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[[Category:To Do - Steph]]
Caused By – ''Streptococcus iniae''
==Introduction==
Streptooccosis in fish is most commonly caused by the '''gram positive, facultative anaerobe [[Bacteria|bacterium]]''', ''Streptococcus iniae''. It does not fit any Lancefield serotype groups but is '''beta-haemolytic on blood agar'''. Other species may be involved including ''[[Enterococcus faecalis|S. faecalis]], E. seriolicida, S. faecium, S. difficile,'' and ''S. agalactiae''.
''S. iniae'' has also been identified as an '''emerging human pathogen producing soft tissue infections''' in people.<ref>Fuller, J. D., Bast, D. J., Nizet, V., Low, D. E., de Azavedo, J. C (2001) '''Streptococcus iniae virulence is associated with a distinct genetic profile'''. Infection and Immunity, 69</ref> The risk is mainly to direct handlers of infected fish and is not thought to be food-borne.
==Distribution==
Asia, South Africa, USA, Australia, Italy and Spain.
==Signalment==
There are reports of streptococcosis in '''marine, brackish and freshwater''' fish. It can also affect dolphins.
Infection appears during the '''Summer''' in periods of warmer water temperatures.
Other predisposing factors include high stocking density and stressors.
==Clinical Signs==
''S. iniae'' causes '''meningoencephalitis, systemic septicaemia and subsequent mortalities''' in fish, particularly cultured species.
Affected fish display '''bilateral exopthalmos and distension of the eyes''' giving their heads a strange shape. Internal and external '''haemorrhages may be grossly visible and skin is often darkened'''. Fish are lethargic, anorexic and stop feeding. They '''swim listlessly''' and exhibit strange behaviour.
==Diagnosis==
Diagnosis is usually based upon clinical signs and histopathological findings.
The bacterium grows very well on '''brain-heart infusion agar, nutrient agar, blood agar and Todd-Hewitt agar'''. It can then be biochemically characterised by '''[[Fluorescent antibody testing]] (FA) or PCR.'''
Histopathologically, '''meningitis and panopthalmitis with cellular infiltration''' of the eye is evident.
On necropsy, '''exopthalmia is evident, petechiation''' common on the inside of the opercula and congestion of the pectoral and caudal fins and mouth. '''Ascites, hepatomegaly, splenomegaly and organ congestion''' are often noted.
Clinical signs and pathology are very similar to those of enterococcal infection.
==Treatment==
'''Amoxycillin, Erythromycin and Oxytetracycline''' can be used but resistance is a problem with all except erythromycin.
'''Vaccination''' can also be used as a treatment.
==Control==
A '''vaccine, administered intraperitoneally''' is available, derived from '''formalin killed whole cells''' but provides only short-term protection for '''6 months'''.
{{Learning
|flashcards = [[Streptococcosis in Fish Flashcards]]
}}
==References==
<references/>
Animal Health & Production Compendium, '''Streptococcus iniae datasheet''', accessed 13/07/2011 @ http://www.cabi.org/ahpc/
Animal Health & Production Compendium, '''Streptococcosis in fish caused by Streptococcus iniae datasheet''', accessed 13/07/2011 @ http://www.cabi.org/ahpc/
[[Category:To Do - CABI review]]