Epidemiology and pathogenesis of clinical spectrum of Japanese encephalitis

Abstract

Japanese encephalitis (JE) is the most important endemic encephalitis in the world affecting over 50,000 patients annually in Southeast Asia. One-third of JE patients die and half of the survivors have neurological sequelae. Japanese Encephalitis spreads by mosquito bite and is maintained by wild and domestic birds and pigs. Humans are dead end host as they don't spread the disease because of brief viremia. JE is generally a disease of the children but affects the adults also in the newly invaded areas. JE occurs in two distinct patterns, in the northern regions as summer epidemics and in southern regions as sporadic or endemic disease. Occurrence of JE has been linked to rainfall and high temperature when mosquito density increases. In north India, JE occurs in the months of August to October. The areas of occurrence of JE have been increasing because of pig farming, paddy cultivation, poverty and poor sanitation. JE has been controlled in Japan, Korea and Taiwan because of vaccination, improvement in socioeconomic status and improved agricultural practice and pig farming. In North India, JE vaccination program has been initiated now.