Following Sainton,1 we may define this disease as "a toxic, infectious, epidemic syndrome, characterized clinically by the triad lethargy, ocular palsies, and a febrile state; and anatomically by a more or less diffuse encephalitis, most marked in the gray matter of the midbrain."
The term "lethargic encephalitis," proposed by Economo2 in 1917, is descriptive of the most important clinical and anatomic features; but it is illogical, as the patient, not the encephalitis, is lethargic. As there is no other form of encephalitis known to occur epidemically, it would appear sufficiently distinctive to designate the disease as "epidemic encephalitis." The term "sleeping sickness" has already been appropriated for the endemic trypanosomiasis of Africa, and should, therefore, be avoided in connection with the present affection. "Nona," a meaningless word used for a similar disease in 1890, has the advantage of being short as well as noncommittal, and should perhaps be