流行性乙型脑炎 ,简称乙脑 ,又称大脑炎 ,是一种常见传染病。在我国的发病分布具有明显的季节性 ,主要在夏秋季流行 ,南方地区一般在 6月份开始流行 ,北方地区要晚 1个月。我国85%以上病例发生在 7～ 9月。自 2 0世纪 70年代中期 ,我国开始大规模接种乙脑疫苗以来 ,乙脑发病率 Japanese encephalitis, referred to as JE, also known as encephalitis, is a common infectious disease. The distribution of the disease in our country is obviously seasonal, mainly prevailing in summer and autumn. The southern areas generally begin to popularize in June and the northern areas one month later. More than 85% of cases in China occurred from July to September. Since the mid-1970s, when large-scale vaccination of Japanese encephalitis vaccine started in our country, the incidence of Japanese encephalitis