长吻鮠幼鱼小瓜虫病的组织学观察

Histological Observation of Juvenile Leiocassis Longirostris Infected by Ichthyophthirius Multifiliis

多子小瓜虫 (Ichthyophthiriusmultifiliis)主要寄生于鱼类皮肤、鳍、颌须、颏须和鳃 ,在长吻幼鱼的肌肉组织边缘发现有多子小瓜虫幼虫寄生 .感染部位均有上皮和结缔组织增生 ,形成白色囊泡 .皮肤和触须上的一些寄生部位糜烂、充血、色素层部分缺失 ,鳍条被挤压变形 ,严重感染者鳍、颌须和颏颏有不同程度的缺失 .讨论了该病造成长吻幼鱼致死率高和难治疗的原因以及可能的防治措施 .

Ichthyophthirius multifiliis Fouquet usually infected the skin, gills, fins and barbels of the juvenile Leiocassis longirostris Günther,and it's theronts were occasionally found in the tissues next to the muscles. The parasite caused hyperplasia of the host epidermis and connective tissues, and surrounded by the hyperplastic tissues. When the mature parasite broke walls consisting of the hyperplastic tissues, it resulted in lesions of the parasitic sites and secondary infection of bacteria. Therefore, some infected sites were usually congestive and ulcerated, and the pigment layer were partly disappeared. Infected barbels were ulcerated and sometimes gradually disappeared. Infected fins were ulcerated and their rays were extruded by the trophonts of the parasite. On the basis of histological observation of juvenile Leiocassis longirostris infected by the parasitic ciliate, it is discussed that I. multifiliis caused high mortality rate of the infected larvae, the reason why it is difficult to treat and the possible treatment measures.