In order to recognize rheumatic fever and to give proper treatment to a patient, it is of value first of all to understand modern concepts regarding the etiology of this disease and more specifically the epidemiology of streptococcic disease. Nearly all authorities are now convinced of the importance of streptococcic disease in initiating the onset of rheumatic fever; however, the exact mode of production of rheumatic fever by the streptococcic organism or its by-products is not clearly understood. Factors in addition to streptococcic disease would also appear to be of importance in the development of rheumatic fever. Here likewise the relationship is not entirely clear. All of the factors, listed in the order of their apparent importance, are streptococcic infection, hereditary predisposition, environment (stress), endocrine status (adrenal), and dietary intake and nutritional status.
Rheumatic fever occurs at all ages but has its peak incidence at 9 years of age
Adams FH. NEWER CONCEPTS IN THE DIAGNOSIS AND TREATMENT OF RHEUMATIC FEVER. JAMA. 1954;156(14):1319-1320. doi:10.1001/jama.1954.02950140019007