We analyzed hospitalizations in England from April 1, 1989,to March 31, 1998, and identified approximately 700 cases, 46fatal, from viral encephalitis that occurred during each year;most (60%) were of unknown etiology. Of cases with a diagno-sis, the largest proportion was herpes simplex encephalitis.Using normal and Poisson regression, we identified six possi-ble clusters of unknown etiology. Over 75% of hospitalizationsare not reported through the routine laboratory and clinical noti-fication systems, resulting in underdiagnosis of viral encephali-tis in England. Current surveillance greatly underascertainsincidence of the disease and existence of clusters; in general,outbreaks are undetected. Surveillance systems must beadapted to detect major changes in epidemiology so that timelycontrol measures can be implemented
展开▼
