Japanese Encephalitis Virus Strain SA 14-14-2 Antigen (Formaldehyde Inactivated): A Comprehensive Review

1. Introduction to Japanese Encephalitis Virus Strain SA 14-14-2 Antigen (formaldehyde inactivated)

Overview of Japanese Encephalitis (JE) and Its Public Health Significance

Japanese Encephalitis (JE) is a severe mosquito-borne viral illness and a leading cause of viral encephalitis in Asia, particularly Southeast Asia.[1] The disease is caused by the Japanese Encephalitis Virus (JEV), a member of the Flaviviridae family.[3] JEV transmission follows a zoonotic cycle involving mosquitoes (primarily Culex species) as vectors, with water birds serving as natural reservoirs and pigs acting as significant amplifying hosts.[3] Humans are generally considered incidental or dead-end hosts because the level of viremia in infected individuals is typically insufficient to infect mosquitoes.[3]

While a large proportion of JEV infections are subclinical or result in mild, undifferentiated febrile illness, the development of clinical JE can have devastating consequences.[3] The incubation period in humans is estimated to be 5 to 15 days, often followed by the sudden onset of fever.[3] If the virus invades the central nervous system, it can manifest as meningitis, encephalitis, or myelitis.[3] Children are particularly vulnerable, often presenting with altered sensorium, seizures, and other severe neurological symptoms.[3] Approximately 1 in 250 JEV infections results in clinical disease.[3] Among those who develop encephalitis, the case-fatality rate can be as high as 30%, and around 30-50% of survivors experience significant long-term neurological or psychiatric sequelae, leading to lifelong disability.[3]