Columnaris (also referred to as cottonmouth) is a symptom of

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

fish Fish are aquatic, craniate, gill-bearing 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. Approximately 95% of li ...

which results from an

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

caused by the

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

, aerobic, rod-shaped

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

Flavobacterium columnare ''Flavobacterium columnare'' is a thin Gram-negative rod bacterium of the genus '' Flavobacterium''. The name derives from the way in which the organism grows in rhizoid columnar formations. The species was first described by Davis (1922), and t ...

''. It was previously known as ''Bacillus columnaris, Chondrococcus columnaris, Cytophaga columnaris'' and ''Flexibacter columnaris''. The bacteria are ubiquitous in fresh water, and cultured fish reared in ponds or raceways are the primary concern – with disease most prevalent in air temperatures above 12–14 °C. It is often mistaken for a fungal infection. The disease is highly contagious and the outcome is often fatal. It is not

zoonotic A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a bacterium, virus, parasite or prion) that has jumped from a non-human (usually a vertebrate) to a human. ...

Causes

The bacteria usually enter fish through gills, mouth, or small wounds, and is prevalent where high bioloads exist, or where conditions may be stressful due to overcrowding or low dissolved oxygen levels in the water column. The bacteria can persist in water for up to 32 days when the hardness is 50 ppm or more. Minerals are however essential for fish and often the reduction or removal of such minerals in treatment for Columnaris would affect fish mineral uptake and thus affect: oxygen utilization, osmotic regulation, metabolic processes, among may other biological processes and poor minerals (GH) may be a contributing cause to the advancement in severity of this disease, as deficits can increase vulnerability to opportunistic infections (citations).

Symptoms

An infection will usually first manifest in fish by causing frayed and ragged fins. This is followed by the appearance of ulcerations on the skin, and subsequent epidermal loss, identifiable as white or cloudy, fungus-like patches – particularly on the gill filaments. Mucus often also accumulates on the gills, head and dorsal regions. Gills will change colour, either becoming light or dark brown, and may also manifest necrosis. Fish will breathe rapidly and laboriously as a sign of gill damage. Anorexia and lethargy are common, as are mortalities, especially in young fish.

Diagnosis

Bacteria can be isolated from gills, skin and the kidneys. For definitive diagnosis, the pathogen should then be cultured on reduced nutrient agar. Inhibiting contaminant growth on the agar by adding antibiotics and keeping the temperature at 37 °C should improve culture results. Colonies are small, 3–4 mm in diameter, and grow within 24 hours. They are characteristically rhizoid in structure and pale yellow in colour.

Prognosis

Ulcerations develop within 24 to 48 hours. Fatality occurs between 48 and 72 hours if no treatment is pursued; however, at higher temperatures death may occur within hours. Other symptoms may accompany the disease, including lethargy, color loss, redness around the infection site, loss of appetite and twitching or rubbing the body against objects.

Treatment

As ''Flavobacterium columnare'' is

, fish can be treated with a combination of the antibiotics

nitrofurazone Nitrofurazone (INN, trade name Furacin) is an antimicrobial organic compound belonging to the nitrofuran class. It is most commonly used as a topical antibiotic ointment. It is effective against gram-positive bacteria, gram-negative bacteria, ...

and

kanamycin Kanamycin A, often referred to simply as kanamycin, is an antibiotic used to treat severe bacterial infections and tuberculosis. It is not a first line treatment. It is used by mouth, injection into a vein, or injection into a muscle. Kanamycin ...

administered together synergistically. A medicated fish bath (ideally using aquarium

merbromin Merbromin (marketed as Mercurochrome, Merbromine, Mercurocol, Sodium mercurescein, Asceptichrome, Supercrome, Brocasept and Cinfacromin) is an organomercuric disodium salt compound used as a topical antiseptic for minor cuts and scrapes and a ...

, alternately

methylene blue Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication. Methylene blue is a thiazine dye. As a medication, it is mainly used to treat methemoglobinemia by converting the ferric iron in hemoglobin ...

, or

potassium permanganate Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, that dissolves in water as K+ and , an intensely pink to purple solution. Potassium permanganate is widely used in the c ...

and salt), is generally a first step, as well lowering the aquarium temperature to 75 °F (24 °C) is a must, since columnaris is much more virulent at higher temperatures, especially 85–90 °F. Medicated food containing

oxytetracycline Oxytetracycline is a broad-spectrum tetracycline antibiotic, the second of the group to be discovered. Oxytetracycline works by interfering with the ability of bacteria to produce essential proteins. Without these proteins, the bacteria cannot g ...

is also an effective treatment for internal infections, but resistance is emerging. Potassium permanganate,

copper sulfate Copper sulfate may refer to: * Copper(II) sulfate, CuSO4, a common compound used as a fungicide and herbicide * Copper(I) sulfate Copper(I) sulfate, also known as cuprous sulfate, is an inorganic compound with the chemical formula Cu2 SO4. It ...

, and

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%� ...

can also be applied externally to adult fish and fry, but can be toxic at high concentrations. Vaccines can also be given in the face of an outbreak or to prevent disease occurrence.

References

External links

* Columnaris Disease, expert reviewed and published by Wikivet at http://en.wikivet.net/Columnaris_Disease, accessed 31/08/2011.
Columnaris disease
{{fish disease topics Bacterial diseases of fish