Susceptibility of channel catfish, Ictalurus punctatus (Rafinesque), to Edwardsiella ictaluri challenge following copper sulphate exposure

• Published in: Journal of fish diseases 2007-10, Vol.30 (10), p.581-585
• Main Authors: Griffin, B R, Mitchell, A J
• Format: Article
• Language: English
• Subjects: Animals; copper; Copper Sulfate - analysis; Copper Sulfate - toxicity; copper sulphate; Edwardsiella ictaluri; Edwardsiella ictaluri - pathogenicity; enteric septicaemia of catfish; Enterobacteriaceae Infections - immunology; Enterobacteriaceae Infections - mortality; Enterobacteriaceae Infections - veterinary; Environmental Exposure; fish disease; Fish Diseases - immunology; Fish Diseases - microbiology; Fish Diseases - mortality; Fresh Water - analysis; Freshwater; Ictaluridae; Ictalurus punctatus; Ictalurus puntatus; Immunity, Innate - drug effects; Survival Analysis; Time Factors; Water Pollutants, Chemical - toxicity
• ISSN: 0140-7775; 1365-2761
• DOI: 10.1111/j.1365-2761.2007.00838.x

Channel catfish, Ictalurus punctatus (Rafinesque), with or without a preliminary 24 h exposure to 2 mg copper sulphate L−1, were challenged with 7.5 × 106 colony forming units L−1 of Edwardsiella ictaluri to determine the effect of copper sulphate on disease resistance. Catfish previously exposed to copper sulphate were significantly more resistant to the bacterial challenge than those not exposed. Catfish not exposed to copper sulphate suffered 35.5% mortality while catfish exposed to copper sulphate experienced 14.1% mortality. Copper concentrations were the same in tank waters of both exposed and control fish at the time of challenge, eliminating the possibility that copper in the water may have been toxic to bacteria. Copper concentrations in freeze dried and ground tissues of unexposed, exposed, and purged channel catfish were highest in fish before copper sulphate exposures suggesting that elevated tissue levels of copper were not responsible for the increased resistance to bacterial challenge. Competition for sites of bacterial attachment to gill or epithelial cells may account for the reduction in mortality; although this is not supported by the low copper content of fish tissue after copper exposure.