Gastrointestinal Pathogenesis in Aquatic Animals - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 54

Table 3.1 Diseases and aetiological agents that infect, or translocate through, the GI tract of fish.

Pathogen Disease Species affected

Vibrio ( Listonella ) anguillarum Vibriosis Cold water marine fish

Vibrio ordalii Vibriosis Cold water marine fish

Vibrio ( Aliivibrio ) salmonicida Cold water vibriosis Salmonids

Vibrio vulnificus Various

Vibrio ichthyoenteri Larval Japanese flounder

Vibrio harveyi/Vibrio carchariae Infectious gastroenteritis Various marine fish

Aeromonas salmonicida Furunculosis Various

Aeromonas hydrophila Various (stressed)

Yersinia ruckeri Yersiniosis/enteric redmouth Salmonids

Edwardsiella ictaluri Enteric septicaemia of catfish Catfish

Edwardsiella tarda Edwardsiellosis Various

Piscirickettsia salmonis Piscirickettsiosis Various

Pseudomonas anguilliseptica Various

Photobacterium damsela subsp.
piscicida (form. Pasteurella
piscicida )

Pasteurellosis (pseudotuberculosis) Various

Enterococcus/Streptococcus/various Streptococcosis Warm water species

Mycobacterium spp. Mycobacteriosis Various

' Candidatus arthromitus ' Summer enteric syndrome Rainbow trout

The present chapter aims to give an overview of binding, growth and translocation of bacteria
in the digestive tract of teleosts (Table 3.1). (Translocation is migration from the intestinal
lumen through the epithelial mucosa to infect otherwise sterile tissues: Berg 1999.) In addi-
tion, the ability of the bacteria to induce GI inflammation in terms of cytokine expression
is described.

3.2 VIBRIO spp.

Members of the Vibrio genus are Gram-negative curve-shaped rods often isolated from marine
environments and marine animals. Species from this genus, including Vibrio anguillarum
and Vibrio ordalii , are the causative agents of the clinical disease vibriosis. Vibriosis is a
haemorrhagic septicaemic disease which affects both farmed and wild fish, shellfish and
bivalves. Outbreaks of disease generally occur at temperatures above 10 ∘ C. These bacteria are
considered to be part of the environmental and normal bacterial microbiota from apparently
healthy fish (Nayak 2010). At present, Vibrio anguillarum is serotyped into 23 groups
(Pedersen et al. 1999). It has been demonstrated that the two serogroups O1 and O2 are
overall the most important as fish pathogens of Atlantic salmon ( Salmo salar L.), rainbow
trout ( Oncorhynchus mykiss ) and Atlantic cod ( Gadus morhua L.), while O3 has frequently
been isolated from diseased European eels ( Anguilla anguilla ). Strains belonging to the
remaining serogroups are seldom isolated from diseased fish (Pedersen et al. 1999). Other
Vibrio spp. capable of inducing disease of several fish species, such as cultured gilthead sea
bream ( Sparus aurata ), include Vibrio harveyi ( Vibrio carchariae ), Vibrio fischeri, , Vibrio
alginolyticus , Vibrio splendidus and Vibrio ichthyoenteri (García-Rosado et al. 2007). Vibrio
salmonicida is also a reported disease-causing agent in groupers and Atlantic salmon.