Mucus of salmonids was evaluated as a source for nonlethal detection of the pathogen Aeromonas salmonicida in fish. The bacterium was readily isolated from mucus on dilution plates when Coomassie Brilliant Blue agar was the primary plating medium. Kidney samples from the fish that served as sources of mucus were similarly processed. Infection was detected in 56% of mucus samples from lake trout Salvelinus namaycush that were undergoing an epizootic of furunculosis, but only 6% of the kidneys from these fish were positive for the pathogen. Only 1% of asymptomatic brown trout Salmo trutta sampled at another fish hatchery had A. salmonicida in their mucus, and none had a kidney infection. Combined results from the examination of two pools of Atlantic salmon Salmo salar reared at a third hatchery indicated that 37% of these fish had mucus infections caused by A. salmonicida , but only 4% of the kidneys were infected.

Journal of Aquatic Animal Health↗

USGS1991

Isolation and phenotypic characterization of an oxidase-negative Aeromonas salmonicida causing furunculosis in coho salmon (Oncorhynchus kisutch)

An oxidase-negative Aeromonas salmonicida was isolated from coho salmon ( Oncorhynchus kisutch ) suffering from an epizootic of furunculosis at the state hatchery near Belfair, Washington. Typical, oxidase-positive A. salmonicida was isolated concurrently from the same population of fish. Mortality was controlled with medicated feed treatments. Evidence supporting the identification of the two types of A. salmonicida is presented. Methods for the proper identification of oxidase-negative A. salmonicida isolates are evaluated.

Journal of Wildlife Diseases↗

USGS1990

Serological investigation of the fish pathogen Edwardsiella ictaluri, cause of enteric septicemia of catfish

The serological relationships among 32 isolates of Edwardsiella ictaluri obtained from fish were studied. The strains were extremely homogeneous in protein and lipopolysaccharide preparations as observed by sodium-dodecyl-sulfate polyacrylamide gel electrophoresis. Only minor variations were observed in the structural O-side chain subunits in three isolates; however, such variation did not preclude antigenic recognition by two E. ictaluri antisera in either microagglutination or Western blot immunoassays. The antigenic homogeneity of E. ictaluri was further demonstrated by microagglutination assays with both formalin-killed and heat inactivated cellular antigens. The minimal degree of antigenic variability observed suggested that most isolates of E. ictaluri compose a single antigenic serotype.

Journal of Wildlife Diseases↗

USGS1990

Aeromonas hydrophila infections of fishes

No abstract available at this time

Fish Health Bulletin↗

USGS1990

Enteric redmouth disease of salmonids

No abstract available at this time

Fish Disease Leaflet↗

USGS1988

Book Review: Bacterial fish pathogens: Disease in farmed and wild fish

No abstract available.

Fisheries↗

USGS1987

Immunization of salmonids against Yersinia ruckeri: Significance of humoral immunity and cross protection between serotypes

Brook trout ( Salvelinus fontinalis ) were immunized with bacterins containing either Serotype 1 or 2 isolates of Yersinia ruckeri to determine the relative degree of cross-protection afforded when the fish were challenged with the homologous or heterologous serotype. While fish immunized with pH-lysed bacterins produced highly specific agglutinins that did not cross-react with antigens derived from a heterologous serotype of Y. ruckeri all fish were protected against experimental challenge, regardless of which serotype was used for bacterin production and experimental challenge. Other experiments indicated that brook trout injected intraperitoneally with highly specific antibodies could not be passively immunized against experimental challenge.

Journal of Wildlife Diseases↗

USGS1986

Susceptibility of salmonids to furunculosis: Differences between serum and mucus responses against Aeromonas salmonicida

At the Reeds Creek (West Virginia) state hatchery, mortality from enzootic furunculosis is most severe among brown trout Salmo trutta, intermediate in brook trout Salvelinus fontinalis, and virtually nonexistent in rainbow trout Salmo gairdneri. In each species, survivors of epizootics had developed similar levels of protective antibodies in their sera as demonstrated by microtiter agglutination and passive immunization experiments. We concluded that serum antibodies were not related to graded differences in resistance to furunculosis. These same fishes, however, produced a mucus precipitin that reacted with cell‐free bacterial extracts in single‐radial immunodiffusion assays. The mucus precipitin activity correlated with the resistance of the three species to furunculosis. Breeding studies with brown trout also showed that fish selected for a high level of mucus precipitin activity against Aeromonas salmonicida, the cause of fish furunculosis, produced progeny that were more resistant to furunculosis than other progeny produced from random matings. The nonspecificity of the mucus precipitin reaction was also confirmed by reactions with cell‐free extracts from Vibrio anguillarum and Aeromonas hydrophila.

West Virginia↗