
    • Can be severe
    • Typical duration is 6-12 weeks
    • In most cases it has resolved by 7 months
  • Rash – 50%
    • Between 1-10 days after the onset of joint pains
    • Mainly trunk and limbs
    • Rash lasts up to 10 days, usually less
  • Fever
    • Often comes with the rash
  • Chronic fatigue is present in about 10% of cases at one year after symptom onset

Diagnosis

  • Confirmed with serological testing
  • IgM is present 7 days after infection and remains positive for months or years

Transmission

  • Mosquito bites only
  • Cannot spread directly from person to person
  • Spread by multiple mosquito species
  • Main reservoir of disease is in animals
    • Mainly kangaroos and wallabies, but up to 30 species are implicated
  • Be wary of mosquito breeding grounds in standing water – e.g. salt marshes, mangroves, and in standing water around the house – such as bird baths, plant pots and in buckets and containers around the house
  • Mainly occurs in tropical areas in Queensland and the Northern Territory, but also frequently reports in NSW and Western Australia
  • Much more common in rural areas

Prevention

  • Avoid getting bitten by mosquitos!
    • Most bites occur in the early evening in warmer months
    • Use insect repellents
    • Wear light coloured clothing
    • Use fly screens on windows and doors
    • Check around the home for potential mosquito breeding areas
  • Controlling mosquito breeding areas by local councils is effective at controlling outbreaks

References

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