Japanese Encephalitis Virus Poses Significant Threat in Asia

Japanese Encephalitis Virus (JEV), a mosquito-borne flavivirus, poses a significant public health threat across Asia, causing an estimated 100,000 clinical cases each year. The World Health Organization (WHO) reports that the case-fatality rate among symptomatic patients can reach as high as 30%, with 30-50% of survivors experiencing permanent neurological, cognitive, or behavioral impairments.

The virus is transmitted to humans primarily through the bite of infected Culex mosquitoes, particularly Culex tritaeniorhynchus. The virus cycles between mosquitoes, pigs, and/or water birds before infecting humans. JEV is most prevalent in rural and semi-urban areas where human populations are in closer proximity to these animal reservoirs. In temperate regions of Asia, transmission is seasonal, peaking during warmer months, while in tropical and subtropical areas, transmission can occur year-round, often intensifying during the rainy season.

While most JEV infections are asymptomatic or result in mild symptoms like fever and headache, approximately 1 in 250 infections progresses to severe encephalitis. Symptoms of severe disease include a sudden onset of high fever, severe headache, neck stiffness, disorientation, coma, and seizures. There is no specific antiviral treatment for JE; care focuses on supportive measures to manage symptoms and aid recovery.

WHO recommends that JE vaccination be integrated into national immunization programs in endemic regions. Despite the availability of safe and effective vaccines, over 3 billion people in the WHO South-East Asia and Western Pacific Regions are at risk of JEV transmission. Diagnosis typically involves clinical assessment followed by laboratory confirmation of JEV-specific IgM antibodies.