| Balantidiasis is caused by ciliate, ciliate belongs to the cilia door of protozoasubkingdom, their differentiated degree are the highest in protozoa. Some speciesare directly or indirectly dangerous to the fishes, lead to mass death of fish, and cause agreat loss for the fishery production. Therefore, this thesis researched epidemiology,histopathology and control on several important balantidiasis, provided the theory basis andthe technical support to the effectively control of balantidiasis.The trichodiniasis in Takifugu obscurus occurred all the year round, it was particularlyprevalent from April to August when the water temperature between20℃and28℃. It’sinfection ratio was nearly100%, could caused more than10%of Takifugu obscurus death.The typical symptoms were as follows: surface of sick fish became dull and darken, mucusof body surface and gill filaments secretion increased more in the early stage; sick fishswam along the pool, the severe ones appeared serious skin redness, ulcers, rotten fins andmechanical friction damage; abdominal cavity effusion, liver and intestinal hyperemiathrough anatomy of the diseased fish; the sick fish loss of appetite, dull-witted, breatheddifficultly and eventually died in the later stages.The pathological results showed that large number of epithelial cell in the secondarygill lamellae swelled and fell off; the single cell of surface became hyperplasia,structure rough and color darker; the gill filament became deformation and shortage. Thesurface cells in skin were proliferated, necrotic, and came off. The edema, necrosis anddissolution were found in the liver. The spleen appeared brown patches under HE staining.Large area renal tubular was necrotic and collapsed, or even completely disappeared, renalinterstitial fused. The cardiac muscle fibers were cracked and disintegrated. The intestinalmucosas darken, the muscular layer of intestines wall were congested and nucleus darken.The effect of salinity on Takifugu obscurus and killing Trichodina sp. on its body wereanalyzed. The results showed that Takifugu obscurus could survive safely under salinity15.However, the number of parasite Trichodina didn’t reduce, but was tending to increase in4days if the salinity was low than5.0. Instead, Trichodina could been killed more than95%by maintaining salinity at7.5for4days or10for3.5days,12.5for3days. The parasiteswere been killed entirely if salinity was rose to15for32h,17.5for24h,20.0for10h,25.0for4h,30.0for1.5h,35.0for1h and40.0for0.5h. The fitting curve equation of salinityand killing time for Trichodina was analyzed. Its mathematical model was logarithmiccurve equation of y＝34.19－5.55㏑x. Nevertheless, there was adverse impact on Takifugu obscurus when salinity above15. Histopathological analysis showed that part of gilllamella enlarged and mixed at end; the liver tissue was congested; there were a largeamount of hemosiderosis in the spleen tissues; epithelial cells of renal tubular appearedcoagulation necrosis, glomerulus were necrotic and collapsed; intestinal epithelial cellswere degenerated and fell off, microvilli were not neat and vague, sometimes evendisappeared. Additionally, it was confirmed that the Trichodiniasis of Takifugu obscurusdid not reappear with salinity5.0during farming through the resurgence test of Trichodinasp. on fish body surface. Our conclusion supported that trichodiniasis of Takifugu obscuruscould be cured if maintain salinity high than7.5. Salinity from7.5to15was suggested tobe good choice for treatment of the trichodiniasis in Takifugu obscurus culture.The Cryptocaryon irritans only about30μm drilled into fish gills and skins, derivedits nourishment by absorbing cells and tissues of the host, developed into trophonts, thetrophonts could reach more than500μm in the host. In the process of this development,the parasites havocked on the gill filaments of the host, and caused secondary gill lamellaeexpanded and coarsened, showed club-shaped, the gill filament structure even ruptured ordisappeared. The parasites lived on the skins of fishes; caused epidermal tissues thickenand swelled obviously. Although there were no Cryptocaryon irritans in internal organs，the parasites severely damaged gill filaments and skin tissues, led to the fishes stop feeding,so visceral organs also would appear different pathological changes. The histopathologicanalysis found that: the liver partial necrosed and dissolved, the cell nucleus were solidifiedand darkened; amount of hemoferrin the spleen subsided in the spleen, part of the tissueswere necrosed; renal capsule were closed, renal tubular epithelial cells necrosed anddissolved; part of myocardial were necrotic, and a small amount of inflammatory cellsinfiltrated; there were areas of necrosis and collapse of intestinal epithelial cells.The killing effect of compound Chinese herbal medicine "HD-2" and drug-containingserum on Cryptocaryon irritans showed that: the concentration of50ppm of Chinese herbalmedicine possessed the ability to kill Cryptocaryon irritans, however, the killing effect ofdrug-containing serum was not obvious, it might was because that the concentration ofChinese herbal medicine in the blood was not high, it had no insecticidal action, but couldinhibit the activity of the parasites, so as to expel the parasites. A number of clinicaltreatment trials on aquaculture farms showed that, compound Chinese herbal medicine"HD-2" had the preferable curative effect to cryptocaryoniosis of turbot. The diseasesituation had been effectively controlled10days later, by oral and medicated bath Chineseherbal medicine "HD-2". The turbot fed normally, stopped death and cured thepathogenetic condition after10days, by oral and dipping compound Chinese herbalmedicine combined with formaldehyde are used together. The single using formaldehyde inthe treatment of cryptocaryoniosis could halt the progression of the disease in a short time,but the state of illness would be repeated and aggravated. Chinese herbal medicine combined with formaldehyde to prevent and control cryptocaryoniosis was discussed inthis paper, this was a new idea. Formaldehyde had the advantages of suppressing thedisease in short time, Chinese herbal medicine had important roles in expelling parasite,nursing the health enhanced resistance of fish, the two complemented each other, thiswould provide a new idea for preventing and controlling cryptocaryoniosis ofScophthalmus maximus.The oral compound Chinese herbal medicine "HD-2" test showed it had good controleffect against cryptocaryoniosis of pseudosciaena crocea. The oral "HD-2" prevention triallast for2months, with the dosage of were10g/kg and5g/kg bait, the results showed that theaverage daily deaths of the juvenile pseudosciaena crocea fell of by32.27%and25.45%,the average daily deaths of the adult pseudosciaena crocea fell of by41.35%and36.07%.Finally, base on the above research, the epidemiology of balantidiasis was elucidated,the histopathologic changes of trichodiniasis in Takifugu obscurus and cryptocaryoniosisin Scophthalmus maximus were analyzed, and the comprehensive prevention and controltechnology were established respectively. This technology had succeeded in clinicalexperiment and extension, and helpful in balantidiasis control and healthy management ofcultured fish. |
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