Comparison of Diagnostic Methods for Western Equine and St. Louis Encephalitis

Abstract

The usefulness of intracerebral neutralization, intraperitoneal neutralization, and complement-fixation tests for the diagnosis of human cases of western equine encephalomyelitis and St. Louis encephalitis was compared. In cases of western equine encephalomyelitis it was found that the use of all three tests assisted in making the diagnosis, but that each method failed to demonstrate a significant antibody increase in more than one-fifth of the cases. In cases of St. Louis encephalitis the intraperitoneal neutralization test was the most useful method. The intracerebral neutralization test showed an increase in antibody in only 7 of 20 cases. Complement-fixation tests were valuable in the diagnosis of both western equine encephalomyelitis and St. Louis encephalitis.