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Cold Water Vibriosis
Introduction/Aetiology
Vibrio salmonicida, the agent of Hitra disease, a cold water vibriosis affecting Atlantic salmon (Salmo salar), is a facultatively anaerobic motile rod. This disease affects mainly fish farms with Atlantic salmon and occasionally with rainbow trout. Vibrio salmonicida has also been described as the aetiological agent of cold-water vibriosis affecting cod in Norway (Sorum et al., 1990). Hitra disease occurs mainly in late autumn, winter or early spring.
Epidemiology
Hitra disease appeared in 1977 and occurred for the first time on a large scale in 1979 in fish farms in the Norwegian island of Hitra. Since then, it has devastated fish farms located along the western and northern Norwegian coast (Egidius et al., 1981). However, single outbreaks have also been reported in Scotland (Bruno et al., 1985, 1986), on the Faroe Islands (Dalsgaard et al., 1988) and in New Brunswick and Nova Scotia, Canada (reference in Sorum et al., 1992).
Epidemiological studies based on plasmid profiles suggest that V. salmonicida was transmitted from cod to Atlantic salmon and vice versa in fish farms in northern Norway (Sorum et al., 1990).
Diagnosis
The characteristics of this disease, also known as haemorrhagic syndrome, are anaemia and haemorrhages with a generalized septicaemia, presenting large amounts of bacterial cells in the blood of moribund or recently dead fish. The haemorrhages are mainly found in the integument surrounding the internal organs of the fish ( Poppe et al., : Egidius et al.,)
Treatment
References
© CAB INTERNATIONAL 1999. Fish Diseases and Disorders, Volume 3: Viral, Bacterial and Fungal Infections (eds P.T.K. Woo and D.W. Bruno)
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