Bacterial cold water disease
Encyclopedia
Flavobacterium psychrophilum (previously known as Cytophaga psychrophila
) is a member of the Flavobacteriaceae
family. It is a gram-negative
rod-shaped bacterial pathogen that can cause bacterial cold water disease (BCWD) in salmonid fish. The disease typically occurs at temperatures below 13⁰C, and disease can be seen in any area with water temperature consistently below 15⁰C. Although salmon is the most commonly affected species, most fish are susceptible to infection. This disease is not zoonotic.
Asymptomatic carrier fish and contaminated water provide reservoirs for disease. Transmission is mainly horizontal
, but vertical transmission
can also occur.
BCWD may be referred to by a number of other names including cold water disease, peduncle disease, fit rot, tail rot and rainbow trout fry mortality syndrome.
. Fins may appear dark, torn, split, ragged, frayed and may even be lost completely. Affected fish are often lethargic and stop feeding. Infection may spread systemically. Salmonid fish can also get a chronic form of BCWD following recovery from typical BCWD. It is characterised by erratic “corkscrew” swimming, blackened tails and spinal deformities.
In Rainbow Trout Fry Syndrome, acute disease with high mortality rates occurs. Infected fish may show signs of lethargy, inappetance and exopthalmos before death.
A presumptive diagnosis can be made based on the history, clinical signs, pattern of mortality and water temperature, especially if there is a history of the disease in the area. The organism can be cultured for definitive diagnosis. Alternatively, histology should show periostitis
, osteitis
, meningitis
and ganglioneuritis.
and broodstock.
To prevent the disease, its is necessary to ensure water is pathogen-free and that water hardening is completed effectively for eggs.
Cytophaga
Cytophaga is a genus of Gram-negative, gliding, rod-shaped bacteria.-Species:The following are some species in Cytophaga:* Cytophaga columnaris — the cause of columnaris disease in salmonid fish, as associated with increased water temperature; it is characterized by white necrotic plaques...
) is a member of the Flavobacteriaceae
Flavobacteriaceae
The family Flavobacteriaceae is composed of environmental bacteria. Most species are aerobic, some are microaerobic to anaerobic, for example Ornithobacterium, Capnocytophaga and Coenonia....
family. It is a gram-negative
Gram-negative
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...
rod-shaped bacterial pathogen that can cause bacterial cold water disease (BCWD) in salmonid fish. The disease typically occurs at temperatures below 13⁰C, and disease can be seen in any area with water temperature consistently below 15⁰C. Although salmon is the most commonly affected species, most fish are susceptible to infection. This disease is not zoonotic.
Asymptomatic carrier fish and contaminated water provide reservoirs for disease. Transmission is mainly horizontal
Horizontal transmission
Horizontal transmission is the transmission of a bacterial, fungal, or viral infection between members of the same species that are not in a parent-child relationship....
, but vertical transmission
Vertical transmission
Vertical transmission, also known as mother-to-child transmission, is the transmission of an infection or other disease from mother to child immediately before and after birth during the perinatal period. A pathogen's transmissibility refers to its capacity for vertical transmission...
can also occur.
BCWD may be referred to by a number of other names including cold water disease, peduncle disease, fit rot, tail rot and rainbow trout fry mortality syndrome.
Clinical Signs & Diagnosis
Fish infected with typical BCWD have lesions on the skin and finsFINS
FINS is a network protocol used by Omron PLCs, over different physical networks like Ethernet, Controller Link, DeviceNet and RS-232C....
. Fins may appear dark, torn, split, ragged, frayed and may even be lost completely. Affected fish are often lethargic and stop feeding. Infection may spread systemically. Salmonid fish can also get a chronic form of BCWD following recovery from typical BCWD. It is characterised by erratic “corkscrew” swimming, blackened tails and spinal deformities.
In Rainbow Trout Fry Syndrome, acute disease with high mortality rates occurs. Infected fish may show signs of lethargy, inappetance and exopthalmos before death.
A presumptive diagnosis can be made based on the history, clinical signs, pattern of mortality and water temperature, especially if there is a history of the disease in the area. The organism can be cultured for definitive diagnosis. Alternatively, histology should show periostitis
Periostitis
Periostitis, also known as periostalgia, is a medical condition caused by inflammation of the periosteum, a layer of connective tissue that surrounds bone...
, osteitis
Osteitis
Osteitis is a general term for inflammation of bone. More specifically, it can refer to one of the following conditions:* Alveolar osteitis or "dry socket"* Condensing osteitis * Osteitis deformans...
, meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
and ganglioneuritis.
Treatment & Control
Quaternary ammonium compounds can be to the water of infected adult fish and fry. Alternatively, the antibiotic 'teramycin' can be given to adults, frySpawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
and broodstock.
To prevent the disease, its is necessary to ensure water is pathogen-free and that water hardening is completed effectively for eggs.