Preventive strategies for frequent outbreaks of Japanese encephalitis in Northern India

Japanese encephalitis (JE) remains the most important cause of acute viral encephalitis and continues to spread to hitherto unaffected regions like Indonesia, Pakistan and Australia. Approximately 60% of the world population inhabits JE endemic areas. Despite its restricted range mostly in the developing countries, a high annual incidence of 50,000 cases and about 10,000 deaths has been reported. Disease can be fatal in 25% cases. Magnitude of the problem is even more alarming since the survivors are left with serious long-term neuropsychiatric sequelae. Almost every two years, epidemics of JE occur in Indian subcontinent with a high mortality. JE virus infection results in different disease manifestations in host from mild subclinical febrile illness to clinical infections leading to encephalitis. No antiviral treatment is so far available for JE. The prevention of JE can be achieved by controlling the vector or by immunization regime. The vector control in the rural areas, which are the worst affected ones, is practically almost impossible. Three vaccines that have been implicated against JE include inactivated mouse brain derived, inactivated cell culture derived and cell culture derived live attenuated JE vaccine. But each has its own limitation. Currently, attempts to synthesize recombinant DNA vaccine are being made. New therapeutics are on the way of development like use of minocycline, short interfering RNA, arctigenin, rosmarinic acid, DNAzymes etc. However, the immune mechanisms that lead to JE are complex and need to be elucidated further for the development of therapeutics as well as safe and efficacious JE vaccines.