Certain factors of climate are favorable to streptococcus respiratory diseases. In those tropical environments where hemolytic streptococcus is unusual in the throat flora, scarlet fever is unknown and rheumatic fever rare. In New York City, however, following epidemic waves of pharyngitis with hemolytic streptococcus the incidence of rheumatic fever rises precipitously. The correlation between the geographical distribution of hemolytic streptococcus and rheumatic fever is a definite one.
Furthermore, in New York City during the seasons of the year in which hemolytic streptococcus is seldom recovered from the pharynx, acute attacks of rheumatism are unusual. Corresponding to the seasonal rise in hemolytic streptococcus infections, the curve of incidence of acute rheumatism shows a similar form.
Among the children of wealthy patients, enjoying great protection, hemolytic streptococcus has been recovered infrequently from the throat, and rheumatism has not been encountered during this study. Among the poor under observation in New York City, however, the organism is found frequently in the pharyngeal flora, and rheumatic fever is common. The findings suggest that poverty and unhygienic living conditions favor both the activity of hemolytic streptococcus in the throat and the incidence of rheumatic fever.
Moreover, localized outbreaks of rheumatism have been observed frequently following epidemics of "sore throat". Bacteriological studies of these upper respiratory infections demonstrate a close relationship between the advent of hemolytic streptococcus in the throat flora and the outbreak of rheumatic fever in susceptible individuals.
In addition to these studies of streptococcus infections and their relationship to the development of rheumatic fever, observations of the rheumatic patient add further emphasis to this association. First, among a group of rheumatic children in an isolated environment, reactivation of the rheumatic process has been recognized only following the advent of hemolytic streptococcus in the throat flora.
Also, an investigation of families in which several members have rheumatic heart disease has led to the same conclusion. Recrudescences of the disease have been observed under a variety of conditions among these individuals. However, the one constant factor in the outbreaks of recrudescences in rheumatic homes is their association with family epidemics of hemolytic streptococcus infection.
Moreover, by studying rheumatic patients before, during and after transplantation to a tropical environment, it has been possible to demonstrate a close relationship between activity of the disease process and infection with hemolytic streptococcus. While the rheumatic patients remained in the tropics this organism was not recovered from the pharyngeal flora, and the disease process seemed quiescent. On return to New York City, those individuals who have escaped respiratory infection have remained symptom-free. However, of those who have contracted hemolytic streptococcus pharyngitis, each has developed a rheumatic attack within 3 weeks after infection.
Finally, extensive bacteriological studies made in ambulatory rheumatic subjects over a period of 4 years have demonstrated that the individuals who escape respiratory disease remain free of rheumatic manifestations. On the other hand, the majority of rheumatic patients who contract hemolytic streptococcus pharyngitis experience shortly afterward a definite recrudescence of their disease. In conclusion, there is a close relationship between respiratory infection with hemolytic streptococcus and activity of the rheumatic process in susceptible individuals.