In the summer and fall months of 1935, physicians in and about Philadelphia observed that many of their patients suffered from a disease of the central nervous system which for the most part presented the following picture: The onset was usually acute, with fever, headache, nausea or vomiting forming the chief triad of symptoms. Examination disclosed some stiffness and rigidity of the neck with increased white cells in the spinal fluid, the majority of which were lymphocytes. The febrile period lasted from seven to ten days, declining by lysis and resulting in complete recovery without evidence of weakness or paralysis. Because of the type of onset, the physical changes and the termination of this disease several diagnoses were made, among which may be listed abortive poliomyelitis, encephalitis, meningismus, influenza, aseptic meningitis and the more recent disease referred to by Armstrong and Dickens1 as acute lymphocytic choriomeningitis.
Since many physicians