ROSS RIVER VIRUS-INFECTION ON THE NORTH COAST OF NEW-SOUTH-WALES

A retrospective follow-up survey was undertaken of residents of the No rth Coast of New South Wales infected with Ross River virus in 1992. T he aims of the study were to describe the epidemiology and acute sympt omatology of Ross River virus infection, its natural history during th e first 12 months of infection, and its effects on those infected. Que stionnaires were distributed to both cases and their medical practitio ners. Of 129 people infected, aged between six and 85 years, 81 (63 pe r cent) were male and 48 (37 per cent) were female. The peak age-speci fic incidence was in the age group 50 to 59 years. The most common sym ptoms were arthralgia (95 per cent) and tiredness (91 per cent). Over 60 per cent took time off work. At 12 months follow-up, over 50 per ce nt reported persistent arthralgia, 35 per cent reported persistent tir edness and 15 per cent were still unable to carry out their normal act ivities. The median duration of symptoms was in the range 7 to 12 mont hs, and of incapacity was in the range five weeks to three months. The re were some differences from previous reports of Ross River virus out breaks, in the incidence of major symptoms and the duration of illness and incapacity. These are likely to be at least partly due to inconsi stent measurement methods. In this study, there were systematic differ ences between medical practitioners' and patients' estimates of period s of incapacity. Previous estimates of the direct economic costs and i ndirect human costs of infection based on data obtained from medical p ractitioners, although alarming, are almost certainly underestimates.