NAME: Ross River virus1-3.
SYNONYM OR CROSS REFERENCE: Ross River disease, Ross River fever, epidemic polyarthritis and rash, arthropod-borne viral arthritis and rash, exanthema, and RRV Footnote 1-3.
CHARACTERISTICS: Of the genus Alphavirus (group A arboviruses), a member of the Togaviridae family, and part of the Semliki complex Footnote 1. Ross River virus is a spherical (60 to 70 nm in diameter), bilayered lipid envelope with an icosahedral capsid, containing a single molecule of linear positive-sense single-stranded RNA Footnote 1.
PATHOGENICITY/TOXICITY: There are 3 major characteristics of Ross River disease, namely rheumatic symptoms, rash, and constitutional effects (e.g. myalgia, low-grade fever, fatigue, and headache). The disease has a sudden onset and the first symptom is usually classic polyarthritis with joint pain, involving the wrists, knees, ankles, fingers, elbows, toes, and tarsal joints. A rash (maculopapular, vesicular, or purpuric) is observed in 50 to 75% of patients, affecting mainly the torso and the limbs, and resolving within 7 to 10 days Footnote 2Footnote 3. Myalgia (60% of patients), fatigue, and fever are very common symptoms but do not necessarily occur at the onset of symptoms Footnote 1Footnote 2Footnote 4. Cervical lymphadenopathy is also a common sign Footnote 3.
Ross River disease usually resolves within 3 to 6 months Footnote 2Footnote 4. The arthritic form of the disease is not seen in children Footnote 1; however, maculopapular cutaneous eruptions occur in both children and adults (40% to 70% of the cases) Footnote 1.
Other manifestations include splenomegaly, haematuria, glomerulonephritis, and, in extremely rare cases, meningitis or encephalitis (3 cases reported) Footnote 2.
EPIDEMIOLOGY: Indigenous to Australia and the Western Pacific regions. Until 1979, it was only known in Australia, New Guinea, and the Solomon Islands. Later, it spread to Fiji, American Samoa, New Caledonia, and the Cook Islands in the South Pacific Footnote 1Footnote 3Footnote 4. The most common and widespread arboviral disease in Australia with 5,000 human cases reported annually Footnote 5. Epidemics tend to occur after heavy rains (most important risk factor with over 90% of major outbreaks), when the density of mosquito vectors is high. The highest incidence of disease occurs in adults 30 to 49 years of age Footnote 1Footnote 6-8. The risk for outbreaks is lower in colder countries Footnote 2. Virus isolations in humans are not routinely carried out; however, isolations in mosquitoes have helped to define the geographical distribution of different strains and their involvement with particular vectorsFootnote 7.
HOST RANGE: The virus is maintained in a primary mosquito-mammal cycle, involving macropods (kangaroos and wallabies) and possibly other marsupials (e.g. possums), flying foxes (fruit bats), and native rodents (dusky rats). A human-mosquito cycle may occur in explosive outbreaks. Horses, donkeys, dogs, cats, and birds may also act as amplifier hosts Footnote 2Footnote 9Footnote 10.
INFECTIOUS DOSE: Unknown.
COMMUNICABILITY: No evidence of direct human-to-human transmission1-3.
RESERVOIR: Non-migratory native macropods, such as kangaroos and wallabies, other marsupials including the New Holland mouse (Pseudomys novaehollandiae), flying foxes (fruit bats), horses, donkeys, possums, and three species of passerine birds Footnote 2Footnote 5Footnote 10. Transovarian transmission occurs in mosquitoes, therefore, an insect reservoir for Ross River virus is a possibility Footnote 2Footnote 3.
ZOONOSIS: Indirectly via mosquitoes.
DRUG SUSCEPTIBILITY: Unknown.
SUSCEPTIBILITY TO DISINFECTANTS: Sensitive to 70% (v/v) ethanol, sodium hypochlorite (500 to 1,000 ppm free chlorine), accelerated hydrogen peroxide, and quaternary ammonium compounds Footnote 12Footnote 13.
PHYSICAL INACTIVATION: Inactivated at temperatures above 58ºC Footnote 14.
SURVIVAL OUTSIDE HOST: Newborn mice can be used to isolate the virus, which can then be replicated in cell cultures Footnote 1.
SURVEILLANCE: For patients in non-endemic areas, diagnosis is based on symptoms, travel history, mosquito exposure, and is confirmed by serological tests. The detection of IgM in an acute-phase serum specimen through ELISA provides a presumptive diagnosis of recent infection. Generally, IgG and IgM testing is performed together. Testing of acute-phase serum and convalescent-phase serum is necessary to confirm diagnosis. The diagnostic standard is a fourfold or greater change in antibody titre as determined by haemagglutination inhibition, complement fixation, serum neutralization or ELISA Footnote 1Footnote 2Footnote 4.
Note: All diagnostic methods are not necessarily available in all countries.
FIRST AID/TREATMENT: Non-specific treatment such as non-steroidal anti-inflammatory drugs with simple analgesics may be taken for less severe disease. Physical therapy is also beneficial. Aspirin should be avoided if there is any chance of Dengue fever due to the risk of exacerbating haemorrhagic manifestations Footnote 2Footnote 5Footnote 15.
IMMUNIZATION: None available Footnote 1.
PROPHYLAXIS: In the event of an epidemic, measures should be taken to control vectors. For individual protection, repellents and other anti-mosquito measures such as light-coloured clothing may be used. To avoid further transmission, patients should be protected from mosquitoes1-3.
LABORATORY-ACQUIRED INFECTIONS: None reported to date.
SPECIAL HAZARDS: None.
RISK GROUP CLASSIFICATION: Risk Group 2.
CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures.
PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable. Eye protection must be used where there is a known or potential risk of exposure to splashes Footnote 17.
OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC). The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities Footnote 17.
SPILLS: Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply an appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up.
DISPOSAL: Decontaminate all wastes that contain or have come in contact with the infectious organism before disposing by autoclave, chemical disinfection, gamma irradiation, or incineration.
STORAGE: The infectious agent should be stored in leak-proof containers that are appropriately labelled.
REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.
UPDATED: November 2011
PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada.
Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.
Copyright © Public Health Agency of Canada, 2011 Canada