Enteric redmouth disease

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Enteric redmouth disease, or simply redmouth disease is a bacterial infection of freshwater and marine fish caused by the pathogen Yersinia ruckeri . It is primarily found in rainbow trout (Oncorhynchus mykiss) and other cultured salmonids. The disease is characterized by subcutaneous hemorrhaging of the mouth, fins, and eyes. It is most commonly seen in fish farms with poor water quality. Redmouth disease was first discovered in Idaho rainbow trout in the 1950s. [1] The disease does not infect humans. [1]

Fish vertebrate animal that lives in water and (typically) has gills

Fish are gill-bearing aquatic craniate animals that lack limbs with digits. They form a sister group to the tunicates, together forming the olfactores. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Tetrapods emerged within lobe-finned fishes, so cladistically they are fish as well. However, traditionally fish are rendered paraphyletic by excluding the tetrapods. Because in this manner the term "fish" is defined negatively as a paraphyletic group, it is not considered a formal taxonomic grouping in systematic biology, unless it is used in the cladistic sense, including tetrapods. The traditional term pisces is considered a typological, but not a phylogenetic classification.

Yersinia ruckeri is a species of Gram-negative bacteria, known for causing enteric redmouth disease in some species of fish. Strain 2396-61 is its type strain.

Rainbow trout species of trout

The rainbow trout is a trout and species of salmonid native to cold-water tributaries of the Pacific Ocean in Asia and North America. The steelhead is an anadromous (sea-run) form of the coastal rainbow trout(O. m. irideus) or Columbia River redband trout (O. m. gairdneri) that usually returns to fresh water to spawn after living two to three years in the ocean. Freshwater forms that have been introduced into the Great Lakes and migrate into tributaries to spawn are also called steelhead.


Distribution of disease

Some fish species serve as vectors for the disease and have subsequently spread the pathogen to other parts of the world. [1] An example is the fathead minnow (Pimephales promelas) which is responsible for the spread of redmouth disease to trout in Europe. [2] Other vectors include the goldfish (Carassius auratus), Atlantic and Pacific salmon (Salmo salar), the emerald shiner (Notropis atherinoides), and farmed whitefish (Coregonus spp.). Infections have also occurred in farmed turbot (Scophthalmus maximus), seabass (Dicentrarchus labrax), and seabream (Sparus auratus). [1] It can now be found in North and South America, Africa, Asia, and Australia, as well as Europe.

Vector (epidemiology) agent that carries and transmits an infectious pathogen into another living organism

In epidemiology, a disease vector is any agent who carries and transmits an infectious pathogen into another living organism; most agents regarded as vectors are organisms, such as intermediate parasites or microbes, but it could be an inanimate medium of infection such as dust particles.

Fathead minnow species of fish

The fathead minnow is a species of temperate freshwater fish belonging to the genus Pimephales of the cyprinid family. The natural geographic range extends throughout much of North America, from central Canada south along the Rockies to Texas, and east to Virginia and the Northeastern United States. This minnow has also been introduced to many other areas via bait bucket releases. Its golden, or xanthic, strain, known as the rosy-red minnow, is a very common feeder fish sold in the United States and Canada. This fish is best known for producing Schreckstoff.

Goldfish freshwater fish, common in aquariums

The goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It is one of the most commonly kept aquarium fish.

Clinical signs and diagnosis

Infection can cause subcutaneous haemorrhage that presents as reddening of the throat, mouth, gill tips, and fins, and eventual erosion of the jaw and palate. Hemorrhaging also occurs on internal organs, and in the later stages of the disease, the abdomen becomes filled with a yellow fluid - giving the fish a "pot-bellied" appearance. The fish often demonstrate abnormal behavior and anorexia. Mortality rates can be high.

Subcutaneous tissue lowermost layer of the integumentary system in vertebrates

The subcutaneous tissue, also called the hypodermis, hypoderm, subcutis, or superficial fascia, is the lowermost layer of the integumentary system in vertebrates. The types of cells found in the hypodermis are fibroblasts, adipose cells, and macrophages. The hypodermis is derived from the mesoderm, but unlike the dermis, it is not derived from the dermatome region of the mesoderm. In arthropods, the hypodermis is an epidermal layer of cells that secretes the chitinous cuticle. The term also refers to a layer of cells lying immediately below the epidermis of plants.


Ascites is the abnormal buildup of fluid in the abdomen. Technically, it is more than 25 mL of fluid in the peritoneal cavity. Symptoms may include increased abdominal size, increased weight, abdominal discomfort, and shortness of breath. Complications can include spontaneous bacterial peritonitis.

A presumptive diagnosis can be made based in the history and clinical signs, but definitive diagnosis requires bacterial culture and serological testing such as ELISA and latex agglutination.

ELISA assay

The enzyme-linked immunosorbent assay (ELISA) is a commonly used analytical biochemistry assay, first described by Engvall and Perlmann in 1972. The assay uses a solid-phase enzyme immunoassay (EIA) to detect the presence of a ligand in a liquid sample using antibodies directed against the protein to be measured. The ELISA has been used as a diagnostic tool in medicine, plant pathology, and biotechnology, as well as a quality control check in various industries.

A latex fixation test, also called a latex agglutination assay or test, is an assay used clinically in the identification and typing of many important microorganisms. These tests use the patient's antigen-antibody immune response. This response occurs when the body detects a pathogen and forms an antibody specific to an identified antigen present on the surface of the pathogen.

Treatment and control

Several antibiotics are available for the treatment of redmouth disease in fish. Vaccines can also be used in the treatment and prevention of disease. Management factors such as maintaining water quality and a low stocking density are essential for disease prevention.

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<i>Ichthyophthirius multifiliis</i> species of protozoan

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Lymphocystis is a common viral disease of freshwater and saltwater fish. The virus that cause this disease belong to the genus Lymphocystivirus of the family Iridoviridae.

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  1. 1 2 3 4 LSC - Fish Disease Leaflet 82 Archived March 11, 2007, at the Wayback Machine .
  2. Froese, Rainer and Pauly, Daniel, eds. (2006). "Pimephales promelas" in FishBase . December 2006 version.

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