الفهرس 
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Abstract
The present study was carried out on 160 catfish (Clarias lazera ) collected from various fish markets at Egypt , during a period from January 1994 to August 1995 . Out of these fish 150 catfish showed different external lesions .
The results of bacteriological examination identified different bacterial infections with a percentage of 64 % . Various bacterial species including Aeromonas sp.( 46 % ), Pseudomonas sp. ( 6 % ), Flexi-bacter sp. (6.67%) , Edwardsiella sp. ( 4. 67 %) , Corynebacterium sp.( 2.67 % ) Staphylococcus sp. (12 %) , Streptococcus sp. ( 5. 33 % ), Proteus sp. ( 2 %) and Citrobacter sp. ( 1.33 % ) were isolated from these examined catfish . Moreover different parasitic affections ( with an incidence of 84 % ) including encysted metacercarial infections (76. 67%) , parasitic gill infestation ( 16 0:6 ) , intestinal parasitism ( 19 % ) and rnyxosporidian: infection ( 0.67 %) were also recorded .
PATI-1010QiCA1 GRANGES iN CATFISh SUFFEREd from diFFERENT AFFECTIONS
Bacterial affections 2-
i Aeromonas species infections :
The gross examination of catfish infected with Aeromonas species showed unilateral exophthalmia, abdominal distention , fins and gills erosions with cutaneous ulcerations and inflammation of the anal opening . Grossly , congestion of most internal organs , distention of gall bladder with presence of haemorrhagic and necrotic areas on the hepatic and gill surfaces were observed . Microscopically, degenerative changes and necrosis of the hepatocytes myocardium and skeletal muscles with proliferation of renal haemopoeitic tissues were detected . Focal areas of haemorrhages and mononuclear leucocytic cellular infiltration of gills . liver intestinal layers , heart and skeletal muscles were seen . Dermal melanosis . desquamation of the lining epithelium of gills , intestine and epidermis with proliferation of the gill mucous cells and intestinal .Yoblet cells were observed Thrombosis of portal , renal and splenic blood vessels with depletion of lymphoid tissues and proliferation of inelanomacrophage centers and reticuloendothelial tissues in the spleen were detected .
’Pseptaoknonas species infections
Externally , bilateral exophthalmia with eroded body fins
and ulceration of the skin were observed in cases of Pseudomonas species infection Grossly enteritis , palness of liver and kidney . congestion of gills and heart with necrosis of the underlying muscles of the skin were seen. Microscopically, similar changes observed in cases of Aeromonas infection were observed in catfish infected with Pseudo-monas species In addition hypertrophy of gill lamellar epithelium with haemosiderosis and focal hyperplasia of lymphoid elements in the spleen were detected . Pericardial edema mononuclear leucocvtic cellular infiltration of necrotic skeletal muscles and hyaline droplet degeneration of renal epithelium with presence of hyaline casts in the lumen of renal tubules were also found . ’Fiexihacter species infections :-
The tail and dorsal fins of catfish infected with Flexibacter species were mostly frayed and eroded . Excess mucous on the gill pouch and body surface with the presence of shallow cutaneous erosions were noticed Congestion of visceral blood vessels , spleen , kidney and gills with destruction and fusion of the free ends of gill filaments were grossly seen . Microscopical examination revealed haemorrhages , degeneration and necrosis in liver , gills , heart , kidneys and skeletal muscles . Proliferation of gill mucous cells, intestinal goblet cells epidermal alarm substance and mucous cells with desquamation of intestinal and lamellar epithelium were found . Splenic haemosiderosis and depletion with activation of melanomacrophage centers in the liver , spleen and kidney were detected . Moreover, mononuclear inflammatory cellular infiltration of the gill arch and pericardium was also noticed .
Eowarosietia species infections :-
[’he external examination of catfish infected with Edwardsiella sp. showed frayed tail fins with the presence of white and reddish raised areas between two eyes . Grossly enteritis with congestion of spleen and paleness of heart , kidney and gills were detected . Microscopically . catarrhal enteritis , suppurative inflammation of gill filaments with congestion and mononuclear leucocvtic cellular infiltration of hepatoportal area, gill arch and myocardium were found . Degeneration. necrosis and haemosiderosis with focal macrophage cellular aggregation in-between the renal tubules in addition to activation of melano-macrophage centers were seen in the kidney . Degeneration of cardiac muscles and hepatocytes with focal heterophilic cellular aggregation in the liver and focal areas of haemorrhage in gills and in-between necrotic skeletal muscles were also recorded .
’Corynehacteriuni species infections :-
The infected catfish with Corynebacterium species showed bilateral exophthalmia with corneal :haemorrhages and superficial skin erosions . Grossly palness of gills , heart and kidney with presence of necrotic areas on the hepatic and renal surfaces were detected . ”l’he microscopical examination of Corynebacterium infection was characterized by presence of multiple abscesses in the renal parenchyma with proliferation of renal melanomacrophage centers and haemopoietic tissues . Renal haemosiderosis with hyperplasia of the lining epithelium of archinephric duct and periductal fibrosis were noticed . Hepatic and splenic necrosis with proliferation of splenic melanomacrophage centers and reticuloendothelial tissues and heterophilic cellular infiltration of hepatic parenchyma were detected . In addition melanomacrophage cellular infiltration of heart , dermis and underlying skeletal muscles was also noticed .
Parasitic affections t-
*Encysteo nietacercarial infections :
The external examination of catfish infected with encvsted metacercaria was characterized by presence of black spots on the caudal portion of the body in addition to skin ulcerations and haemorrhages in some complicated cases . Grossly black and grayish white sand-like masses were observed on the surface of the internal organs . fat tissues and skeletal muscles . The microscopical examination revealed presence of numerous live , dead and calcified cysts with pericystic fibrosis. haemosiderosis . melanosis and mononuclear cellular aggregations . kizenerative changes in the liver and kidney with activation of the renal melanomacrophage centers and haemopoietic tissues were detected . Focal areas of hemorrhages and edema in-between necrotic skeletal muscles were also observed .
’Gitt ectoparasitic infestations :
Grossly infested gills with ectoparasites were mostly inflamed and covered with excessive mucous while their free ends were destroyed . Microscopically cross section of parasites congestion , edema . haemorrhages and focal mononuclear cellular infiltration with hvperplasia of the lamellar epithelium and fusion of the secondary
lamellae were observed .
*Intestinal parasitism :
Grossly, intestine was inflamed and the intestinal lumen was filled with yellowish semisolid content . Microscopically , catarrhal enteritis with presence of cross section of parasites within the intestinal lumen
were detected .
my cosporThian cyst infection :
Grossly the kidney was congested . Microscopically , numerous oval mvxosporidian cysts filled with large number of PAS positive spores and surrounded with a thin layer of connective tissue in-between the renal tubules were detected . Activation of renal haemopi&itic tissues . shrinkage of glomeruli and degeneration of tubular epithelium with the presence of cellular and hyaline casts in the lumen of renal tubules were also observed . from the clinicopathological studies it was evidenced that , high levels of serum AST and ALT with hypoproteinaemia hypoalbumin-aemia and hypoglobulinaemia in addition to elevations of serum creatinine , urea and uric acid values were the main biochemical changes in the serum of catfish suffered from bacterial infections particularly in cases of Pseudomonas and Corynebacterial infections . Moreover . hypocholesterolaemia was recorded in most cases of bacterial infections except in cases of Corynebacterial infections where elevated serum level of cholesterol was recorded .
Parasitic affections :-
The biochemical analysis of the serum of catfish suffered from parasitic affections revealed elevations of creatinine , urea and uric acid values . Low levels of total protein , albumin and globulin were also noticed especially in complicated cases of encvsted metacercarial infections with intestinal parasitism Meanwhile . increases in the serum activities of AST and ALT were recorded only in cases of encysted metacercarial infections . Experimental Aeromonas ybropbitet infection :-
Nearly similar pathological and serum biochemical changes observed in the natural cases of Aeromonas infections were also detected among experimentally inoculated catfish with Aeromonas Irvdrophila
Finally , from the present study we concluded that ;
•Mixed infections with more than one fish pathogens were predominant than infections with only single fish pathogen .
•The percentages of parasitic infections among examined catfish were higher reaching 84 c,’/O and the encysted metacercarial infection was higher one ( 76.67 % ) . Meanwhile , the percentage of bacterial infection reaching 64 % and Aeromonas species infection was the higher one among examined catfish ( 46 %) .
•The pathological changes in both Aeromonas and Pseudomonas species infections were nearly similar and had no specific lesions while Flexibacter species infection was characterized by gill and skin lesions and Corynebacterium species infection was characterized by renal lesions .
The clinicopathological studies revealed that , serum biochemical changes in bacterial and / or parasitic infection were reflected the severity of pathological damages but were not specific .
•Some microorganisms as Staphylococcus and Streptococcus or intestinal parasites had a little pathogenic effects but they may play an important role in lowering of fish resistance .
•The high percentage of encysted metacercarial infection may reflected the high environmental pollution among human being , birds , dogs and cats.