The 1952 outbreak of encephalitis in California; laboratory methods for etiologic diagnosis.

The general procedures used in the diagnosis of neurotropic viral diseases are outlined and are discussed with specific reference to western equine encephalitis. Cerebrospinal fluid is considered practically worthless as a starting material, in attempts to isolate the causal agent. The material of choice in attempting to recover the virus is central nervous system tissue, available only in instances of fatal infection. In the usual case, the diagnosis depends upon serologic or immunologic methods. These methods are aimed at detecting the presence of specific antibodies and of increases in the content of antibodies in the blood during the course of the illness. The in vitro complement fixation test is considered a better diagnostic tool than the in vivo neutralization test, since rises in titer are more readily detectable by the former technique than by the latter.