Japanese Encephalitis

Japanese encephalitis is the most common preventable cause of mosquito-borne encephalitis in Asia, Australia, and the western Pacific.  The Culex species of mosquitoes transmit the virus with their bite. Transmission occurs most commonly in agricultural areas such as farms and rice paddies but may occur in urban areas under certain conditions. While the vast majority of infections are asymptomatic, those who do develop symptoms of encephalitis suffer significant morbidity and mortality. Symptomatic patients develop a high fever, headache, disorientation, coma, tremors and mental status changes due to cerebral inflammation. Movement disorders, neurologic deficits, and seizures are common, particularly in children. Approximately one in four symptomatic cases are fatal. Children are most commonly affected, and most people who reside in endemic areas will have immunity by adulthood. There is no specific therapy beyond supportive care, but there is an effective vaccine available to prevent infection. The vaccine is recommended for high-risk travelers to endemic areas. Many endemic areas have implemented childhood vaccination programs. The best protection is the prevention of mosquito bites.
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