A Survey of the Clinical Sequelae of Japanese Encephalitis
1996 Vol.12 NO.2
Japanese encephalitis (JE) is a major public health issue. In some areas of Asia － for instance, Thailand, Myanmar, Vietnam, India and Indonesia － the disease is most prevalent and causes serious sequelae in both children and adults(1). The disease was made reportable in Taiwan in 1955 and, to date, some 10 confirmed cases have been reported each year (6). The age of JE patients here seems to have increased in recent years. To better understand the new distribution of cases and their sequelae, a survey was conducted.
JE virus is a kind of RNA virus of the flaviviridae group (1). Though the process is difficult, the virus can still be cultured by using either the kidney cell strain of monkey or the chicken embryo cell. The host and reservoir are either pigs or birds, with the mosquitoes, most commonly Culex tritaeniorhynchus, the main vector of transmission. The natural cycle of the virus is this: in late spring and early summer, the virus breeds in either birds or pigs, moves on to mosquitoes whose bite transfers it to other birds and pigs to increase the magnitude of infection. The number of infected mosquitoes reaches peak in mid-summer, and the infection of man then begins. The incubation period is from one to two weeks. In acute onset, patients will have headache for one to three days with occasional nausea or significant loss of body weight. Some 85 to 90% of the JE victims will have high fever and even serious onset of stupor, lethargy or epilepsy. In many children, meningeal symptoms such as stifflness, and even opithotonus, of the neck may develop. Occasionally, some cerebro-nervous and kinetic-nervous symptoms such as facioplegia, clenching of teeth, diplopia, strabismus, nystagmus, dyscatabrosis and dysphagia may occur; some pyramidal and extrapymidal symptoms such as stiffness or slow movement of the limbs, atrophy and choreoathetosis may also develop (1.8).