Epidemiology and Infection

Cumulative incidence of rheumatic fever in an endemic region: a guide to the susceptibility of the population?

J. R. CARAPETIS a1c1, B. J. CURRIE a2 and J. D. MATHEWS a3
a1 University of Melbourne Department of Paediatrics, Royal Children's Hospital, Parkville, Victoria 3052, Australia
a2 Menzies School of Health Research, PO Box 41096, Casuarina, NT 0811, Australia
a3 National Centre for Disease Control, Canberra, ACT, Australia


Aboriginal Australians in northern Australia are subject to endemic infection with group A streptococci, with correspondingly high rates of acute rheumatic fever and rheumatic heart disease. For 12 communities with good ascertainment, the estimated lifetime cumulative incidence of acute rheumatic fever was approximately 5·7%, whereas over the whole population, with less adequate ascertainment, the cumulative incidence was only 2·7%. The corresponding prevalences of established rheumatic heart disease were substantially less than the cumulative incidences of acute rheumatic fever, at least in part because of poor ascertainment. The cumulative incidence of acute rheumatic fever estimates the proportion of susceptible individuals in endemically exposed populations. Our figures of 2·7–5·7% susceptible are consistent with others in the literature. Such comparisons suggest that the major part of the variation in rheumatic fever incidence between populations is due to differences in streptococcal exposure and treatment, rather than to any difference in (genetic) susceptibility.

(Accepted November 30 1999)

c1 Author for correspondence.