Bull.Eur. Ass.Fish parhol. J (4),j7, 1995

HITRA-DISEASE,A CONFUSINGCONCEPT By O. Sor-Eru

In articles, papers, meetings and dis- The name "cold-water vibriosis', cussions- both in and other clearly saysthat the diseaseis causedby a countries- a number of scientistshave Vibrio spp. describedthe -diseasefrom totally The disagreementamong the scientists different points of view. No wonder that was reflected in the program for the 2nd unitiated observerslook upon this so far Int. Conf. of EAFP in Montpellier, where typical, Norwegian fish disease, as the Hitra-diseasewas presentedfirst as an mystifying. Or, as a colleagueasked me: environmental and nutritional disease "What is the problem? Is the Hitra- ("haemorrhagic syndrome") and the next disease so difficult to understand day as a vibriosis,just like in Plymouth 2 comparedto other diseases,or does one years ago. Has there been no progress in have to look for the solution among the clarifying the causeof the disease- or is scientiststhemselves? " it only a question of using the wrong He obviously referred to the fact that words? the disrase has got 3 different names: "The haemorrhagicsyndrome group" "Hitra-diseasel' "haemorrhagic stressesthe importance of running fish syndrome" and "cold-water vibriosis]' farms in the correct way: proper food, no and that the namesare related to different stress, good water etc. As far as I know explanations and descriptions. He also there is no disagreementon this. There wondered if it is necessaryto relate fish also seems to be an extensive diseaseresearch projects to the Hitra- comprehensionthat all kinds of stress disease to get financial support in make the fish more vulnerable to Norway. infectious diseases.So why relate stress "Hitra" is the name of an island south- factors to the Hitra-diseasein particular? westof the city of . The name What about vibriosis, furunculosis, "Hitra-disease" tells us that some years ERM, BKD etc.? It is also acceptedthat ago therewere outbreaks of the diseasein one can easily frighten fish to death and this region. After having spread along they will die with internal and external most of the Norwegiancoast, it is difficult haemorrhages,i.e. with symptoms very to understandwhy this name is still in use much like those found in Hitra-diseased - it tells us nothing about the disease fish. itself. If the Hitra-diseasemainly is a stress- "Haemorrhagic syndrome" tells us induced disease,why isn't it found in that the diseaseleads to bleedingsand that other countries?Are thesecountries' fish the cause of the diseaseis obscure and farmers so much better, is their fish food perhaps manifold - or that one yet of much better quality, or is there some hasn't found the explanation. other reason?Why did the diseasespread Bull. F.ur.Ass. FishPathol S (4), 78' 1985

without consideringthe possibility along the Norwcgiancoast in the way it clisease fish suflering from stressmay show did? Yet I have not lound answers to that same kind of symptoms as do fish these questions unlcss the disease is the by the so-calledHitra-bacterium' reiateclto a bacterialinfectioti' iniected the time has come for a close Having lolloweti thc cxterlsiveand I think clarifying discussionon all aspects thoroughwork o1'the"bacteria group" it and ttre Hitra-disease' Why not sreemsclear lo me that we are dealingwith concerning start with the name? a diseasecaused by infection' ln addition haemorrhagic syndrome be the to infectedfish we also now and then find I-et when no related microorganism is fisli suffering from a so-calledsyndrome narne found. One should herehave in mind that causedby bad husbandry conditions' is quite normal for a healthy fish to A parallelin human beingsis that when it carry a great number of different we arewet and getcold feetwe often catch bacteria in the peritoneal fluid a cold. But we will not be diseased harmless - on the skin. without bacteria. ln other words bad and On the other hand - is it well con- conditions make us more susceptibleto to call the bacterialinfection cold- infections. sidered water vibriosis? It may be mistaken for Now a few words about the name of the the ordinary vibriosis' What about Hitra- clisease.Why does everyonewish to call vibriosis?Or somethingelse? tfteir diseaseHitra-disease? It would be a discussions and arguing weli establishedthat Despite the pity if the name is so group" will "the haemorrhagicsyndrome it is impossibleto get rid of it' Anyway' go on with their work, and continuously the name is, in most PeoPle'sminds' iind b"tt.. methods for making the fish relatedto symptoms' Another parallel in more resistant to all diseases'This is human beings:I iravea headache'It may probably the most important work in be causeclby a tumor, an inflammation' a salmon farming research in NorwaY stroke,wrong glasses,a hangoveretc' But today. At the sametime I'tn sure that.the is headachethe nameof thedisease or is it "bacteria group" will finally succeed.ln a symptom?The answeris obvious' their attempts to produce a vacclne In the discussionsabout the Hitra- againstthe "cold-water vibriosisl' cliseasethere seemsto be a faint touch of Best wishesfor the work to be done' prestigein calling"rny disease"the Hltra-

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