524
to improved growth, immunostimulation and resistance to challenge (Samad et al.
2014 ).
Antimicrobial Compounds Colorni et al. ( 1981 ) achieved success with chloramphenicol, dosed at 50 mg of drug/kg body weight of fi sh/day for an unspecifi ed
period, and nitrofurantoin (50 mg/l of water/1 h), both of which alleviated mortalities. However, we would caution against the use of chloramphenicol in fi sheries, in
view of the report of the Swann Committee (Report 1969 ). In essence, chloramphenicol should be restricted to use in human beings.
Vibrio anguillarum
Characteristics of the Disease
The causal agent of ‘red-pest’ in eels was fi rst isolated by Canestrini ( 1893 ), who
designated the organism as Bacterium anguillarum. A further case among eels in
Sweden during 1907 was investigated by Bergman ( 1909 ), and it was directly attributable to this scientist that the name of V. anguillarum was coined. ‘Red-pest’
(referred to historically as pestis rubra anguillarum erysipelosis anguillarum)
caused catastrophic losses among eels held in sea water sites within Italy during the
eighteenth and nineteenth centuries. The excellent description of an outbreak of
‘red-pest’ in eels during 1718 is undoubtedly the fi rst reference to a bacterial fi sh
disease in the European literature (Bonaveri 1761 ). For a detailed account of the
early narratives, reference is made to the splendid review of Drouin de Bouville
( 1907 ). However, confusion may result from the multiplicity of names used to
describe the disease. Thus, references may be found to ‘salt-water furunculosis’
(Rucker 1963 ), ‘boil-disease’ (Kubota and Takakuwa 1963 ), ‘ulcer-disease’ (Bagge
and Bagge 1956 ) and ‘Hitra-disease’ (Egidius et al. 1981 ), as well as to the universally accepted name of ‘vibriosis’.
Apt but gory descriptions have been made about the nature of vibriosis in fi sh. To
microbiologists, the disease may be regarded as yet another haemorrhagic septicaemia (Fig. 10.4 ). Typically, infected fi sh show skin discoloration, the presence of red
necrotic lesions in the abdominal muscle, and erythema (bloody blotches) at the
base of the fi ns, around the vent, and within the mouth (in this respect there is a
resemblance to ERM, caused by Yersinia ruckeri). The gut and rectum may be distended, and fi lled with clear viscous fl uid. Exophthalmia may be evident (Anderson
and Conroy 1970 ).
In Pacifi c salmon fi ngerlings, a bacteraemia occurs in the initial stages of disease. From histological examination, it may be concluded that there are pathological changes in the blood, connective tissue, gills, kidney, liver (an anaemia) and
posterior gastro-intestinal tract, and swelling in the spleen. The bacterial cells
appear to be uniformly distributed throughout the affected tissues, although the
10 Vibrios
to improved growth, immunostimulation and resistance to challenge (Samad et al.
2014 ).
Antimicrobial Compounds Colorni et al. ( 1981 ) achieved success with chloramphenicol, dosed at 50 mg of drug/kg body weight of fi sh/day for an unspecifi ed
period, and nitrofurantoin (50 mg/l of water/1 h), both of which alleviated mortalities. However, we would caution against the use of chloramphenicol in fi sheries, in
view of the report of the Swann Committee (Report 1969 ). In essence, chloramphenicol should be restricted to use in human beings.
Vibrio anguillarum
Characteristics of the Disease
The causal agent of ‘red-pest’ in eels was fi rst isolated by Canestrini ( 1893 ), who
designated the organism as Bacterium anguillarum. A further case among eels in
Sweden during 1907 was investigated by Bergman ( 1909 ), and it was directly attributable to this scientist that the name of V. anguillarum was coined. ‘Red-pest’
(referred to historically as pestis rubra anguillarum erysipelosis anguillarum)
caused catastrophic losses among eels held in sea water sites within Italy during the
eighteenth and nineteenth centuries. The excellent description of an outbreak of
‘red-pest’ in eels during 1718 is undoubtedly the fi rst reference to a bacterial fi sh
disease in the European literature (Bonaveri 1761 ). For a detailed account of the
early narratives, reference is made to the splendid review of Drouin de Bouville
( 1907 ). However, confusion may result from the multiplicity of names used to
describe the disease. Thus, references may be found to ‘salt-water furunculosis’
(Rucker 1963 ), ‘boil-disease’ (Kubota and Takakuwa 1963 ), ‘ulcer-disease’ (Bagge
and Bagge 1956 ) and ‘Hitra-disease’ (Egidius et al. 1981 ), as well as to the universally accepted name of ‘vibriosis’.
Apt but gory descriptions have been made about the nature of vibriosis in fi sh. To
microbiologists, the disease may be regarded as yet another haemorrhagic septicaemia (Fig. 10.4 ). Typically, infected fi sh show skin discoloration, the presence of red
necrotic lesions in the abdominal muscle, and erythema (bloody blotches) at the
base of the fi ns, around the vent, and within the mouth (in this respect there is a
resemblance to ERM, caused by Yersinia ruckeri). The gut and rectum may be distended, and fi lled with clear viscous fl uid. Exophthalmia may be evident (Anderson
and Conroy 1970 ).
In Pacifi c salmon fi ngerlings, a bacteraemia occurs in the initial stages of disease. From histological examination, it may be concluded that there are pathological changes in the blood, connective tissue, gills, kidney, liver (an anaemia) and
posterior gastro-intestinal tract, and swelling in the spleen. The bacterial cells
appear to be uniformly distributed throughout the affected tissues, although the
10 Vibrios