Disease mechanisms of emaciation disease of tiger puffer

1)本文对东北虎河豚肠道粘孢子虫进行了寄生虫学检查，并对东方粘孢子虫的形态特征和发育过程进行了研究。sp.，河豚细鞘藻sp.和Myxidium sp. TP. 2）组织病理学检查表明，重度感染Myxidium sp. TP和Leptotheca fugu后，虎河豚肠上皮细胞发生脱落和变性，而感染M.河豚对肠道组织无明显损伤。河豚通过摄食感染组织、与感染鱼同居以及接触养殖池的污水等途径传播。4）研究了Myxidium sp. TP在实验感染鱼体内的动力学。寄生虫的发育被发现是温度依赖性的：它们在20 ℃和25 ℃下发育，而它们在15 ℃下变得“神秘”。实验感染Myxidium sp.TP的鱼在20 ℃下从第3周开始出现水肿，在20 ℃下从第6周开始出现典型的水肿症状。5）感染鱼的吸湿能力显著低于未感染鱼，表明患病鱼的渗透调节功能受到了阻碍。肝脏萎缩，LDH、GOT、GPT等肝脏指标降低，提示肝脏功能紊乱。6）东方鲀消瘦病的病原体为肠道粘孢子虫、粘孢子虫和东方纤鞘虫。传播模式和发育动力学的寄生虫进行了表征。粘孢子虫的严重感染引起肠道渗透调节的显著紊乱，导致消瘦病。

1) Parasitological examinations of myxosporeans from the intestine of emaciated tiger puffer were conducted, and morphological characteristics and developmental processes of Myxidium fugu n. sp., Leptotheca fugu n. sp. and Myxidium sp. TP were described. Further, diagnostic procedures of the above myxosporeans were established based on Diff-Quik-stained intestine imprints and HE ＆ Uvitex2B-stained histological sections.2) Histopathological examinations indicated that heavy infections with Myxidium sp. TP or Leptotheca fugu caused exfoliation and degeneration of the intestinal epithelia of tiger puffer, while M. fugu caused no significant damage in the intestinal tissues.3) Myxidium sp. TP and M. fugu transmitted from fish to other fish by feeding the infected tissues, cohabitation with infected fish and exposure to effluent from a tank holding infected fish.4) Kinetics of Myxidium sp. TP were investigated in experimentally infected fish. Development of the parasites was found to be temperature-dependent : They developed at 20C and 25C, while they became "cryptic" at 15C. Experimentally infected fish with Myxidium sp. TP became anorexic from week 3 at 20C, and showed the typical sign of the from week 6 at 20C.5) Moisture absorbance ability of infected fish was significantly lower than that of uninfected fish, indicating that functions of osmotic regulation were hampered in diseased fish. Further, atrophy of the liver and reduced hepatic indicators (LDH, GOT and GPT) of infected fish suggested that emaciated fish had a functional disorder in the liver.6) The causative organisms of emaciation disease of tiger puffer were demonstrated to be the Intestinal myxosporeans, Myxidium sp. TP and Leptotheca fugu. Modes of transmission and developmental kinetics of the parasites were characterized. Heavy infections with the myxosporeans caused a significant disorder in osmotic regulations in the intestine, resulting in the emaciation disease.