Location: Warmwater Aquaculture Research UnitTitle: The pathology associated with visceral toxicosis of catfish) Author
Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/10/2011
Publication Date: 11/15/2011
Publication URL: http://handle.nal.usda.gov/10113/55578
Citation: Khoo, L.H., Goodwin, A.E., Wise, D.J., Holmes, W.E., Hanson, L.A., Steadman, J.M., Mcintyre, L.M., Gaunt, P.S. 2011. The pathology associated with visceral toxicosis of catfish. Journal of Veterinary Diagnostic Investigation. 23(6):1217-1221. Interpretive Summary: The clinical signs, gross and histopathologic lesions associated with Visceral Toxicosis of Catfish were described in the manuscript. Correlation of the gross and histopathologic lesions as well as explanations for the abnormal behavior and histopathologic signs were given. However although the gross lesions and clinical signs are very suggestive for the disease, the histopathologic lesions are nonspecific and cannot form the basis of a definitive diagnosis of this syndrome. Confirmation of the intoxication requires a bioassay and specialized tests like the endopep mass spectrometry is required for a definitive diagnosis.
Technical Abstract: Visceral toxicosis of catfish (VTC) syndrome was recognized in the late 1990s and recently has been associated with exposure to Clostridium botulinum type E neurotoxin. Tentative diagnosis is based on clinical presentation and ross findings, and is confirmed by bioassay. In April 2009, channel catfish (Ictalurus punctatus) from 2 different farms presented with abnormal swimming behavior and mortalities. Nine fish were submitted to the Aquatic Research and Diagnostic Laboratory (Stoneville, Mississippi) for evaluation. Bacterial cultures from these fish were negative. Necropsy findings included intestinal intussusceptions, ascites, pale proximal intestines with engorged serosal blood vessels, splenic congestion, and a reticular pattern to the liver. Significant histopathologic findings were limited to cerebral , splenic and hepatic congestion, splenic lymphoid depletion and perivascular edema, vascular dilation and edema of the gastrointestinal tract, and perivascular edema in the anterior and posterior kidneys. Intoxication from C. botulinum type E neurotoxin was suspected based on the clinical signs and lack of gross and microbiological evidence of an infectious disease process. The toxicosis was confirmed with a positive bioassay using serum collected from the submitted fish.