Introduction

Enteric redmouth disease, or simply redmouth disease is a bacterial infection of freshwater and marine fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 caused by the pathogen Yersinia ruckeri. It is primarily found in rainbow trout

Rainbow trout

The rainbow trout is a species of salmonid native to tributaries of the Pacific Ocean in Asia and North America. The steelhead is a sea run rainbow trout usually returning to freshwater to spawn after 2 to 3 years at sea. In other words, rainbow trout and steelhead trout are the same species....

 (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

Fish farming

Fish farming is the principal form of aquaculture, while other methods may fall under mariculture. Fish farming involves raising fish commercially in tanks or enclosures, usually for food. A facility that releases young fish into the wild for recreational fishing or to supplement a species'...

 with poor water quality. Redmouth disease was first discovered in Idaho rainbow trout in the 1950s.. The disease does not affect humans.

Distribution of Disease

Some fish species serve as vectors for the disease and have subsequently spread the pathogen to other parts of the world. An example is the fathead minnow

Fathead minnow

The fathead minnow , is a species of temperate freshwater fish belonging to the Pimephales genus 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...

 (Pimephales promelas) which is responsible for the spread of redmouth disease to trout in Europe. Other vectors include the goldfish

Goldfish

The goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish....

 (Carassius auratus), Atlantic and Pacific salmon

Salmon

Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...

 (Salmo salar), the emerald shiner

Emerald shiner

The Emerald Shiner is one of hundreds of small, silvery, slender fish known as shiners. The identifying characteristic of the emerald shiner is the silvery emerald color on its sides...

 (Notropis atherinoides), and farmed whitefish

Freshwater whitefish

The freshwater whitefish are fish of the subfamily Coregoninae in the salmon family Salmonidae. Along with the freshwater whitefish, the Salmonidae includes the freshwater and anadromous trout and salmon species as well as graylings...

 (Coregonus spp.). Infections have also occurred in farmed turbot

Turbot

The turbot is a species of flatfish in the family Scophthalmidae. It is native to marine or brackish waters of the North Atlantic, Baltic Sea and the Mediterranean Sea.-Etymology:...

 (Scophthalmus maximus), seabass

European seabass

The European seabass, Dicentrarchus labrax, also known as Morone labrax, is a primarily ocean-going fish that sometimes enters brackish and fresh waters. It is also known as the sea dace...

 (Dicentrarchus labrax), and seabream (Sparus auratus). It can now be found in North and South America, Africa, Asia and Australia as well as Europe.

Clinical Signs & 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

Ascites

Ascites is a gastroenterological term for an accumulation of fluid in the peritoneal cavity.The medical condition is also known as peritoneal cavity fluid, peritoneal fluid excess, hydroperitoneum or more archaically as abdominal dropsy. Although most commonly due to cirrhosis and severe liver...

 - giving the fish a "pot-bellied" appearance. The fish often demonstrate abnormal behavior and inappetance. Mortality rates can be high.

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

ELISA

Enzyme-linked immunosorbent assay , is a popular format of a "wet-lab" type analytic biochemistry assay that uses one sub-type of heterogeneous, solid-phase enzyme immunoassay to detect the presence of a substance in a liquid sample."Wet lab" analytic biochemistry assays involves detection of an...

 and latex agglutination

Latex fixation test

A latex fixation test is an agglutination technique used to detect antibodies, such as those produced in response to the rubella virus or the rheumatoid factor...

.

Treatment & Control

There are several antibiotics 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.

External links

• Enteric redmouth - The Scottish Government: Marine and Fisheries
• Enteric Redmouth Disease, reviewed and published by WikiVet
  WikiVet
  WikiVet is a wiki of veterinary content, run using the MediaWiki software. The project is a collaborative initiative involving UK veterinary schools with external support...
  
  at http://en.wikivet.net/Enteric_Redmouth_Disease, accessed 08/09/2011.