一、流行情况:1955—1992年38个年份,总共发生乙脑4880例,年发病率最高为99.21/十万(1970),最低0/十万(1988年),其间1957年、1967年、1968年、1970、1975年曾出现过较大流行,非流行年份发病率高低不稳,总趋势呈下降曲线,流行间歇期不明显。发病率与病死率曲线呈相反象,发病率高的年份病死率低,发病率低的年份病死率相 First, the prevalence of: 1955-1992 38 years, a total of 4880 cases of Japanese encephalitis, the annual incidence of up to 99.21 / 100,000 (1970), the lowest 0 / 100,000 (1988), during which 1957, 1967, 1968, 1970, 1975, there have been a larger epidemic, non-epidemic year high and low incidence of instability, the overall trend showed a downward curve, the epidemic interval is not obvious. Morbidity and mortality curves were the opposite, the high incidence of mortality in the years with low morbidity and mortality in the low phase of the year