Question
Japanese B encephalitis
Answer
Japanese Encephalitis (JE) is a mosquito-borne viral encephalitis caused by Japanese Encephalitis virus, a Flavivirus, and the leading cause of viral encephalitis in many parts of Asia, including India.
Transmission: transmitted by Culex mosquitoes (C. tritaeniorhynchus), breeding in flooded rice paddies; pigs serve as the amplifying host and wading birds as the reservoir; humans are an incidental, dead-end host.
Clinical features: most infections asymptomatic/mild; a small proportion progress to encephalitis — high fever, headache, altered sensorium, seizures (particularly in children), and a characteristic parkinsonian-like movement disorder in some survivors; significant case-fatality rate and long-term neurological sequelae in survivors.
Laboratory diagnosis: IgM ELISA (MAC-ELISA) on CSF or serum — the mainstay; RT-PCR — most useful very early in illness.
Prevention: JE vaccination (live attenuated SA 14-14-2 strain, or inactivated vaccines); vector control targeting Culex breeding sites; personal protective measures.
Treatment: no specific antiviral therapy; management is entirely supportive.