In 1893, Canestrini[4] made pioneering observations on epizootics among migrating eels (Anguilla vulgaris), noting their association with a bacterium he termed Bacillus anguillarum.
[1][4][5] Canestrini meticulously documented the clinical signs exhibited by infected eels, laying the groundwork for further investigations into the pathogenic nature of this bacterium.
Expanding upon Canestrini's work, Bergman's description in 1909[1][5][6] provided a comprehensive account of Vibrio anguillarum as the etiological agent responsible for the 'Red Pest of eels' in the Baltic Sea.
However, Holt documented epizootic outbreaks of vibriosis in rainbow trout reared in seawater, causing substantial mortality in affected populations.
Holt's investigations revealed a range of disease manifestations associated with vibriosis, including sudden mortality and varied pathological findings upon necropsy.
[1][5][6] These findings highlighted the severity and diversity of symptoms observed in affected fish populations, emphasizing the need for further research into disease prevention and control strategies.
[1] Most V. anguillarum strains were found to be able to ferment glucose, fructose, galactose, mannitol, mannose, maltose, sucrose, trehalose, dextrin, glycogen, chitin and ONPG.
[8] The iron uptake system is negatively controlled by the Fur protein, which is chromosomally encoded and represses transcription by binding to and bending the DNA.
[26] The discovery of a metalloprotease with mucinase activity, and a severe reduction in virulence in its absence, suggest its use in penetrating the host fish’s protective mucus layer.
[31] EmpA metalloprotease is a main factor involved in tissue damage and destruction during infection in salmonids, similar to other proteases produced by pathogenic bacteria.
[31] Conditioned cells from an empA mutant strain were found to induce protease activity which suggests the presence of an unidentified autoinducer.
[31] Although typically not associated with disease in humans, in 2017 an immunocompromised woman died in hospital from sepsis and multiorgan failure and laboratory tests confirmed the presence of Vibrio anguillarum in her blood.
The behavior of Vibrio anguillarum is intricately linked to environmental factors, including temperature, iron availability, and water conditions, which play pivotal roles in its pathogenicity and disease management.
This temperature-dependent expression of virulence factors underscores the significance of understanding how environmental cues shape the pathogenicity of Vibrio anguillarum, particularly in the context of aquaculture practices conducted in varied temperature regimes.
When iron levels are low, Vibrio anguillarum undergoes significant metabolic adjustments, leading to an increase in the expression of genes associated with virulence.
Factors like salinity, nutrient availability, water flow, oxygen levels, and biofilm presence affect Vibrio anguillarum's survival, growth, and virulence, impacting disease spread among aquatic organisms.
[23][24] Diligent monitoring and maintenance of optimal water conditions are vital aspects of disease control strategies, fostering the well-being and productivity of aquaculture operations while reducing the impact of bacterial pathogens.