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Columnaris Disease of Fishes University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln US Fish & Wildlife Publications US Fish & Wildlife Service 1986 COLUMNARIS DISEASE OF FISHES G. L. Bullock u.s. Fish and Wildlife Service T. C. Hsu University of Georgia E. B. Shotts Jr. University of Georgia Follow this and additional works at: https://digitalcommons.unl.edu/usfwspubs Part of the Aquaculture and Fisheries Commons Bullock, G. L.; Hsu, T. C.; and Shotts, E. B. Jr., "COLUMNARIS DISEASE OF FISHES" (1986). US Fish & Wildlife Publications. 129. https://digitalcommons.unl.edu/usfwspubs/129 This Article is brought to you for free and open access by the US Fish & Wildlife Service at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in US Fish & Wildlife Publications by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. COLUMNARIS DISEASE OF FISHESl G. L. Bullock u.s. Fish and Wildlife Service National Fisheries Center-Leetown National Fish Health Research Laboratory Box 700, Kearneysville, West Virginia 25430 T. C. Hsu and E. B. Shotts. Jr. Department of Medical Microbiology College of Veterinary Medicine University of Georgia Athens, Georgia 30602 FISH DISEASE LEAFLET 72 UNITED STATES DEPARTMENT OF THE INTERIOR Fish and Wildlife Service Division of Fisheries and Wetlands Research Washington, D.C. 20240 1986 lR " eVISlOn of Fish Disease Leaflet 45 (1976), same title. by S. F. Snieszko and G. L. Bullock. Introduction bacteria penetrate the dermis and cause necrosis of muscle fibers and destruction of capillaries. Both in Pacific salmonids and in warmwater Columnaris disease is an acute to chronic bac­ pondfishes, columnaris commonly causes exten­ terial infection that affects anadromous salmonids sive gill necrosis, which starts at the margins of and virtually all species of warmwater fishes. the filaments and progresses inward toward the Davis (1922), who first described the disease, arches. Characteristic pathology associated with named it columnaris because the causal bacterial the gill lesions includes marked congestion of cells seen in wet mounts of affected gills and fins blood vessels, dissociation of surface epithelium were arranged in columnar aggregations. Ordal of lamellae, and scattered hemorrhages. and Rucker (1944) were the first to isolate the As gill and muscle tissues are destroyed, the bac­ causal organism and, based on cellular morphol­ teria become systemic but internal pathology is ogy, identified it as a myxobacterium. Organisms limited to glomerular lesions. Cells of Flexibacter classified in the order Myxobacterales are long, usually cannot be seen in stained smears, but the thin gram-negative rods that are motile on agar organisms can be readily cultured. media by a creeping or flexing motion. They have a life cycle composed of vegetative cells, microcysts (resting cells), and fruiting bodies, or only vegetative cells and microcysts. Ordal and Etiology and Diagnosis Rucker (1944) reported that the myxobacterium from columnaris disease produced both fruiting Flexibacter columnaris has been extensively bodies and microcysts and named the organism studied and is the best known of the flexibacters Chondrococcus columnaris. Garnjobst (1945) pathogenic to fish. When grown on the medium studied strains of the columnaris bacterium and described by Anacker and Ordal (1955) the reported that microcysts were present but not bacterium forms pale yellow colonies that have a fruiting bodies. Because fruiting bodies could not convoluted center, rhizoid edges, and tend to be demonstrated, she placed the organism in the adhere to the medium. This type of colony has not genus Cytophaga and suggested Cytophaga been encountered in other flexibacters pathogenic columnaris. However, in the eighth edition of to fish (Bullock 1972). The finding by Pyle and Bergey's Manual of Determinative Bacteriology Shotts (1981) that F. columnaris showed little (Buchanan and Gibbons 1974), it was stated that DNA binding with other flexibacters from the columnaris bacterium produced neither fruit­ diseased fish indicated that F. columnaris is not ing bodies nor microcysts. Therefore it was closely related to the other flexibacteria. removed from the Myxobacterales, placed in the A selective medium (Fig. 1) for the isolation of order Cytophagales, and renamed Flexibacter F. columnaris has been developed (T. C. Hsu and columnaris. E. B. Shotts, unpublished data) that is easier to work with in clinical situations than is the Anacker and Ordal medium (Fig. 1). It is composed of 2 g Clinical Signs and Pathology tryptone, 0.5 g yeast extract, 3 g gelatin, 15 g agar, and 1,000 mL deionized water. It is autoclaved at Columnaris disease begins externally on body 15 psi for 15 min and cooled to 45°C; filter decon­ surfaces and gills, and the lesions tend to vary taminated neomycin sulfate (4.0 /Lg/mL) is added with the fish. In scaleless fish such as the catfishes and the medium is poured into petri dishes. (Ictalurus sp.), initial lesions are small and circu­ Presumptive diagnosis of columnaris disease is lar and have gray-blue necrotic centers and red based on the presence of typical lesions containing margins surrounded by a ring of inflamed skin. As long, thin gram-negative rods, and the formation the disease progresses, the lesions spread and may of characteristic columns in infected tissues. Cover most of the body. In scaled fish such as the The appearance of the characteristic yellow, bluegill (Lepomis macrochirus), necrotic lesions spreading colonies within 48 h on the Hsu-Shotts begin at the outer margins of the fins and spread or Anacker and Ordal (1955) medium, and a posi­ inward toward the body. In advanced body lesions, tive slide agglutination test with F. columnaris 1 2 Virulence Factors Pacha and Ordal (1962) determined the virulence of 500 strains of F. columnaris, using a bath exposure and 6- to 14-month-old sockeye salmon (Oncorhynchus nerka) Or chinook salmon (0. tshawytscha). Test fish were held for 2 min in a 1:20 dilution of a 24-h broth culture and were then transferred to flowing water at 18°C. Strains were designated as of high virulence if all exposed salmon died within 24 h, of moderate virulence if all salmon died within 48 h, of intermediate virulence if all salmon died within 96 h, and of low virulence if mOre than 96 h was required for all salmon to die. However, virulence among strains was neither stable nOr uniform. For example, Pacha (1961) found that none of the 12 single­ colony isolates from a high virulence strain were still virulent when salmon were challenged. The factors that contribute to this reduction Or loss of virulence of F. columnaris strains are still being investigated. Morita (1975) reported that flexibac­ ters from fish develop powerful proteolytic enzymes that lyse intact bacterial cells. Also, virulence may be reduced by the inactivation of certain enzymes that normally break down the integument and allow the spread of the bacteria­ e.g., hyaluronidase (B. R. Griffin, U.S. Fish and Wildlife Service, Fish Farming Experimental Station, personal communication) and chondroitin sulfatase (E. B. Shotts, unpublished data). Source and Reservoir of Infection Although F. columnaris can survive in sterile water Or mud, survival principally depends on temperature, water hardness, pH, and other Fig. 1. Isolation of Flexibacter columnaris from infected tissue. Upper photo-Tissue streaked onto Cytophaga factors. Becker and Fujihara (1978) reported that agar, which does not allow isolation of F. columnaris when F. columnaris cells were seeded in sterile because it is overgrown by other bacteria. Lower mud for 77h, 62% survived at lOoC, but only 35% photo-Tissue streaked onto Hsr;-Shotts selective at 20°C. Fijan (1968) reported that low pH, soft medium, which suppresses growth of most contaminating bacteria but allows growth of the water, and low organic content decreased survival characteristic spreading, rhizoid colonies of of F. columnaris. However, fish serve as the F. columnaris. primary reservoir, and coarse fish such as suckers (Catostomidae) serve as reservoirs of infection for Pacific salmon. Bacteria are shed from lesions Or antiserum, constitute a confirmatory diagnosis. A from gills-only once by some fish, but several direct Or indirect fluorescent antibody test can also times by others. High temperatures and densities be used to identify F. columnaris (Amend 1983). favor increased release of bacteria. 3 Transmission salmon led to the speculation that the operation of a plutonium plant complex at Hanford, Washington, was a contributing factor. However, Columnaris disease is principally transmitted studies conducted from 1965 to 1976 showed that from fish to fish, but many factors influence the the increased incidence and severity of the disease release of cells. Holt et al. (1975) found that when was caused by environmental modifications steelhead trout (Salmo gairdneri) or coho salmon associated with hydroelectric development. Over (0. kisutch) experimentally infected with colum­ a period of 30 years the Columbia River was trans­ naris were held in water at 12 to 20°C, mortality formed from a free-flowing stream to a series of increased with temperature. The disease was impoundments. The resultant increased tempera­ reported to be intensified by low dissolved oxygen ture, reduced flow velocity, and higher fish densi­ and elevated ammonia by Chen et al. (1982), and ties favored the proliferation of columnaris (Becker by the addition of an organic material such as for­ and Fujihara 1978). mulated feed (in Japanese eels, Anguilla japonica) Davis (1922, 1953) reported that after fish had by Sugimoto et al. (1981). been handled, the development or intensification of columnaris could be prevented by treating them with a 20-min copper sulfate bath at 37 ppm Host and Geographic Range (1:30,000) or by adding copper sulfate to pond water at 0.5 ppm; he also recommended a dip of Columnaris disease is common in fresh and 1 to 2 min in a dilution of 1:2,000.
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