611
et al. 1983 ), and by inference to Halomonas cupida on the basis of 16S rRNA
sequencing (Dobson and Franzmann 1996 ).
Epizootiology
H. cupida is a waterborne organism (Baumann et al. 1972 ). Therefore, the source of
infection was most likely the marine environment.
Pathogenicity
Pathogenicity was confi rmed in laboratory-based experiments involving waterborne
challenge with 10
3 –10
5 cells/ml. Approximately 75 % mortalities were recorded
within 4 days Kusuda et al . ( 1986 ).
Moraxellaceae Representatives
Acinetobacter sp.
Characteristics of the Disease
During Autumn 1978 when the water temperature was between 8 and 11 °C, an
outbreak of disease occurred in a group of 60 sexually mature Atlantic salmon. The
fi sh, each of 5–12 kg in weight, were wild stock from the River Surma, Norway, and
were held in brackish water during the occurrence of disease. During the 5-week
period of disease, the cumulative mortalities 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 fi ns. Ulceration developed. Lesions appeared in the kidney, liver and spleen, and
small haemorrhages occurred in the air bladder and on the visceral peritoneal surfaces (Roald and Hastein 1980 ).
Isolation
Pure cultures were recovered on 5 % (w/v) blood agar supplemented with 0.5 %
(w/v) sodium chloride, following incubation at 22 °C for 48 h. Thus, blood, kidney,
liver, spleen and ulcers in the muscle appeared to contain dense bacterial populations. Pure cultures were obtained, which were capable of reproducing the infection
during laboratory-based studies (Roald and Hastein 1980 ).
Moraxellaceae Representatives
et al. 1983 ), and by inference to Halomonas cupida on the basis of 16S rRNA
sequencing (Dobson and Franzmann 1996 ).
Epizootiology
H. cupida is a waterborne organism (Baumann et al. 1972 ). Therefore, the source of
infection was most likely the marine environment.
Pathogenicity
Pathogenicity was confi rmed in laboratory-based experiments involving waterborne
challenge with 10
3 –10
5 cells/ml. Approximately 75 % mortalities were recorded
within 4 days Kusuda et al . ( 1986 ).
Moraxellaceae Representatives
Acinetobacter sp.
Characteristics of the Disease
During Autumn 1978 when the water temperature was between 8 and 11 °C, an
outbreak of disease occurred in a group of 60 sexually mature Atlantic salmon. The
fi sh, each of 5–12 kg in weight, were wild stock from the River Surma, Norway, and
were held in brackish water during the occurrence of disease. During the 5-week
period of disease, the cumulative mortalities 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 fi ns. Ulceration developed. Lesions appeared in the kidney, liver and spleen, and
small haemorrhages occurred in the air bladder and on the visceral peritoneal surfaces (Roald and Hastein 1980 ).
Isolation
Pure cultures were recovered on 5 % (w/v) blood agar supplemented with 0.5 %
(w/v) sodium chloride, following incubation at 22 °C for 48 h. Thus, blood, kidney,
liver, spleen and ulcers in the muscle appeared to contain dense bacterial populations. Pure cultures were obtained, which were capable of reproducing the infection
during laboratory-based studies (Roald and Hastein 1980 ).
Moraxellaceae Representatives