Epidemiology of rheumatic fever

Abstract

Certain facets of the epidemiology of rheumatic fever are not clear. The correlation of group A beta hemolytic streptococcal infections and rheumatic fever is established; in all probability this is the specific etiologic agent in rheumatic fever. The latter then may prove to be a clinical manifestation of a certain phase (nonsuppurative and late) of streptococcal infection, rather than a disease entity in itself. In numerous respects the epidemiology of rheumatic fever mimics that of streptococcal infections. Some conditioning of tissue by infection, especially through antigen-antibody interaction or hypersensitivity, is probably involved in the basic pathogenesis of rheumatic fever. 1,48,49 Most group A streptococci very likely furnish the antigenic stimuli concerned in the development of this pathologic process and this may prove to be their rheumatogenic property. The response of the immunologic mechanisms of the host governs in some way the initiation and progression of the histopathologic changes which occur. Alterations in the immune response are probably precursors to the evolution of events in the pathogenesis of rheumatic fever. Other factors may play an important part in the epidemiology of this disease. The inherited susceptibility to rheumatic fever has been emphasized. The influence of age on the attack rate of rheumatic fever may reflect only the stage of maturity of the immune mechanism of the host. Environmental factors appear to affect primarily the epidemiology of rheumatic fever only as they influence conditions which enhance the spread of streptococcal infections, particularly in streptococcal epidemics. The variability of host factors involving susceptibility and resistance to streptococci, most of which may prove to be “rheumatogenic,” make it exceedingly difficult to clarify the role of these factors in the epidemiology and pathogenesis of rheumatic fever. However, to set the stage for the possible development of rheumatic fever a susceptible individual must have been challenged by one of the various strains of group A streptococci. Whether or not a sequence of events follows which leads to rheumatic fever is dependent upon a number of variable and unknown factors.