Renibacterium (Corynebacterium) salmoninarum Sanders and Fryer, 1980

Common Name: Bacterial kidney disease (BKD), Dee disease

Synonyms and Other Names:

R. salmonina, Corynebacterium salmoninus, corynebacterial kidney disease, salmonid kidney disease

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Identification: Renibacterium salmoninarum is a gram-positive, short, rod-shaped, diplobacillus bacterium that is non-spore-forming, non-motile, and non-encapsulated. Atypical dormant forms may exhibit both rod and coccoid cells. When grown on agar, colonies are opaque, creamy yellow, smooth, shiny, convex and of varying sizes; however, some atypical isolates of resting stages grow as thin grayish layers without colonies (Post 1983; Goodfellow et al. 1985; Austin and Austin 1987; Jonas et al. 2002; Hirvela-Koski et al. 2006).            

Symptoms of BKD in chinook salmon (Oncorhynchus tshawytscha) can include: abdominal fluid build-up and swelling; pseudomembranes on viscera; kidney and gill necrosis; hemorrhaging on viscera and in intestines; ulcers or abscesses in muscles; protruding eyeballs; anemia; blood blisters; and lesions of the eyes, liver, spleen, and heart (Austin and Austin 1987; Holey et al. 1998).

Cells are typically 0.8-2 μm long and >0.45 μm wide. Some atypical isolates from resting stages of the bacterium may be narrower and/or longer. Width is most important in differentiating the two types of cells (Hirvela-Koski et al. 2006).

Size: typically 0.8-2 μm long and >0.45 μm wide

Native Range: Unknown. It is now distributed widely in the northern hemisphere as well as Chile (Thomas et al. 1999). R. salmoninarum was first described from Atlantic salmon (Salmo salar) in Scotland (Austin and Austin 1987).

Map Key
This map only depicts Great Lakes introductions.

Great Lakes Nonindigenous Occurrences: Renibacterium salmoninarum is believed to have been introduced to Lake Michigan when Chinook salmon (Oncorhynchus tshawytscha) stocking began in 1967 (Holey et al. 1998).  The province of Ontario considers this species to be endemic - present in most samples at 1-33% without signs of clinical disease or gross lesions (GLFHC 2015).

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Renibacterium (Corynebacterium) salmoninarum are found here.

State/ProvinceFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
IN200420041St. Joseph
MI1999200822Au Gres-Rifle; Au Sable; Betsie-Platte; Betsy-Chocolay; Boardman-Charlevoix; Brule; Carp-Pine; Cheboygan; Dead-Kelsey; Fishdam-Sturgeon; Lake Huron; Lake Michigan; Lone Lake-Ocqueoc; Lower Grand; Manistee; Manistique River; Millecoquins Lake-Brevoort River; Muskegon; Ontonagon; Pere Marquette-White; St. Joseph; Tahquamenon
NY200420052Lake Ontario; Salmon
WI199820156Beartrap-Nemadji; Door-Kewaunee; Lake Michigan; Lake Superior; Lake Winnebago; Wolf

Table last updated 4/22/2024

† Populations may not be currently present.

Ecology: Occurs in primarily in salmon, trout, and char. It is an obligate fish pathogen and survives intracellularly. It has been recorded from around 13 salmonid species in Europe, North America, and Asia. Genetic diversity amongst isolates within North America is considered relatively low. However, strains isolated from Lake Michigan are found to be more virulent than those from the Pacific Northwest. R. salmoninarum can occur and survive in freshwater and marine environments (Austin and Austin 1987; Starliper et al. 1997; Grayson et al. 1999; Thomas et al. 1999; Jonas et al. 2002).            

The following host species are only somewhat susceptible to BKD and may not necessarily experience mortality upon contracting the disease: lake trout (Salvelinus namaycush), rainbow trout or steelhead (O. mykiss), brook trout (S. fontinalis), lake whitefish (Coregonus clupeaformis), and bloater (C. hoyi). Other host species are relatively more susceptible to BKD and more prone to experiencing mortality due to the disease: coho salmon (O. kisutch), domestic Atlantic salmon (Salmo salar), and chinook salmon (O. tshawytscha) (Starliper et al. 1997; Jonas et al. 2002; Hay 2003; Nuhfer et al. 2005). Occurrences as far north as the Northwest Territories have been recorded in wild Arctic charr (Salvelinus alpinus) and lake trout (S. namaycush) (Souter et al. 1987).             Species other than salmonids are capable of acting as reservoirs that harbor this bacterium, although their potential role in contributing to transmissions is unknown. R. salmoninarum has recently been isolated from sea lamprey (Petromyzon marinus) kidneys in the Lake Ontario watershed (Eissa et al. 2006). Pacific hake (Merluccius productus) has been recorded carrying this bacterium in the wild in coastal areas of British Columbia (Kent et al. 1998), and Pacific herring (Clupea harengus pallasi) in B.C. fish hatcheries is also capable of harboring it (Paclibare et al. 1988).            

Growth of R. salmoninarum is optimal at 10–20ºC and pH of 5.8–7.8, and does not occur at 30–37ºC. Transmission can occur vertically from adult fish to eggs or horizontally from one fish to another. R. salmoninarum can only survive outside hosts in the water column for short periods of time. It is probably capable of forming an inactive or dormant stage in host fish, after which it can either lyse or reactivate depending on changes in abiotic conditions. It probably resides in the kidneys or the digestive tracts of fish hosts for long periods of time. When hosts undergo stress, contracting other infections, sustaining digestive tract or kidney damage, experiencing starvation or undernourishment, undergoing temperature shock, or experiencing crowding, R. salmoninarum may multiply in the kidneys of the host and lead to BKD (Goodfellow et al. 1985; Austin and Austin 1987; Brown et al. 1994; Holey et al. 1998; Thomas et al. 1999; Hirvela-Koski et al. 2006).

Means of Introduction: Renibacterium salmoninarum was introduced unintentionally with introduced salmonids to the Great Lakes system (Bronte et al. 2003).

Status: Considered established where recorded.

Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...


Renibacterium salmoninarum has a high environmental impact in the Great Lakes.


Great Lakes native salmonid species that have tested positive for the bacterium include Atlantic salmon (Salmo salar), lake trout (Salvelinus namaycush), brook trout (S. fontinalis), and splake (S. fontinalis x S. namaycush) (GLFHC 2006, GLFHC 2012, Hay 2003, Jonas et al. 2002, Nuhfer et al. 2005, Starliper et al. 1997). Lake trout and brook trout are considered less susceptible to R. salmoninarum infection and may not experience mortality upon contracting BKD; in contrast, Atlantic salmon are more susceptible and prone to mortality (Hay 2003, Jonas et al. 2002, Nuhfer et al. 2005, Starliper et al. 1997).

Other Great Lakes native species found harboring R. salmoninarum include lake whitefish (Coregonus clupeaformis), bloater (C. hoyi), lake herring (C. artedi), mottled scuplin (Cottus bairdi), white sucker (Catostomus commersonii), muskellunge (Esox masquinongy), channel catfish (Ictalurus punctatus), lake sturgeon (Acipenser fulvescens), and walleye (Sander vitreus) (COSEWIC 2005, GLFHC 2006, GLFHC 2012, Hay 2003, Jonas et al. 2002, Nuhfer et al. 2005, Starliper et al. 1997). Four of the Great Lakes native species (splake, muskie, channel catfish, and lake sturgeon) represent new detections since 2005. Lake whitefish and bloater are believed to be less susceptible to R. salmoninarum infection and may not experience mortality upon contracting BKD (Hay 2003, Jonas et al. 2002, Nuhfer et al. 2005, Starliper et al. 1997). However, strains of the bacterium isolated from Lake Michigan have been found to be more virulent than those from the Pacific Northwest (Austin and Austin 1987, Grayson et al. 1999, Jonas et al. 2002, Starliper et al. 1997, Thomas et al. 1999) and in some cases have resulted in higher than anticipated levels of infection (e.g., Nalepa et al. 2005).

While R. salmoninarum affects multiple Great Lakes native species, as of 2006, prevalence and mortalities in infected fish had been relatively low (GLFHC 2006). However, more recent data from 2011 indicates that this bacterium has become more widely distributed with varying prevalence throughout Michigan state hatcheries and wild populations. The bacterium was detected in brook trout at 1.7% to 54% prevalence; Atlantic salmon 1.7% to 50%; muskellunge, lake sturgeon, and channel catfish at 1.7% to 10%; and lake trout, splake, and lake herring at 1.7%-5% prevalence (GLFHC 2012). That same year, R. salmoninarum was detected at low prevalence in Minnesota hatcheries and for the first time in lake trout from Mountain Lake, MN. The Minnesota Department of Natural Resources is considering whether or not to continue using that lake as a brood stock source (GLFHC 2012).

Renibacterium salmoninarum is considered to be endemic in Ontario and is found in OMNR fish culture facilities at low levels (GLFHC 2012).

Symptoms of BKD include abdominal fluid build-up and swelling, pseudomembranes and hemorrhaging on viscera, kidney and gill necrosis, intestinal hemorrhaging, ulcers or abscesses in muscles, protruding eyeballs, anemia, blood blisters, and lesions of the eyes, liver, spleen, and heart (Austin and Austin 1987, Holey et al. 1998). Because of this, infected fish may be more susceptible to predation (Lafferty and Morris 1996). However, cascading food web effects as a result of BKD infection in the Great Lakes have not been reported.

Renibacterium salmoninarum has a high socio-economic impact in the Great Lakes.
Lake whitefish (C. clupeaformis) collected from Lake Michigan and Lake Huron between 2003 and 2006 tested positive for R. salmoninarum at 62.31% prevalence. Lake whitefish have a high commercial value in the Great Lakes (Nalepa et al. 2005), and if as a result of BKD infection, populations were to fluctuate significantly, there could be serious economic effects.

Great Lakes non-native species that have tested positive for R. salmoninarum include Chinook salmon (Oncorhynchus tshawytscha) (Holey et al. 1998), coho salmon (O. kisutch), and rainbow trout (O. mykiss) (Jonas et al. 2002). Rainbow trout (O. mykiss) is less susceptible to BKD infection and may not experience mortality upon contracting the disease, whereas coho salmon (O. kisutch) and Chinook salmon (O. tshawytscha) are more susceptible to infection and more prone to mortality (Hay 2003, Jonas et al. 2002, Nuhfer et al. 2005, Starliper et al. 1997).

Prevalence rates of R. salmoninarum were up to 100% in some parts of the Lake Michigan drainage around 1986. This outbreak of BKD caused heavy mortality in Chinook salmon in 1988 and persisted in the population until 1992. That year, boat fisheries observed at least a 40% decline in Chinook salmon catch per unit effort levels. By 1993, catch per unit effort was 15% of the peak observed in 1986 (Holey et al. 1998). In 1986, the Strawberry Creek spawning weirs in Wisconsin documented no presence of R. salmoninarum. In 1988, the bacterium was isolated in 67% of the returning Chinook salmon and then persisted at moderate levels through 1992 (Holey et al. 1998). The 1980s’ mortality events are believed to have also been influenced by increased vulnerability due to food shortages, particularly alewives (Alosa pseudoharengus), high Chinook salmon density, and high parasite loads (Holey et al. 1998). While significant for the fisheries at that time, given the magnitude of the stocks present in Lake Michigan, it is improbable that the Chinook salmon die-offs observed in the late 1980s and early 1990s caused a residual demographic bottleneck in those populations (Weeder et al. 2005).

As of 2006, the overall prevalence of R. salmoninarum in non-native Great Lakes species was thought to be low and declining over time (GLFHC 2006, Jonas et al. 2002). However in 2011, R. salmoninarum was widely distributed with varying prevalence throughout Michigan state hatcheries and wild populations. The bacterium was detected in brown trout (Salmo trutta) at 1.7% to 54% prevalence, rainbow trout at 1.7% to 40%, coho salmon at 1.7% to 10%, and Chinook salmon at 1.7% to 5% prevalence (GFLHC 2012).

Renibacterium salmoninarum was detected in 11 of 12 production lots of rainbow trout and coho salmon from 4 of 5 Indiana state hatcheries with prevalence ranging from 1.67% to 26.67%, with six cases exceeding 10% (GLFHC 2012).

Bloater (C. hoyi) is a staple of Great Lakes native and non-native salmonid diets. Reductions in salmonid populations and economic effects to the Great Lakes fishing industry could be realized if bloater populations decline (Wyns 2002).

There is little or no evidence to support that Renibacterium salmoninarum has significant beneficial effects in the Great Lakes.
In addition to commercially valuable non-native Great Lakes species (see Socio-economic Impacts), sea lamprey (Petromyzon marinus) has tested positive for BKD (Eissa et al. 2006). However, infection is not likely to control sea lamprey populations.


Regulations: (pertaining to the Great Lakes)
Ohio requires source facilities outside the Great Lakes basin to document annual health inspections showing no BKD occurrences for the previous five years prior to importing salmonids to the Lake Erie watershed (Baird 2005). Indiana requires source facilities outside the basin to document they are BKD free prior to importing salmonid stock. Asymptomatic salmonids found carrying the pathogen can be sold in-state if source facilities are within the Great Lakes basin (Baird 2005). Michigan, Illinois, Wisconsin, and Minnesota also require imported salmonid health inspections (NCRAC 2010). Minnesota allows the importation of infected eggs, if prior egg treatments have been approved (Baird 2005).
New York, Pennsylvania, Ohio, Michigan, Indiana, Illinois, Wisconsin, and Minnesota have instated similar baitfish regulations to control the spread of BKD and other fish pathogens. Those of New York include that bait harvested from inland waters for personal use is only permitted to be used within the same body of water from which it was taken and cannot be transported overland (with the exception of smelt, suckers, alewives, and blueback herring). Once transported, baitfish cannot be replaced to its original body of water (NYSDEC 2012).

Live or frozen bait harvested from inland New York waters for commercial purposes is only permitted to be sold or possessed on the same body of water from which it was taken and cannot be transported over land unless under a permit and or accompanied by a fish health certification report. Bait that is preserved and packaged by any method other than freezing, such as salting, can be sold and used wherever the use of bait fish is legal as long as the package is labeled with the name of the packager-processor, the name of the fish species, the quantity of fish packaged, and the means of preservation (NYSDEC 2012).

Certified bait may be sold for retail and transported overland as long as the consumer maintains a copy of a sales receipt that contains the name of the selling vendor, date sold, species of fish sold, and quantity of fish sold. Bait that has not been certified may still be sold but the consumer must maintain a sales receipt containing the body of water where the bait fish was collected and a warning that the bait cannot be transported by motor vehicle. Bait sold for resale require a fish health certification along with a receipt that contains the name of the selling vendor, date sold, species of fish sold, and quantity of fish sold, which must be kept for 30 days or until all bait is sold (NYSDEC 2012).

In addition to baitfish protections, prior to placing fish in New York waters, a fish health certification report must document that the fish are BKD free.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

There are no known biological control methods for this species.

Culling infected stock has reduced the prevalence of R. salmoninarum in aquaculture (Gudmundsdóttir et al. 2000, Maule et al. 1996, Pascho et al. 1991).

Antimicrobial agents used to treat R. salmoninarum include nitrofurans, bacitracin, chlortetracycline, oxytetracycline, novobiocin (Wolf and Dunbar 1959), cephalosporins, gentamicin, clindamycin, lincomycin, oleandomycin, kitasamycin, spiramycin, penicillin (Austin 1985), cefazolin, tiamulin (Bandín et al. 1991), cephradine, rifampicin, (Brown et al. 1990), tetracycline (Austin 1985, Bandín et al. 1991), chloramphenicol (Austin 1985, Wolf and Dunbar 1959), and erythromycin (Austin 1985, Bandín et al. 1991, Lee and Evelyn 1994, Wolf and Dunbar 1959).

Erythromycin-enhanced feed administered at 100 mg/kg/day for 21 days (Wolf & Dunbar 1959) or for 10 days (Austin 1985) is believed to be the most effective treatment for bacterial kidney disease (Hirvela-koski 2005).  Erythromycin phosphate is an effective chemoprophylaxis in pre-spawning adult brood fish. Subcutaneous injections of 11 mg/kg (Hirvela-koski 2005) or 20 mg/kg (Gudmundsdóttir et al. 2000, Pascho et al. 1991) administered to fish entering trapping facilities and at 21-30 day intervals thereafter (Hirvela-Koski 2005) has reduced mortality in re-spawning Pacific salmon by 10-50% (Groman and Klonz 1983). However, this treatment does not effectively destroy the pathogen from all eggs (Brown et al. 1990). A study by Lee and Evelyn (1994) showed female coho salmon treated with 20 mg/kg erythromycin prior to spawning yielded no vertical transmission of BKD. Treatment success relies on careful timing of the injections in adult salmonids before spawning (Elliott et al. 1989).

Disinfecting eggs with 100 mg/L of iodine for 15 minutes may not eliminate vertical transmission, but can reduce the severity of the disease (Bullock et al. 1978). Treating eggs with iodine at 250 or 500 mg/L for 15-120 minutes is effective at eliminating R. salmoninarum. However, after treatment, variable numbers of R. salmoninarum cells have survived. This is due to cells within the cell aggregates never coming in contact with the iodine (Evelyn et al. 1984, 1986). Renibacterium salmoninarum is inactivated by free chlorine (≤0.05 mg/L), which can be used as a disinfectant and to treat intake and effluent (Pascho et al. 1995).

Prevention is the preferred control method of BKD in cultured stocks (OIE 2003).

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

Remarks: Renibacterium salmoninarum was originally known as Corynebacterium salmoninus.Additional common names include: corynebacterial kidney disease, salmonid kidney disease

References (click for full reference list)

Other Resources:
Author: Kipp, R.M., A.K.Bogdanoff, and A. Fusaro.

Contributing Agencies:

Revision Date: 5/23/2018

Citation for this information:
Kipp, R.M., A.K.Bogdanoff, and A. Fusaro., 2024, Renibacterium (Corynebacterium) salmoninarum Sanders and Fryer, 1980: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 5/23/2018, Access Date: 4/23/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.