También conocido como: Enfermedad Bacteriana del Riñón –- Corynebacterial Kidney Disease -– Dee Disease –- Salmonid Kidney Disease -– White Boil Disease
Renibacterium salmoninarum es una bacteria gram-positiva, rod shaped, non spore forming intracellular y causa Enfermedad Bacteriana del Riñon (EBR) en peces salmónidos.
BKD is usually a chronic disease and causes mortality in juvenile fish and pre-spawning adults. Due to its prevalence, it has a significant impact upon both farmed fish and conservation efforts in wild endangered species. Its production of chronic granulomata within the tissues is similar to that caused by Mycobacteria spp. in mammals.
Esta enfermedad no es zoonótica.
América del Norte, Reino Unido, Europa Continental, Japón, Chile y Scandinavia.
Most outbreaks have occurred in fish culture facilities. As the bacteria are often enzootic in wild populations and waterborne, transmission to captive fish is often a concern.
Salmonids of the Onchorhynchus, Salmo and Salvelinus genera appear to be the primary hosts and many other species can acquire natural infections. The organism is highly adapted to both infectivity and persistence in these hosts. Its intracellular nature provides it with both a nutrient source and method of evasion from the host immune response.
Some fish show no, few or very subtle external signs of BKD. Pocos signos externos.
Affected fish may be lethargic, pale around the gills and may have exopthalmos. Haemorrhagic lesions may be visible around the vent or on the skin, fins and musculature. Cystic cavities may be visible within the musculature.
Fish with BKD are often found to be anaemic with a 49-66% decrease in circulating erythrocytes, which are of a smaller size and have increased sedimentation rates. Bilirubin, Blood Urea Nitrogen and Potassium also increase. 
Diagnosis most commonly relies on direct detection of bacteria or antigens rather than antibodies as the latter are both difficult to measure and an unreliable indicator of infection status.
This can be achieved using culture, ELISA, and PCR. The organism can be cultured on cysteine blood enriched medium. Isolation can take 2-19 weeks and is often contaminated as the organism is very slow growing. Kidney tissue should not be used for culture as it is inhibitory to in-vitro growth of R. salmoninarum. The bacterium can be located in tissue sections using periodic acid-Schiff stain, but FAT is more sensitive and therefore can allow visualisation of bacterial cells in subclinical infections. Several methods can then be used to attempt to quantify the degree of infection.
The most widely used antigen detecting test used in large surveys are dot-blot and ELISA. ELISA allows precise quantitative detection while dot-blot is qualitative. ELISA is thought to be as sensitive as culture of IFAT, if not more so. It may however be affected by cross-reactivity with other antigens and this is poorly understood at present. Its sensitivity and specificity also rely on the quality of the antisera used. It is therefore recommended that diagnosis is supported by another diagnostic test.
PCR is often used as a confirmatory test and is both rapid and sensitive, but equipment and sampling criteria make it impractical for use on a large scale.
Antigens can also be detected by immunodiffusion or counterimmunophoresis, from kidney, liver, spleen and blood. The former two tissues are most useful. Counterimmunphoresis is rapid, taking only 1.5h and is also capable of detecting low levels of R. salmoninarum such as in subclinical infections.
Necropsy findings usually include white-grey necrotic patches and granulomatous inflammation of most commonly the kidneys, also the spleen and liver, and sometimes other viscera. The kidneys may also be swollen and oedematous. Bloody fluid may have accumulated in the body cavities. Musculature is also often necrotic. Granulomas vary slightly in their nature according to the species of fish affected.
Erythromycin and Oxytetracycline are the antibiotics of choice, both can be injected and oxytetracycline is also available in an oral formulation. Erythromycin resistance is increasing however. Both can be used in fry and broodstock.
An intraperitoneal vaccine is also available and can be used as a treatment in the face of an outbreak of BKD.
Avoidance is key – this can be difficult due to exposure of captive fish from waterborne bacteria shed by feral fish upstream of hatcheries.
Segregation or culling of broodstock is now often used to ensure a source of egg lots and thus juvenile fish  with no or very low levels of R. salmoninarum. It is poorly understood what other impacts segregation may have at this point. Contaminated premises may need to be emptied and restocked with BKD-free fish.
Regular fallowing may help to break the disease cycle.
Una vacuna intra-peritoneal esta disponible pero solo se puede utilizar en peces de más de 10g de peso.
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