DYNAMIC PATHOLOGY AND PATHOGEN DISTRIBUTION STUDY ON YELLOW CATFISH PELTEOBAGRUS FULVIDRACO INFECTED WITH EDWARDSIELLA ICTALURI

Using pathologic and immunohistochemical method, we studied the dynamic pathology and pathogen distribution of yellow catfish(Pelteobagrus fulvidraco) that infected with Edwardsiella ictaluri by intraperitoneal injection. Syndromes of infected fish included slowed / twisted swimming, external / internal bleeding / swollen, yellowish / bloody ascites in the abdominal cavity, etc. Histopathologically, after 8—12h of infection, vacuolar degeneration and interstitial nephritis were observed in liver and the kidney; after 24h, focal necrosis appeared in liver, renal tubular epithelial cells degeneration and more severe interstitial nephritis were founded in kidney, followed by hemorrhages on spleen and lymphocyte necrosis; after 48h, liver, spleen, and kidney showed more serious necrosis, causing death of infected fish. E. ictaluri could be detected positive in the liver in 8h of infection, and in the liver, kidney and spleen in 12h, and extended into heart, brain, gills and gut in 48h. It revealed that the pathogen invaded the liver, kidney, spleen first, and then the heart, brain, gills and gastrointestinal tract.