Final opinion regarding the exact nature of the encephalitis epidemic in St. Louis City and County in the late summer of 1933 and regarding its pathogenesis and spread must await further study, although some information has been obtained that may give more definite trends to the estimation on these points.
TYPE OF DISEASE
In recent years, encephalitis, like poliomyelitis, has been always present, and at every season, in communities of large size. A survey of the more important cities of the United States reveals that many of the cases currently being reported as epidemic or lethargic encephalitis lack the characteristics either of the disease as seen in St. Louis in 1933 or of the disease as originally called lethargic encephalitis by von Economo or epidemic encephalitis since Economo's first description. Some of these current cases prove to be some other condition in their further course; in others, on account of
J. P. LEAKE, E. K. MUSSON, H. D. CHOPE. EPIDEMIOLOGY OF EPIDEMIC ENCEPHALITIS, ST. LOUIS TYPE. JAMA. 1934;103(10):728–731. doi:10.1001/jama.1934.02750360004003