EPIDEMIC ENCEPHALITIS AND SIMPLE HERPES.

The purpose of this paper is to explain the state of our knowledge of the etiology of epidemic encephalitis, and especially to draw a line of demarcation between the established virus of simple herpes and the hypothetical virus of epidemic encephalitis. It had already been shown that the experimental observations on rabbits do no suffice to prove the identity of the herpes with the encephalitis virus. The discussion of the subject in this paper shows that identity cannot be postulated on the basis of the performed guinea pig experiments. Attention has been drawn to the significant fact that there is lack of harmony in the positive results of those investigators who believe that the incitants of epidemic encephalitis have been discovered. An attempt has been made to attribute some of the discrepancies reported by these investigators either to accidental and contaminating microbic agents, or to the uncovering of virulent agents preexisting in a latent state in the animals employed for inoculation, the existence of which was not previously known or suspected. Since past experience leads us to believe in a single incitant for widespread epidemic diseases, it is probable that, when certainly discovered, the microbe of epidemic encephalitis will prove to be simple and not multiple. The direct corollary to this point of view is that up to the present, the etiology of epidemic encephalitis has not been determined.