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Background Japanese encephalitis (JE) is the leading cause of viral encephalitis with high mortality and morbidity in Asia. In Japan, however, the active recommendation of JE vaccine was retracted in 2005 because of the potential risk of acute disseminated encephalomyelitis. We aimed to determine the recent incidence of childhood-onset JE after the domestic change of vaccination policy in Japan, and to analyze the clinical features of affected children. Methods A retrospective nationwide survey was conducted for pediatric patients with JE in Japan from 1995 to 2015. The national surveillance system was used to identify the pediatric patients with JE. Follow-up questionnaires were sent to analyze their clinical and neuroimaging profiles. Results Among a total of 109 patients registered to the national surveillance, 10 (9%) were less than age 15 years. The annual incidence rate of childhood-onset JE was higher during 2005–15 than that during 1995–2004 (4.3 × 10–3 vs 1.1 × 10–3 per 100000, respectively; P =.04). Endemic regions overlapped with prefectures that farmed pigs harboring antibodies against JE virus with high prevalence. Detailed clinical data were collected from 9 patients. None of them died, but 5 of 9 patients (56%) had neurological sequelae after recovery. One patient who was partially vaccinated with 2 doses of JE vaccine fully recovered from a coma. The age of 3 years or less was associated with unfavorable neurological prognosis. Conclusions Our data provide evidence for the importance and prophylactic effect of the JE vaccine in young children in the endemic area. [ABSTRACT FROM AUTHOR]

In 1984, the authors first conducted a nationwide survey of deaf children with a history of maternal rubella (HMR) in special schools for the deaf in Japan. The survey showed that the incidence of congenital rubella syndrome in the Japanese mainlands was similar to those in the United States and Europe. In 1993, a second nationwide survey by the authors evaluated the efficacy of the vaccination program for schoolgirls begun in 1977. This second survey yielded 272 deaf children with HMR born between 1981 and 1989. Per 100,000 annual livebirths, the incidence rates were 1.56–9.95 in the epidemic years 1981–1982 and 1987–1988 and 0.20–0.72 in the interepidemic years. During the 1987–1988 epidemic, the incidence rates per 100,000 livebirths were 1.52 among mothers eligible for the vaccination program and 5.52–7.44 among mothers not eligible, and the difference was significant. However, only 21.7% of the women who delivered children during the 1987–1988 rubella epidemic were eligible for the vaccination program, and because the majority of deaf children with HMR were born to mothers not eligible, a decrease in the birth rate of deaf children with HMR was not observed. These data suggested the need to introduce a new vaccine program to suppress rubella epidemics. Am J Epidemiol 1998;148:263–8. [ABSTRACT FROM AUTHOR]

Background: Japanese encephalitis (JE) is the leading cause of viral encephalitis with high mortality and morbidity in Asia. In Japan, however, the active recommendation of JE vaccine was retracted in 2005 because of the potential risk of acute disseminated encephalomyelitis. We aimed to determine the recent incidence of childhood-onset JE after the domestic change of vaccination policy in Japan, and to analyze the clinical features of affected children., Methods: A retrospective nationwide survey was conducted for pediatric patients with JE in Japan from 1995 to 2015. The national surveillance system was used to identify the pediatric patients with JE. Follow-up questionnaires were sent to analyze their clinical and neuroimaging profiles., Results: Among a total of 109 patients registered to the national surveillance, 10 (9%) were less than age 15 years. The annual incidence rate of childhood-onset JE was higher during 2005-15 than that during 1995-2004 (4.3 × 10-3 vs 1.1 × 10-3 per 100000, respectively; P = .04). Endemic regions overlapped with prefectures that farmed pigs harboring antibodies against JE virus with high prevalence. Detailed clinical data were collected from 9 patients. None of them died, but 5 of 9 patients (56%) had neurological sequelae after recovery. One patient who was partially vaccinated with 2 doses of JE vaccine fully recovered from a coma. The age of 3 years or less was associated with unfavorable neurological prognosis., Conclusions: Our data provide evidence for the importance and prophylactic effect of the JE vaccine in young children in the endemic area., (© The Author(s) 2018. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)