Changing epidemiology of Ross river virus disease in South Australia

Objective: To investigate changes in epidemiology and symptoms of Ross River virus (RRV) disease in South Australia. Design: Longitudinal questionnaire-based survey of notified cases from one to 36 months after infection. Subjects: All patients with recent serologically confirmed RRV infection notified to the Communicable Disease Control Unit, South Australian Health Commission, between 1 October 1992 and 30 June 1993. Outcome measures: Sociodemographic data, source of infection, symptoms and ability to carry out daily activities (at onset of illness and at time of questionnaire, up to 36 months after infection), symptom duration, economic impact of the illness, case recovery time, factors predictive of delayed recovery. Results: Information was obtained on the acute illness from 698 of the 821 subjects and at 15 months after infection from 436. At 15 months, 51% of respondents still had joint pain and 45% had persistent tiredness and lethargy. Other common symptoms included myalgia (34%), lymphadenopathy (25%), headache (23%) and depression (22%). These symptoms were still common 30 months after infection. Increasing age was the only statistically significant predictor of delayed recovery. Infections were acquired across the State, away from previously recognised RRV-endemic areas. Conclusions: For many people, RRV disease is debilitating, with long term symptoms similar to those of chronic fatigue syndrome. The geographic range of the infection has expanded in SA.