侵入后先在局部神经末梢或在附近肌细胞中增殖后再侵入神经末梢，沿周围传入神经轴索上行至脊髓前背根神经大量增殖，然后侵入脊髓和中枢神经系统，主要侵犯脑干、基底节、海马回及小脑等处神经元，引起弥漫性脑脊髓病变；再沿传出神经侵入各组织器官继续复制。
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