Background: Japanese encephalitis (JE) is a major public health problem in India. When the first case was reported in 1955, the disease was restricted to south India. The disease spread to north India in 1978 from where extensive and recurrent outbreaks of JE have been reported ever since. An attempt has been made to review the epidemiology of JE over the past 30 years and suggestions made for its prevention and control.
Methods: An epidemiological profile of JE (1978-2009) has been compiled and analysed to understand the trend and status of the disease.
Results: In India, while 24 states are endemic for JE, Uttar Pradesh contributed more than 75% of cases during the recent past. Over the years, the seasonal trend has changed and the epidemic peak of the disease has advanced by one month.
Conclusion: JE is closely associated with the pattern of precipitation, flooding and rice production systems. Analysis of trends and influencing factors will help in designing suitable strategies for the prevention and control of JE in the country. Continuous monitoring of vector populations and JE virus infection rates in vector mosquitoes will help in predicting an outbreak and in taking effective intervention measures.