A comparative analysis of Japanese Encephalitis Virus (JEV) in Asia: patterns of transmission, clinical diagnosis, and control strategies

Abstract

Japanese Encephalitis Virus (JEV) is a flavivirus transmitted by mosquitoes and one of the foremost causes of viral encephalitis infection in Asia, predominantly occurring in children in rural areas. Initially isolated in Japan in 1924, JEV is largely spread by Culex mosquitoes, notably Culex tritaeniorhynchus and Culex gelidus, breeding in paddy fields. The virus has a zoonotic cycle with pigs as amplifying hosts and ardeid birds as reservoirs. JEV outbreaks reach their peak during the monsoon months (July–September). Severe encephalitis may occur with manifestations such as fever, vomiting, seizures, paralysis, and coma. The case fatality rate is approximately 30 %, and survivors can have long-term neurological complications. JEV invades the central nervous system by crossing the blood-brain barrier, causing neuroinflammation and neuronal damage. Diagnosis is made with serological tests and molecular tests. JEV is endemic in India, Nepal, China, Myanmar, Vietnam, and other Asian nations. In India, 1000–2500 cases occur each year, with underreporting suspected. Bihar is a focused area, with Muzaffarpur district having a high incidence. Control is based on vaccination and vector control. Four vaccines are available, but limited coverage underscores the necessity for increased immunization and surveillance.