Acute glomerulonephritis in siblings has rarely been reported,1 which is rather surprising in view of the high incidence of infections of the upper respiratory tract and particularly in view of the known contagiousness of these infections. Hayman and Martin found that infections of the upper respiratory tract, including scarlet fever, preceded the onset of acute nephritis in 69 per cent of 976 cases which they studied.2
Löhlein, in 1907, was the first to furnish evidence to show that acute glomerulonephritis most often followed streptococcic infections.3 Since then others have substantiated his observations concerning the etiologic role of the streptococci.4 Sensitivity to bacterial products may also be a factor in the production of nephritis.5
The interval between the onset of the causative infection and the appearance of symptoms of nephritis varies from two days to four weeks.6 If the onset is sudden, i. e. if