28th ANNUAL EASTERN FISH HEALTH WORKSHOP April 21-25, 2003 Histological And Ultrastructural Lesions Associated With Chronic Diarrhea In Arctic Char Alicia C. Noble1, Michael M. Garner2, and Robert W. Nordhausen3 1Freshwater Institute, P.O. Box 1889, Shepherdstown, WV 25443; 2Northwest ZooPath, 18210 Waverly Drive, Snohomish, WA 98296-4815; 3California Animal Health and Food Safety Laboratory, School of Veterinary Medicine, University of California, Davis, CA 95616. Arctic char (Salvelinus alpinus) cultured in a recycle growout system at the Freshwater Institute were diagnosed with chronic diarrhea.  The number of fish affected was estimated at over 50% and ranged from 800 grams to 1.6 kilo.  Histology revealed severe granulomatous gastritis with mineralization occurring within granulomas and in the collagen of the submucosa and smooth muscle of the muscular tunic.  Present also was mild to moderate proliferative colitis, hepatic lipidosis, and mild non-suppurative serositis.  Electron microscopy of the stomach revealed that cytoplasmic structures in the macrophages and multinucleate cells, interpreted by light microscopy as possible infectious agents, represented phagolysozomes, some with central mineralization or compact membranous swirls.  These were interpreted as the early stages of the mineralization process.  The most recent sample taken had histological changes that were consistent with ongoing inflammation throughout the intestinal tract.  Severe chronic/active transmural enteritis and severe granulomatous gastritis with mineralization were observed. Electron microscopy of the intestine is pending.  Differential diagnoses and possible mechanisms to explain these findings will be discussed. Return to 28th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page