Developments in the control of bacterial kidney disease of salmonid fishes (original) (raw)
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BACTERIAL KIDNEY DISEASE (BKD) IN MICHIGAN SALMONIDS
Bacterial Kidney Disease (BKD) caused by a Gram-positive bacterium, Renibacterium salmoninarum (R. salmoninarum) is a systemic disease that threatens the expansion of both cultured and wild salmonines worldwide. Historical records show that BKD affected Michigan’s brook trout as early as 1955 (Allison 1958) and continued its spread to most of other salmonid species such as coho salmon (Oncorhynchus kisutch) spawners in the late sixties (MacLean and Yoder 1970) followed by a potent epizootic among the chinook salmon (Oncorhynchus tshawytscha) populations in Lake Michigan in the late 1980’s (Holey et al. 1998). Despite the magnitude of the setback to fisheries conservation efforts in Michigan, relatively little research has been done on R. salmoninarum, primarily due to its slow-growing nature, which takes up to 12 weeks to obtain growth upon primary isolation. The tissue processing protocol and optimized culture technique developed in this study, has facilitated the isolation of large number of R. salmoninarum and achieved a remarkably shorter incubation time for primary isolation. A sort of disagreement in results among the three used diagnostic assays (nPCR, Culture, Q-ELISA) was recorded during BKD testing of the feral and captive salmonid stocks for BKD, which may reflect the different phases of R. salmoninarum infection at the time of sampling. Further, the testing results demonstrated the presence of six patterns, with each of the patterns representing a probable stage along the course of R. salmoninarum infection. Data also demonstrated that male spawner salmon play the same role played by female in transmission of R. salmoninarum by shedding of the bacteria and its soluble antigens in milt. Moreover, results revealed that Hinchenbrook coho strain is more susceptible to R. salmoninarum than the Michigan adapted coho salmon strain. Data also, supported the previous reports, which indicated that brook trout are highly susceptible to BKD. Also, data showed that prevalence of R. salmoninarum in the hatchery-raised brook trout is the same as wild strains residing in the water source and that Iron River brook trout are more vulnerable to R. salmoninarum infection than Assinica strain. Last, external parasites could played a possible role in initiation, speeding up the R. salmoninarum infection and BKD occurrence and mortalities is not related to changes in seasons. Finally, findings indicated that the adult parasitic sea lamprey is a new host range for R. salmoninarum where the bacteria were isolated from the kidneys of a number of sea lampreys from Lake Ontario in 2003 and 2004.
Journal of Aquatic Animal Health, 1989
We challenged duplicate groups of yearling smolts of Chinook salmon Oncorhynchus tshawytscha held in seawater with an intraperitoneal inoculation of the kidney disease bacterium Renibacterium salmoninarum I d before and at intervals of 1, 11, and 29 d after a 21-d oral administration of erythromycin thiocyanate at 0.1 g/kg body weight per day. Most mortality attributable to bacterial kidney disease (BKD) in fish challenged with R. salmoninarum but not administered erythromycin occurred 2-3 weeks after challenge; the average survival 35 d after challenge was only 9%. Nearly 70% of the fish challenged 1 d before the erythromycin feeding were alive 35 d after the 21-d treatment, and more than 98% of the fish challenged the day after the 21-d erythromycin treatment survived a further 35 d. Fish challenged 29 d after the erythromycin treatment were not significantly protected against BKD. Chinook salmon that were not challenged with the bacterium but were injected with sterile phosphate-buffered saline and then fed a ration with erythromycin survived at a significantly higher rate than unchallenged fish injected with saline but not fed erythromycin. Fish that were not injected with saline or R. salmoninarum survived at a significantly higher rate than fish handled and injected with saline or pathogen. Because erythromycin protected fish challenged just before and immediately after treatment, the antibiotic should be useful early in an outbreak of BKD and as a prophylactic when stresses are expected.
Journal of Aquatic Animal Health, 1989
We challenged duplicate groups of yearling smolts of Chinook salmon Oncorhynchus tshawytscha held in seawater with an intraperitoneal inoculation of the kidney disease bacterium Renibacterium salmoninarum I d before and at intervals of 1, 11, and 29 d after a 21-d oral administration of erythromycin thiocyanate at 0.1 g/kg body weight per day. Most mortality attributable to bacterial kidney disease (BKD) in fish challenged with R. salmoninarum but not administered erythromycin occurred 2-3 weeks after challenge; the average survival 35 d after challenge was only 9%. Nearly 70% of the fish challenged 1 d before the erythromycin feeding were alive 35 d after the 21-d treatment, and more than 98% of the fish challenged the day after the 21-d erythromycin treatment survived a further 35 d. Fish challenged 29 d after the erythromycin treatment were not significantly protected against BKD. Chinook salmon that were not challenged with the bacterium but were injected with sterile phosphate-buffered saline and then fed a ration with erythromycin survived at a significantly higher rate than unchallenged fish injected with saline but not fed erythromycin. Fish that were not injected with saline or R. salmoninarum survived at a significantly higher rate than fish handled and injected with saline or pathogen. Because erythromycin protected fish challenged just before and immediately after treatment, the antibiotic should be useful early in an outbreak of BKD and as a prophylactic when stresses are expected.
1991
(U of I) Principal Investigator and lead scientist of project, responsible for overall coordination, experimental design, logistics and reporting. Expertise in microbiological assay for erythromycin, tissue residues of erythromycin in juveniles, hatchery injection protocols, erythromycin feeding trials, efficacy of erythromycin against bacterial kidney disease, and diagnostics and culture of bacterial kidney disease. Theodore C. Bjornn:(U of I). Co-investigator, Fish Biology. Expertise in experimental design, hatchery logistics, feeding trials, efficacy of erythromycin against bacterial kidney disease. William Hayton, (WSU) Co-investigator, Pharmacology. Expertise in pharmacokinetic modeling of drugs and other compounds administered to fish and other vertebrates. Research Associates and Laboratory Technicians Gwynne L. Chandler-(Research Associate U of I) Fish biology Analytical and wet laboratory coordination, data analysis and computer graphics. Hatchery injections and tissue sampling. Cheryl Hughett (Laboratory Technician, U of I). Microbiology Analytical laboratory erythromycin assay Janine Nesheim (Laboratory Technician, U of I). Microbiology Analytical laboratory erythromycin assay, ELISA, FAT, Culture of R e n i b a c t e r i u m s a l m o n i n a r u m Rudy R. Ringe (Research Associate, U of I). Fish Biology Wet laboratory logistics and fish life support systems. Transportation of adult and juvenile fish. Hatchery injection, spawning and tissue sampling.
A number of clinical Bacterial Kidney Disease (BKD) outbreaks caused by Renibacterium salmoninarum infection among the hatchery reared brook (BKT) trout lots were presented during 2002-2004 to the Aquatic Animal Health Laboratory, Michigan State University, MI, USA. Diagnosis of these mortality episodes was performed thorough clinical examination, quantitative enzyme linked immunosorbant assay (Q-ELISA), nested polymerase chain reaction (nPCR), culture, histopathology and immunohistochemistry (IHC). The possible causes that lead to the initiation and progression of such outbreaks have been investigated. Although Q-ELISA, nPCR and culture results for all of the examined cases indicated a heavy infection with R. salmoninarum inconsistent results were obtained by histopathology and immunohistochemical examination of the paraffin embedded blocks of the formalin fixed kidney tissues. This study also included assessment of R. salmoninarum infection status in a subsample of BKT broodstocks of the same hatchery. Results indicated the presence of chronic infection in the broodstock with BKDpathognmonic granulomas occupying fairly large portions of the kidney tissues.
Pathogens, 2020
Bacterial Kidney Disease, caused by Renibacterium salmoninarum (Rs), is widespread and can cause significant mortality at most life stages in infected salmonids. Rs is commonly found in inland trout, which can be carriers of the bacterium. Lethal spawns can be used to control vertical transmission to progeny through the culling of eggs from infected parents, but can be costly, time-consuming, and can negatively impact important and rare brood stocks. Erymicin 200 is an Investigational New Animal Drug (INAD) intended to reduce Rs levels in hatchery brood stocks and control vertical transmission to progeny. We tested the efficacy of Erymicin 200 injections in a positive, hatchery-resident rainbow trout (Oncorhynchus mykiss) brood stock in Colorado, USA. Brood fish age two and three were injected with 25 mg per kg of body weight Erymicin 200 three times prior to spawning. Erymicin 200 was effective in reducing Rs to below detectable levels in treated fish. However, both negative treate...
Aquaculture, 2000
We evaluated the use of feed restriction to decrease mortality and infection rates in yearling Ž. chinook salmon Oncorhynchus tshawytscha naturally infected with Renibacterium salmoni-Ž. narum, the causative agent of bacterial kidney disease BKD. Fish were purposely stressed and then fed either full ration, half ration, or fasted. At the termination of the 6-week experiment, feed intake of the fish was evaluated by X-radiography after feeding all groups in excess and the amount of BKD p57 antigen in the kidneys was measured by enzyme linked immonosorbent assay Ž. ELISA to assess effects of infection on feeding rates. Only a few individuals in each treatment died during the experiment, but the proportion of fish with detectable antigen concentration increased as ration level decreased. Within each treatment, fish with undetectable concentrations of p57 antigen ate significantly more than fish with elevated antigen levels. Exponential regressions were fitted for each ration level describing the decrease of appetite as levels of antigen concentrations increased. The data indicate that even fish that were quite sick as judged from their q Oregon Agricultural Experiment Station Technical Report No. 11610.
Aquaculture
This study describes the success of broodstock culling in controlling Renibacterium salmoninarum infection on two sea ranches in Iceland. On both ranches, the overall percentage of positive broodfish was around 35% when the program was initiated. After a few years of broodstock culling, the prevalence figures for broodfish declined and remained below 2.0%. The progeny of the fish subjected to culling, sampled during smoltification, always tested negative for R. salmoninarum. As infected broodfish were detected in most years, there was a continuous risk of bacterial kidney disease (BKD) epidemics on both ranches.