It is disturbing to note that since the advent of national reporting of acute encephalitis, no etiology has been established for the majority of cases diagnosed in the United States every year.1 This complacent approach to diagnosis probably stems from the apparent lack of specific therapy. Nevertheless, correct diagnosis has always been important for several reasons: for epidemiologic control of such entities as mosquito-borne encephalitis, for prognostic considerations, and so as not to miss known treatable conditions that may mimic encephalitis. In pediatrics particularly, we can illafford not to attempt to establish the specific diagnosis of encephalitis which is so prone to affect the quality of life of newborns and older children. There is even more reason today to improve our diagnostic acumen as newer methods are becoming available for the prevention and/or therapy of the second most devastating of the viral encephalitides—that due to herpes simplex viruses (HSV).
Less than a decade ago it was widely believed that HSV encephalitis in newborns and older children was an extremely rare occurrence, being a disease primarily of adults. This erroneous impression is again most likely a result of inadequate diagnosis, as well as the lack of adequate information. However, there have been many recent advances at all levels in this area.