Ross river fever is caused by an arbovirus infection following mosquito bites. The most prominent clinical features are arthralgia, rashes, myalgia and fever, which respond favorably to nonsteroidal anti-inflammatory agents. The virus is native to Australia and its main reservoir hosts are marsupials.
Ross river fever (RRF) related epidemics of polyarthritis can occur in tropical parts of Australia and the western Pacific, often after heavy rain favoring the mosquito-mammal cycle of an arthropod- borne alphavirus (type A arbovirus)  . The virus resides in several reservoirs, particularly marsupials, e.g. kangaroos and wallabies  . The alphavirus genus to which arboviruses belong are small enveloped viruses with a single positive strand of RNA . More than 40 types of female mosquitoes can act as vectors  .
Clinical symptoms after the bite usually appear after an incubation period of 7-9 days following transmission of the virus by a bite from the mosquito enzootic vector (e.g., Aedes vigilax); however, development of the disease can begin within a few days or appear after as long as three weeks . Children usually present with a short-lived mild fever and malaise . In contrast, affected adults (typically in the 25-44 age range) can suddenly develop a combination of symptoms, in particular, arthralgia of the wrists, knees, and ankles, due to severe polyarthritis   , which affects the overwhelming majority of patients.
Ross river virus (RRV) from the bite becomes bound to monocytes in the blood and is then carried into the tissues. There is evidence that connective tissue in the joints infiltrated by virus-laden macrophages may be where initial replication occurs . The macrophages may then subsequently invade adjacent skeletal muscle. Through the innate immune response, the invading inflammatory macrophages cause necrosis of connective tissue and skeletal muscle   , leading to polyarthritis in the small joints, together with myalgia, an important symptom in over 60% of patients . Arthritis may persist for up to a year and can be disabling. A rash, which can be maculopapular, purpuric or vesicular may appear on the torso and limbs and is present in more than half of those affected by the virus. In some cases, it may be the only symptom . Fatigue, lethargy, and malaise with mild fever are frequent features of RRF   . Other symptoms may occur, and in addition to hematuria, splenomegaly, and glomerulonephritis, rare cases of meningitis have been reported .
The symptoms of Ross River Fever resemble those of Barmah Forest virus most closely . Direct isolation of RRV is often impractical since it soon disappears from the circulation  . A variety of serological methods have been developed to confirm RRF, with both anti-RRV immunoglobulin G (IgG) and anti-IgM being used in the tests. Although hemagglutination inhibition, complement fixation, and the neutralization procedures are available  , enzyme-linked immunosorbent assay (ELISA) against anti-RRV IgG or IgM is the preferred technique . ELISA using IgM is often used to confirm RRF in suspected new cases, and has excellent specificity and sensitivity ; however, IgM against RRV may persist following exposure, and false positives can occur because of this or the presence of other viruses, such as rubella, or autoimmune conditions  . A four-fold increase in IgG antibody titer (seroconversion) from the acute phase until convalescence two weeks later is necessary to confirm RRF  . Commercial ELISA test kits for Barmah Forrest and Ross River viruses infections are available. Reference laboratories may be needed to confirm results.