Yersiniosis in Atlantic cod, Gadus morhua (L.), characterization of the infective strain and host reactions. Issue 6 (21st June 2013)

• Record Type: Journal Article
• Authors: Gudmundsdottir, B K; Gudmundsdottir, S; Gudmundsdottir, S; Magnadottir, B
• Is Part Of: Journal of fish diseases. Volume 37:Issue 6(2014:Jun.)
• Page Start: 511
• Page End: 519
• Publication Date: 2013-06-21
• Subjects: Fishes -- Diseases -- Periodicals; 639.3
• DOI: 10.1111/jfd.12139
• Languages: English
• ISSNs: 0140-7775

Abstract

<abstract abstract-type="main" id="jfd12139-abs-0001"> <title>Abstract</title> <p>A disease outbreak in farmed Atlantic cod caused by <italic>Yersinia ruckeri</italic> is reported. Mortality started following vaccination of cod reared in two tanks (A and B). The accumulated mortality reached 1.9% in A and 4.8% in B in the following 30 days when treatment with oxytetracycline was applied. Biochemical and molecular analysis of <italic>Y. ruckeri</italic> isolates from the cod and other fish species from fresh and marine waters in Iceland revealed a high salinity‐tolerant subgroup of <italic>Y. ruckeri</italic> serotype O1. Infected fish showed clinical signs comparable with those of <italic>Y. ruckeri ‐</italic>infected salmonids, with the exception of granuloma formations in infected cod tissues, which is a known response of cod to bacterial infections. Immunohistological examination showed <italic>Y. ruckeri</italic> antigens in the core of granulomas and the involvement of immune parameters that indicates a strong association between complement and lysozyme killing of bacteria. Experimental infection of cod with a cod isolate induced disease, and the calculated LD<sub>50</sub> was 1.7 × 10<sup>4</sup> CFU per fish. The results suggest that yersiniosis can be spread between populations of freshwater and marine fish. Treatment of infected cod with antibiotic did not eliminate the infection, which can be explained by the immune response of cod producing prolonged granulomatous infection.</p> </abstract>