Histopathological examination revealed the hemorrhagic and necrotic inflammation of the liver at 24h post inoculation. At 48h to 96h post inoculation, proliferative inflammation was observed. 感染雏鸭的组织病理学变化结果显示:感染雏鸭的肝组织在接种后24h表现出血性坏死性肝炎,接种后48-96小时呈增生性病变;