It means that vibriosis is most frequently caused by
Listonella anguillarum, or in the pantheon of causes of vibriosis,
Listonella anguillarum is the most important, or that the most severe (and thus important) cases of vibriosis are caused by
Listonella anguillarum:
eˇtiˇolˇoˇgy n.
- The study of causes or origins.
- The branch of medicine that deals with the causes or origins of disease.
etiˇoˇlogiˇcal adj.
- of or relating to the philosophical study of causation
- relating to the etiology of a disease; "etiological agent"
aˇgent n.
- One that acts or has the power or authority to act.
- One empowered to act for or represent another: an author's agent; an insurance agent.
- A means by which something is done or caused; instrument.
- A force or substance that causes a change: a chemical agent; an infectious agent.
- A representative or official of a government or administrative department of a government: an FBI agent.
- A spy.
- Linguistics The noun or noun phrase that specifies the person through whom or the means by which an action is effected.
You could as easily say "
Listonella anguillarum is the most important cause of vibriosis."
Why it is the "most important" is undefined in the sentence -- "most important", as I said above, could be due to the frequency with which
Listonella anguillarum is found to be the cause of vibriosis compared to other causes, or the severity of the vibriosis caused by
Listonella anguillarum as opposed to the severity of the disease when caused by other agents.