Wu YC, Huang YS, Chien LJ, Lin TL, Yueh YY, Tseng WL, Chang KJ, Wang GR
           National Institute of Preventive Medicine, Department of Health, Taipei,
           Taiwan, Republic of China.
           Am J Trop Med Hyg 1999 Jul;61(1):78-84

        Japanese encephalitis (JE) is an endemic disease in Taiwan. A mass
        vaccination program of children against JE was first implemented in
        1968. Along with general improvements in various aspects of living
        conditions over the years, the program has brought JE well under
        control. The main characteristics of JE epidemiology in Taiwan in the
        past 3 decades are as follows. The transmission mode remains
        unchanged-that is, the amplification stage of the virus in pigs is
        followed by a human epidemic each year. The frequency of JE incidence
        has dropped significantly. The incidence rate of confirmed cases was
        2.05 per 100,000 in 1967, the highest in record, and merely 0.03 per
        100,000 in 1997. Confirmed cases occur sporadically all over the island.
        The peak of the epidemic season has shifted from August in the 1960s to
        June since the 1980s. The age distribution of confirmed cases has
        shifted gradually from mainly children to adults. Vaccine efficacy for
        those having received more than 2 doses of the vaccine is estimated to
        be about 85%.