Moritella viscosa Ulcers of indeterminate cause have been appearing on the

Moritella viscosa ulcers of indeterminate cause have

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Moritella viscosa Ulcers, of indeterminate cause, have been appearing on the flanks of Atlantic salmon in seawater during winter (= winter ulcer disease), principally in Iceland and Norway (Salte et al, 1994; Lunder et al, 1995; Benediktsdottir et al, 1998), and more recently in Scotland. Since its first recognition, a view has emerged that two new vibrios, V. wodanis and Moritella viscosa, are responsible (Benediktsdottir et ai, 2000). Moritella viscosa was subsequently recovered from two diseased (with skin lesions) farmed Atlantic cod in Norway (Colquhoun et ai, 2004). Moraxellaceae representatives Acinetobacter sp. During Autumn 1978 when the water temperature was between 8 and ITC, an outbreak of disease occurred in a group of 60 sexually mature Atlantic salmon. The fish, each of 5-12 kg in weight, were wild stock from the River Surma, Norway,
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36 Bacterial Fish Pathogens and were held in brackish water during the occurrence of disease. During the 5-week period of disease, the cumulative mortahties amounted to 92% of the population. However, only about 40% of the animals displayed clinical signs of disease, namely hyperaemia of the dermal blood vessels, and haemorrhaging in the scale packets, with severe oedema extending into the lower epidermis in the vicinity of the base of the fins. Ulceration developed. Lesions appeared in the kidney, liver and spleen, and small haemorrhages occurred in the air bladder and on the visceral peritoneal sur- faces (Roald and Hastein, 1980). Moraxella sp. During winter 1987, mortalities were recorded among juvenile striped bass, Morone saxatilis, in the Potomac River, Maryland. Gills of diseased fish were affected with the parasites Trichodina and Ergasilus. In addition, a reo-like virus and a bacterium were recovered from some individuals. Large haemorrhagic lesions and missing scales occurred on the dorsal surface of the 11 affected fish. Haemorrhages were apparent in the swim bladder. The liver was enlarged, pale and mottled in appearance. Mem- branous material appeared to connect the liver with the body wall (Baya et ai, 1990b). Mycoplasmataceae representative Mycoplasma mobile The mycoplasma was associated with "red disease", a condition in the gills of tench (Tinea tinea) (Kirchhoff e^ al., 1987). Neisseriaceae representative Aquaspirillum sp. There has been a report of putative Aquaspirilllum sp., along with Aer. hydrophila, Pseudomonas sp. and Streptoeoeeus sp., being associated with a disease, termed epizootic ulcerative syndrome, in snakeheads and catfish obtained from two fish farms in Thailand (Lio-Po et ai, 1998). However, the evidence for the involvement of Aquaspirillum is not convincing. Oxalobacteraceae representative Janthinobacterium lividum During 1991, purple-pigmented. Gram-negative rod-shaped bacteria were associated with mortalities at two fish farms. At one site in Scotland, moribund rainbow trout (size range = 0.5-1.0 g) were diagnosed with RTFS. The second site in Northern Ireland also experienced high mortahties (~35% of the stock) in rainbow trout fry of 0.2-0.5 g in size, two to three weeks after the introduction of feeding. At this site, the rise in mortalities coincided with a change from the use of spring to river water
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