Red mouth search

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The red mouth disease ( Enteric Redmouth Disease or ERM, Salmonid Blood Spot ) is a generalized, acute or chronic infectious disease caused by the bacterium Yersinia ruckeri , to which salmonids , especially rainbow trout, are susceptible. She belongs to the Yersinios .

The disease was first diagnosed in rainbow trout by R. Rucker in the early 1950s in Hagerman Valley , Idaho , USA . Many fish carry the pathogen Yersinia ruckeri as a symptom-free carrier until it leads to high losses under stress, triggered by poor housing or water conditions. Gram-negative , flagellated, slightly curved rod bacteria were isolated from the kidneys of diseased animals , which were only assigned to the genus Yersinia in 1978 .

causes

The size of the fish plays a decisive role in the outbreak of the disease. Fish up to 10 cm in size are particularly susceptible to the bacterium. In larger animals, the disease takes a more chronic course up to epidemic outbreaks, which have been described in animals 17 to 20 cm and 29.5 cm in length. Against this background, however, as with most fish diseases, stress factors are the decisive factor, which then lead to the outbreak of the disease. In addition to the actual susceptibility of the host and the virulence of the pathogen, these are too high a stocking density, feed changes, poor water quality with high ammonium and / or low oxygen content or transport of the animals.

With the addition of copper , in non-lethal doses, the susceptibility of the fish to ERM is higher than that of the control animals. According to research, there is no seasonal dependence on the onset of the disease. An epidemic ERM outbreak usually begins gradually, the incubation period is around one week, but depends on the housing conditions. Mortality is low initially but increases over time and large losses can occur if countermeasures are not taken.

infection

Yersinia ruckeri infects fish through the gills and skin through direct contact from fish to fish, but also through contaminated water, equipment and transport containers. Birds can also transmit the bacterium. Yersinia has been detected in the intestinal contents of birds of prey and gulls . Fish that survive this disease can become carriers and thus form a permanent reservoir of pathogens. The bacterium is excreted in the feces of the fish and thus serves as a renewed source of infection for uninfected fish. In recent years, more extensive studies have been carried out, which have shown that Yersinia ruckeri can even survive in brackish water (salinity 0-20 ppt) for at least four months. The germ can survive for more than 100 days in river and lake water as well as sediment.

It has also been found that some Yersinia ruckeri strains have the ability to form a biofilm . This enables them to adhere to solid surfaces in the water and grow, a property that is related to the ability of the bacterium to move through flagella . It increases the resistance and survivability of the bacterium in the water.

Course of disease

The symptoms of the infection are identical to those of other septicemia caused by gram-negative bacteria . A reluctance to eat, dark skin and fatigue are almost always associated with the disease, except in young broods, where deaths without visible signs of disease can occur.

The redness of the mouth and throat is caused by subcutaneous bleeding and is common, but not always present. In the atypical course of the infection, only the skin becomes increasingly dark and the fish swim near the surface of the water. If the disease progresses untreated, erosions can occur on the jaw and roof of the mouth. Bleeding occurs on the surface of the body, the tips of the gills, the bases of the fins, and along the sideline . In later stages of the infection, unilateral or bilateral exophthalmos and bleeding into the eye socket and iris , sometimes to the point of complete opacity of the entire eye, can often be observed.

The animals suffer from insufficient exercise intensity and balance disorders. The blood vessels in the entire peritoneum are congested and bleeding occurs in the liver , pancreas , swim bladder , muscles and adipose tissue . The kidney and spleen are often swollen, and fluid retention in the stomach and intestines can be seen. Ascites and enteritis are other regular findings at the dissection .

Diseases that are similar in clinical picture:

diagnosis

The bacterium can be isolated from numerous tissues, especially from the spleen, kidneys and heart, but also from the liver, gills, eyes, heart blood and changed areas of the oral cavity and cultivated on nutrient media. Using a kidney biopsy , it is possible to take the required sample tissue from living fish.

In the last few years some methods have been developed and improved in order to detect Yersinia ruckeri in very small numbers using the polymerase chain reaction (PCR). It is now not only possible to detect the pathogen in various organs, but also in the blood of infected fish. This provides an opportunity to diagnose the disease without killing the fish.

treatment

In order to prevent an outbreak of red mouth disease, factors that favor disease, such as high stocking density and poor water quality, should be avoided as far as possible. Traces of chemicals or organic material dissolved in the water in connection with high water temperatures and the resulting low oxygen content can provoke outbreaks of disease even with normal population density.

If the disease breaks out , treatment with antibiotics such as oxytetracycline , erythromycin , quinolone antibiotics and potentiated sulfonamides can be carried out with good results.

Red mouth disease is one of the first fish diseases for which an effective commercial vaccine was developed. Vaccination is an effective way of containing the disease. It can reduce the losses caused by the disease and the use of antibiotics for treatment. However, if the fish are kept under poor hygienic conditions, the disease can also break out in vaccinated animals.

Reporting requirement

Like all animal yersinioses in Germany, the red mouth disease of salmonids is one of the notifiable fish diseases and diseases. Monitoring is mandatory in Austria (see animal disease ).

literature

  • E. Amlacher (1992). Paperback of Fish Diseases. Basics of fish pathology . 6th revised edition, Gustav Fischer, Jena, Stuttgart, pp. 149–177. ISBN 3-334-00350-7

Individual evidence

  1. ^ AJ Ross et al .: Description of a bacterium associated with redmouth disease of rainbow trout (Salmo gairdneri) . Can. J. Microbiol. (1966) 12 (4): pp. 763-770 PMID 6007992
  2. ↑ a b M.T. Horne and AC Barnes: Enteric redmouth disease (Yersinia ruckeri). In PTK Woo and DW Bruno (Eds.) Fish Diseases and Disorders , Volume 3: Viral, Bacterial and Fungal Infections. CAB International, 1999, pp. 455-477.
  3. ^ WH Ewing et al .: Yersinia ruckeri sp. nov., the Redmouth (RM) Bacterium. In: Int J Syst Bacteriol 28 (1978), No. 1, pp. 37-44.
  4. ↑ a b M.P. Dulin et al .: 1976. Enteric redmouth disease. Univ. of Idaho, College of Forestry, Wildl. and Range Sci., Bull. 8 (1976)
  5. ↑ a b c d S. Rübsamen and J. Weis: Detection of Enteric Redmouth Disease in rainbow trout, Salmo gairdneri Richardson, in South Baden. In: Tierärztl. Umschau 40 (1985), pp. 995-998.
  6. ↑ a b H. Fuhrmann et al .: An outbreak of enteric redmouth disease in West Germany . In: Journal of Fish Diseases 6 (1983), No. 3, pp. 309-311.
  7. ↑ a b G. N. Frerichs et al .: Atypical infection of rainbow trout, Salmo gairdneri Richardson, with Yersinia ruckeri. In: Journal of Fish Diseases 8 (1985), pp. 383-387.
  8. ↑ MD Knittel: Susceptibility of steelhead trout, Salmo gairdneri Richardson to Redmouth infection (Yersinia ruckeri) Following exposure to copper. In: Journal of Fish Diseases 4 (1981), pp. 33-40.
  9. ↑ JW Warren: Enteric disease Redmouth In: FP Meyeret al .: A guide to integrated fish health management in the great lakes basin. Great Lakes Fishery Commission, Ann Arbor, Michigan 1983
  10. ^ AJ Ross et al .: Description of a bacterium associated with redmouth disease of rainbow trout (Salmo gairdneri). In: Canadian Journal of Microbiology 12 (1966), pp. 763-770.
  11. ^ RL Bangert et al .: A survey of the aerobic bacteria in the faeces of captive raptors. In: Avian Diseases 32 (1988), pp. 53-62.
  12. ^ B. Willumsen: Birds and wild fish as potential vectors of Yersinia ruckeri. In: Journal of Fish Diseases 12 (1989), pp. 275-277.
  13. ^ BK Thorsen et al .: Long term starvation survival of Yersinia ruckeri at different salinities studied by microscopical and flow cytometric methods. In: Applied and Environmental Microbiology 58 (1992), pp. 1624-1628.
  14. ↑ JL Romalde et al .: Starvation-survival processes of the bacterial fish pathogen Yersinia ruckeri. In: Systematic and Applied Microbiology 17 (1994), pp. 161-618
  15. ↑ a b L. Coquet al .: Occurrence and Phenotypic Characterization of Yersinia ruckeri Strains with Biofilm-Forming Capacity in a Rainbow Trout Farm. In: Applied and Environmental Microbiology 68 (2002), pp. 470-475.
  16. ↑ TH Kawula et al .: Using a new inbred fish model and cultured fish tissue-cells to study Aeromonas hydrophila and Yersinia ruckeri pathogenesis. In: Microbial Pathogenesis 20 (1996), pp. 119-125.
  17. ↑ a b H.-J. Schlodtfeldt et al .: Rotmaulseuche / ERM (Enteric Redmouth Disease) of trout and other commercial fish in Northwest Germany - occurrence, therapy and vaccination results. In: Tierärztliche Umschau 40 (1985), pp. 985-995.
  18. ↑ G. Wobeser: An outbreak of redmouth disease in rainbow trout (Salmo gairdneri) in Saskatchewan. In: Journal of the Fisheries Research Board of Canada 30 (1973), pp. 571-575.
  19. ↑ RA Busch: Enteric Redmouth disease (Yersinia ruckeri). In: DP Anderson et al. (Ed.): Antigens of Fish Pathogens. Marcel Merieux, Lyons, 1982, pp. 201-223.
  20. ↑ E. Amlacher: Pocket book of fish diseases. 5th edition, Gustav Fischer, Jena 1986
  21. ↑ EJ Noga et al .: Kidney biopsy a nonlethal method for diagnosing Yersinia ruckeri infection enteric redmouth disease in rainbow trout Salmo gairdneri. In: American Journal of Veterinary Research, 49 (1988), pp. 363-365.
  22. ↑ I. Altinok et al .: Detection of Yersinia ruckeri in rainbow trout blood by use of the polymerase chain reaction. In: Diseases of Aquatic Organisms 44 (2001), pp. 29-34.
  23. ↑ G. Ceschia et al .: The in vitro sensitivity of Yersinia ruckeri to specific antibiotics. In: Journal of Fish Diseases 10 (1987), pp. 65-67.
  24. ^ RA Busch: Protective vaccines for mass immunization of trout. In: Salmonid 1 (1978), pp. 10-22.
  25. ^ B. Austin & DA Austin: Methods for the microbiological examination of fish and shellfish. Chichester, Ellis Horwood 1989.

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