Seasonal and racial incidence of infantile gastroenteritis in South Africa.

The etiology of summer diarrhea, which formerly caused extensive mortality in children living in industrialized countries, was never discovered. This condition no longer occurs in developed countries, having been replaced by winter diarrhea, which is associated with a low mortality. Summer epidemics of diarrhea still take place in black South African infants, whereas, in white South African children, the pattern of diarrhea is similar to that seen in children in industrialized countries today. In 1977-1980, the author studied the records of patients less than two years of age admitted for treatment of dehydrating diarrhea to two teaching hospitals in Johannesburg, the Johannesburg General and Baragwanath Hospitals, which serve the needs of white and black patients, respectively. The incidence of severe diarrhea (i.e., diarrhea necessitating hospitalization) showed highly significant seasonality (p less than 0.001) and distinctive patterns by race. Dehydrating diarrhea in black children was strongly associated with warm weather, while diarrhea in white children occurred more regularly throughout the year, with a peak incidence in late fall. Laboratory studies have shown that bacteria, in particular "classical" enteropathogenic Escherichia coli, are the leading cause of diarrhea in black South African children, and that diarrhea in white children is largely attributable to rotaviruses. The association of enteropathogenic E. coli with diarrhea in black children suggests that these bacteria were responsible for earlier outbreaks of summer diarrhea. The finding that the etiology of diarrhea varies according to socioeconomic class has important implications for diarrhea control programs.