Bacterial Diseases of Finfishes PDF

BACTERIAL DISEASES OF FINFISHES BACTERIAL DISEASES OF FINFISHES  Bacterial diseases - common in finfishes  Most are opportunistic pathogens  Include:  Anaerobes  Aerobes  Gram-negative  Gram-positive  Clinical signs of bacterial diseases are non- speci...

BACTERIAL DISEASES OF FINFISHES BACTERIAL DISEASES OF FINFISHES  Bacterial diseases - common in finfishes  Most are opportunistic pathogens  Include:  Anaerobes  Aerobes  Gram-negative  Gram-positive  Clinical signs of bacterial diseases are non- specific and include:  lethargy, anorexia (loss of appetite), cutaneous haemorrhages and ulcers, fin rot, ascites (“Dropsy”), exophthalmia, and colour changes.  BACTERIAL DISEASES OF FINFISHES PATHOGEN DISEASE ANAEROBES Clostridium botulinum Botulism Eubacterium sp. Meningitis PATHOGEN DISEASE AEROBES (GRAM-POSITIVE) Coryneform bacteria Corynebacteriosis Lactobacillus Lactobacillosis / pseudokidney disease Mycobacterium Mycobacteriosis / fish tuberculosis Nocardia Nocardiosis Renibacterium salmoninarum Bacterial kidney disease Streptococcus iniae Streptococcosis PATHOGEN DISEASE AEROBES (GRAM-NEGATIVE) Edwardsiella tarda Edwardsiellosis / Edwardsiella septicemia Edwardsiella ictaluri Enteric septicaemia Yersinia ruckeri Enteric redmouth / Salmon blood spot Aeromonas hydrophila Haemorrhagic septicaemia / Motile Aeromonas septicemia Aeromonas salmonicida Furunculosis Aeromonas sp. Fin rot Aeromonas liquifaciens Eye disease PATHOGEN DISEASE Flexibacter Fin rot Myxobacterium Bacterial gill disease Pseudomonas sp. Red spot Pseudomonas sp. Generalized septicemia Pseudomonas sp. Fin rot Pseudomonas flourescens Pseudomonas septicemia Pseudomonas punctata Dropsy Piscirickettsia salmonis Piscirickettsiosis Vibrio alginolyticus Septicemia Vibrio sp. Vibriosis PATHOGEN DISEASE Acinetobacter Acinetobacter disease Pasteurella piscicida Pasteurellosis / Pseudotuberculosis Chlamydia Epitheliocystis Tenacibaculum maritimum Tenacibaculosis Flavobacterium columnare Columnaris disease (Formerly - Flexibacter columnaris) Flavobacterium psychrophilum Bacterial cold water disease (Formerly - Flexibacter (BCWD) psychrophilus) Flavobacterium sp. Flavobacteriosis Flavobacterium branchiophila Bacterial gill disease (Formerly - Flexibacter branchiophila) DISEASES CONSIDERED TO BE BACTERIAL IN ORIGIN Pathogen Disease Bacteria Strawberry disease Aeromonas, Fin and tail rot Pseudomonas, Vibrio MAJOR BACTERIAL PATHOGENS AEROMONAS  Aerobic Gram-negative cocci  A. salmonicida - Furunculosis  A. hydrophila - Motile Aeromonas Septicemia  A. liquefaciens – Eye disease  Significant resistance to both tetracycline and sulfamerazine occur with these bacteria. EDWARDSIELLA  Aerobic Gram-negative cocci  Edwardsiella is an important bacterial pathogen of fish.  E. tarda - Edwardsiellosis  E. ictaluri -Enteric septicemia YERSINIA  Aerobic Gram-negative cocci  Yersinia ruckeri - Enteric Redmouth Disease  An important pathogen of salmonids, but does affect other species as well. MYCOBACTERIUM  Aerobic – acid fast  Mycobacterial infections / Mycobacteriosis caused by:  Mycobacterium marinum  Mycobacterium chelonae  Mycobacterium fortuitum  All freshwater and marine aquarium fish RENIBACTERIUM  Aerobic – Gram-positive rods  Renibacterium salmoninarum - Bacterial kidney disease STREPTOCOCCUS  Aerobic – Gram-positive cocci  Streptococcus infections / Streptococcosis - S. iniae, S. difficilis, S. parauberis, S. milleri, S. shiloi VIBRIO  Aerobic Gram-negative  Vibrio spp. are primarily pathogens of marine fish.  Vibriosis - V. damsela, V. alginolyticus, and V. anquillarium. FLAVOBACTERIUM  Aerobic- Gram-negative rods  Columnaris infection - Flavobacterium columnare (formerly, Flexibacter columnaris)  Bacterial Gill Disease - Flavobacterium branchiophilum  Coldwater Disease / Peduncle disease - Flavobacterium psychrophilium  1. AEROMONAS HYDROPHILA MAS- MOTILE AEROMONAS SEPTICEMIA  A. hydrophila- opportunistic pathogen  Causes Motile Aeromonas Septicemia  Affects all freshwater fishes  Characterized by:  Fatal septicemia  Exophthalmia  Ascites / dropsy  Ulcer formation PATHOGEN  A. hydrophila:  Gram negative  Motile  Non-spore-forming  Aerobe / facultative anaerobe  Different serotypes have been observed from various sources of fish, isolated in different years and places SUSCEPTIBLE SPECIES:  Most cultured and wild fish are susceptible to infection with A.hydrophila such as:  Carp  Channel catfish  Eel  Goldfish  Trout  Tilapia PREDISPOSING / ENVIRONMENTAL FACTORS: 1. high temperature. 2. overcrowding. 3. reduction of oxygen. 4. malnutrition. 5. heavy infestation with parasites. 6. organic pollution. 7. high ammonia and nitrite level. 8. injuries or damage of the skin and gills. 9. rough handling and transportation of fish. These factors play an important role in lowering the resistance of fish body so fish become more susceptible to infection. TRANSMISSION OF THE DISEASE:  Horizontal transmission  It is distributed widely in water and sediments of ponds  can be transmitted by discharge from the intestinal tract and external lesions on the skin.  Parasitic damage and fungal infection of the epidemic may allow the entry and spread of infection among fish  Carriers also play an important role in transmission of the infection. INCUBATION PERIOD:  Depends upon the temperature of the environment  Acute cases may appear with four to ten days after infection CLINICAL SIGNS:  Fatal septicemia  Exophthalmia  Reddening of the skin  Accumulation of the fluid in the abdominal cavity  Dermal ulceration with hemorrhages and inflammation  Both dermis and epidermis are eroded  Severe tail and fin rot MORTALITY  The disease caused about 80% mortality in fish farming especially when the fish held under stress. DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA. TREATMENT AND CONTROL:  Oxytetracycline  Sulfamerazine  Prolonged bath treatments with potassium permanganate / 1-3% NaCl  Control :  Avoiding stress factors is the best method for prophylaxis of the disease.  Good hygiene  Periodic drying of the pond  Disinfection of ponds  Eggs should be disinfected with acriflavine or Betadine  No commercial vaccine has been developed 2. FURUNCULOSIS  Aeromonas salmonicida  Characterized by formation furuncle or boil-like lesions in various tissues of the body  Mostly associated with salmonids, but other fish can be infected  Obligate pathogen (fish to fish transmission) CAUSATIVE AGENT:  Aeromonas salmonicida:  Gram-negative  Short bacilli  Aerobic / also can grow as a facultative anaerobe  Not spore-forming  Non-motile SUSCEPTIBLE SPECIES:  All species of the family salmonidae  Other than the salmonids:  Carp  Catfish  Young fish are more susceptible to the disease than adult fish. INCUBATION PERIOD:  It is dependent on water temperature.  At 20 0C - 4 to 20 days PREDISPOSING / ENVIRONMENTAL FACTORS:  Poor water quality.  Physical damage of the skin or gills.  Presence of ectoparasites and other diseases.  High temperature.  High stock density.  Rough handling. MODE OF TRANSMISSION:  Primarily horizontal  No vertical demonstrated  Horizontal - Contaminated water, carriers, equipment, clothing, surface of aquatic birds  The infection may occur through injuries of the skin  Reservoirs:  Carrier fish CLINICAL SIGNS:  Rapid death of fish, especially young fish  Raised furuncles  Haemorrhages & skin lesions  Darkening of skin  Rapid breathing  Exophthalmia  Lethargy  Soft and liquefied kidney  Enlarged spleen  Pale liver with haemorrhages  Stomach & intestine may contain bloody mucous  Swim bladder is hyperaemic (increase of blood flow)  Fish may die within 2-3 days. FURUNCULOSIS DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA.  TREATMENT:  Sulfamerazine: 150-220 mg/kg fish weight/day for 10-14 days.  Oxytetracycline: 50-75 mg/kg fish weight/day for 10 days.  Furazolidone: 25-100 mg/kg fish weight/day for 10 days.  Oxolinic acid: 10-mg/kg fish weight/day for 10 days CONTROL:  Stress factors must be removed.  Pond drying and disinfection of pond and equipments  Prevent transportation of fish and water movement from infected areas  SPF fish eggs 3. AEROMONAS LIQUIFACIENS POP EYE / EYE DISEASE  Pop Eye itself is not a disease but a symptom of an underlying problem  Fluids build up either behind the eye or in the eye itself  The most common cause:  is an injury to one or both eyes  An infection  or as a result of poor water quality conditions  Bacterial eye disease – Aeromonas liquifaciens  Symptoms: Cornea of eye becomes vascularised and later becomes opaque; eye ball gets decayed. TREATMENTS:  Separate the affected fish if possible or treat the entire tank  Check the water quality parameters  30% to 50% water exchange  Treat with an anti bacterial agent such as Furan 2  Chloromycetin (8-10 mg/litre) bath for 1 hour for 2-3 days. 4. EDWARDSIELLOSIS  Bacterial disease of a variety of fish species  Caused by Edwardsiella spp.  Characterized by septicaemia and abscess formation. PATHOGEN  The genus Edwardsiella  Includes two species of bacteria  Edwardsiella tarda infects fish and other animals  E. ictaluri infects fish only  A member of the Enterobacteriaceae  Small & straight rods  Gram negative  Motile and facultatively aerobes / anaerobic.  Non-spore-forming  Non-capsulated  The optimum growth temperature range form 26 to 30 0C SUSCEPTIBLE SPECIES  Infects a wide variety of fish  At least 21 species of fish are known to have been infected and probably all species of fish are susceptible under certain conditions  The most predominant hosts are eel and catfish  E. tarda infections are not limited to fish  Often exist as part of the normal intestinal microflora especially in fish eating birds, reptiles, cattle and swine.  Warm-blooded animals including humans have been known to be susceptible to E. tarda.  STRESS FACTORS 1. Fluctuating and high temperature of the water. 2. Low dissolved oxygen. 3. High organic content. 4. Overstocking. 5. High ammonia in water. 6. Rough handling of fish. 7. Improper diet. TRANSMISSION  Horizontal - The mode of transmission may occur from fish to other fish via the water by organisms shed with the faeces.  Cannibalism of infected fish.  Feeding of dead or infected carcasses.  Carriers & Vectors:  Birds help in spreading of infection by picking up dead fish from one pond and flying to another pond and dropping the infected carcasses to healthy one.  Aquatic invertebrates  Human beings  Contaminated nets and equipment can transfer the disease from pond to another.  The micro-organism found normal in the intestinal tract and when fishes put under any stress condition the bacterium have ability to invade the fish and causes the infection. SYMPTOMS  Sudden decrease in feeding  Unusual swimming patterns - spiralling and surfing. Sometimes hang in the water column with head up and tail down.  Hole in head- Open lesions found on the head of diseased fish - usually found in fingerling catfish and not seen in older one.  Ascites.  Exophthalmia.  Pale colouration of skin and gills.  Hemorrhages – at the base of fins, around the head, operculum and abdomen.  Spleen, kidney, liver may be soft, pale in color and have bloody spots.  The intestine is often filled with a bloody fluid.  Small white nodules may be observed in the gills, kidney, liver and spleen. These nodules are packed with bacteria. DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA. 5. ENTERIC SEPTICEMIA OF CATFISH (ESC) EDWARDSIELLA ICTALURI  Very common and devastating bacterial problems in the commercial catfish industry.  Causes:  Pathogen - virulent Edwardsiella ictaluri  Stressed host  Environment - that favors rapid proliferation of the bacteria PATHOGEN  Causative agent - Edwardsiella ictaluri  Gram-negative, rod shaped, weakly motile  Thought to be obligate but can survive in mud for 90 days.  Similar to Edwardsiella tarda SUSCEPTIBLE SPECIES  Channel catfish most susceptible  Trout, salmon and tilapia have been experimentally infected but natural outbreaks have not been reported CLINICAL SIGNS  Changes in swimming behavior:  Spiraling  Star gazing (head up - tail down)  Changes in feeding External Signs  Ulcers  Hole or lightened area on head  Exophthalmia  Swollen belly Internal Signs  Clear - straw colored or bloody fluid in body cavity  Spots in liver  Hemorrhages in muscle  Intestine often filled with bloody fluid EXTERNAL SIGNS ESC “HOLE IN THE HEAD” TRANSMISSION  Horizontal  Enters through – Gills / oral cavity  Transmitted through water  Transmitted by cannibalism  Transmitted by carrier fish, equipment and birds DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA. TREATMENT  Treatment with medicated feeds  Romet 30 and Romet B  Sulfadimethoxine and ormetoprim  Fed at recommended rate for 5 days  Terramycin  Fed at recommended rate for 10-14 days  21 day withdrawal period CONTROL AND PREVENTION  Prevention by reducing stress  Nutritional supplements  Vaccination  Treatment with medicated feeds 6. MYCOBACTERIOSIS  Fish mycobacteriosis  Caused by Mycobacterium spp.  Many fishes - freshwater, brackish water and saltwater fishes.  Characterized by:  Emaciation (weight loss)  inflammation of the skin  exophthalmia  ulceration  greyish nodules in the internal organs. PATHOGEN  Pleomorphic  Acid fast  Non motile  Non-sporulated PATHOGEN  Several species of mycobacterium known to cause mycobacterial disease in fish.  The most common species isolated form fish are:  Mycobacterium marinum isolated from marine fishes.  Mycobacterium fortuitum isolated from freshwater and brackish water fishes.  Mycobacterium cheloni isolated from pacific salmonids.  The optimum growth temperature is 25-35 0C STRESS / PREDISPOSING FACTORS:  Disease outbreaks in cultured fish appear to be related to management factors such as:  The quality & quantity of nutrient and water supplied.  High stocking density.  Poor management of fish farm. SUSCEPTIBLE SPECIES:  Mycobacteriosis - worldwide distribution in fish population.  About 167 species of both freshwater and saltwater fishes have been reported as hosts for this disease.  Reported in freshwater prawn & cod.  in aquarium fish  in natural population INCUBATION PERIOD:  The incubation period varies greatly – weeks / months to years  depends on:  susceptibility of fishes  temperature  severity of exposure. MODE OF TRANSMISSION:  Horizontal:  Fish may be infected by ingesting feed & water contaminated with faecal material, urine or exudates from diseased animals that contain mycobacteria.  The infection may occur through the skin & gills lesions caused by injure or parasitic infection.  Carriers may play an important role in spreading of the infection  Snails  Arthropods CLINICAL SIGNS:  Varies - depending on the species of fish affected & water temperature  Emaciation with reducing of growth rate.  Loss of appetite of fish – anorexia  Ascites  Ulceration  Deformities of the vertebral column and mandible.  Fish show difficulties in maintaining balance.  Exophthalmia and loss of one or both eyes  Disease leads to loss of colouration in ornamental fish.  Loss of scales may be observed on the scales fishes.  Gills are paler than normal and show thickened areas on some filaments.  Nodules in liver, spleen & kidney DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA. TREATMENT AND CONTROL:  There is no suitable treatment  Mycobacterium spp. are mostly resistant to conventional antibiotics  Adding tetracycline to the water at dose 30 mg/l help in treatment of fish  Chloramine B or T at a concentration of 10 mg/l for 24h is recommended for bath treatment.  Kanamycin (0.01%) mixed with food was effective in treatment of disease among ornamental fishes. CONTROL OF DISEASE  Stress factors must be removed.  Dead fish must be removed & disposed - should be treated at 76 0C for 30 minutes.  Suspected or infected fishes should never be introduced in to a pond or aquarium.  Quarantine (2 months) is important in the ornamental fishes  Formalin or phenolic compounds should be used as disinfections in fish farm at which the disease have been recorded.  SPF Fish egg 7. BACTERIAL KIDNEY DISEASE  Renibacterium salmoninarum  Family salmonidae  Disease characterized by:  dark coloration of the skin  exophthalmia  greyish or white abscesses in the kidney and sometimes in visceral organs. CAUSATIVE AGENT:  Renibacterium salmoninarum  gram-positive  non motile  short bacilli  The optimum growth temperature is 15-17 0C  Disease appears within 4 weeks. SUSCEPTIBLE SPECIES:  Family salmonidae  Trout are also susceptible. MODE OF TRANSMISSION:  Horizontal transmission:  Via oral route, skin erosions through contaminated feed /water/other infected fishes  Vertical transmission:  through eggs.  Vectors : Fishes and bivalve molluscs  Carriers : salmonids species CLINICAL SINGS:  Darkness of the skin.  Gills are pale in color.  Exophthalmia  Haemorrhages at the base of the fins.  Abscesses on the skin. These abscesses may rupture lead to ulcer formation.  The body cavity has fluid. This fluid may be yellowish or bloody.  Swelling of the kidney.  Presence of small abscesses in the kidney and may also found in other internal organs. DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA. TREATMENT AND CONTROL:  BKD is one of the most difficult of fish diseases to treat with drugs  because micro-organism is found intracellular  The disease can treated with clindamycin, erythromycin, penicillin G, spiramycin, and lincomycin. CONTROL  Drying and disinfecting the farm / equipment  Restocking the fish farm with fish free from disease.  Control the wild fish from entering the fish farm.  The imported fish must be accompanied with certification that the fish free from disease.  SPF Fish egg  Prevent movement of infected fish or fish eggs from infected area to free one.  Proper diet  Prevent using of contaminated food or water. 8. ENTERIC REDMOUTH DISEASE (HAGERMAN RED MOUTH)  Pathogen - Yersinia ruckeri  Affects salmonids species as well as non salmonid species such as gold fish and carp  The disease is characterized by:  reddening in the mouth and throat or inflammation and erosion of the jaws and palate  darkening of the skin  Exophthalmia  inflammation of the intestinal tract.  a.k.a. “Hagerman Redmouth”  Rucker - First reported in 1958 in Hagerman Valley.  Named in 1978 Yersinia ruckeri CAUSATIVE AGENT  Yersinia ruckeri  gram negative  non spore-forming  straight - rod-shaped  Motile  Optimum temperature for growth is 22 0C MODE OF TRANSMISSION  Horizontal  contaminated food /water  Injuries of the skin or scales or gills may also act as route of infection.  The organism may be present in the alimentary tract and under stresses the bacterium may be invade the fishes.  Carriers - help in spreading the infection.  Contact between healthy and diseased one. STRESS FACTORS  Rise of water temperature.  Rough handling of the fish.  Overcrowding  Decrease in oxygen level.  Poor feeding. SUSCEPTIBLE SPECIES  Salmonids species  a few non-salmonids species - such as carp, eel, sole, channel catfish and goldfish are susceptible. INCUBATION PERIOD  five to ten days at 13 to 15 0C experimentally.  Water temperature and fish susceptibility is responsible for determination of the incubation period in all cases. CLINICAL SIGNS  The reddening of the throat and mouth because of subcutaneous haemorrhages and hence the name.  Erosion of the jaw and palate may occur.  Haemorrhages occurs on the body surface, at gills tips, at the base of the fins and around the lateral line.  Darkening of skin my also occur.  Fishes show partial or total blindness with exophthalmia in one or both eyes.  Some fishes show distended abdomen / may be emaciated.  Congestion of the blood-vessels  Haemorrhages found in liver, swim-bladder, lateral muscles and adipose tissues.  The kidney and spleen may be swollen.  Intestinal tract is congested and filled with bloody mucous especially the posterior part. DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA. MORTALITY & MORBIDITY  Young fishes are somewhat more susceptible to ERM disease than older fish.  Morbidity rate may be reach 100% in any age and class of fishes.  The mortality rate is usually higher in younger fishes but is dependent upon fish culture management. TREATMENT  Sulphamerazine: 265 mg/kg of fish/day for 3 days. Followed by 156 mg/kg of fish/day for 11 days.  Oxytetracyclin : 55 mg/kg of fish/day for 10 days.  Oxolinic acid: 10 mg/kg of fish/day for 10 days.  Sulphamerazine and Furazolidone: 66 mg/kg of fish and 44 mg/kg of fish / day for 15 days. CONTROL  Stress factors must be removed.  Keeping the water supply free from carrier fish  Eggs from infected brood stock should be treated with antiseptic solution.  Keep fish-eating birds and mammals away from fish culture.  Prevent movement of infected fish of suspected culture to non-infected ones.  Vaccination of fishes by oral route through feed or by immersion or injection helps in control of the disease. 9. PISCIRICKETTSIOSIS  Piscirickettsiosis is a disease of salmonids  caused by Piscirickettsia salmonis  a significant disease problem in farmed marine salmonids.  First reported in coho salmon in Chile in 1989 PATHOGEN  Gram-negative  non-motile  spherical to coccoid  non-capsulated HOST  Salmonids, particularly Pacific salmon vulnerable.  Carriers - Wild fish, shellfish - crustaceans all reported to harbor rickettsia but the true source not established.  Vectors (lice, isopods) may also be involved. SYMPTOMS  Skin lesions  dark skin  lethargy  Anorexia (loss of appetite)  nervous disorders in some cases  ascites  white nodules in liver and kidney  Meningitis also reported is various fish species. TREATMENT & CONTROL  Vaccines are used  Chemotherapy used, although some resistance developing  10. PSEUDOMONAS SEPTICAEMIA PSEUDOMONAS FLUORESCENS  Affectsmost species of fishes  caused by Pseudomonas sp.  The disease is characterized by:  septicemia  high mortality  normally a secondary invader  hard to distinguish from Aeromonas septicemia  not a huge concern in fish CAUSATIVE AGENT  Pseudomonas fluorescens  ubiquitous bacterium of soil, water  Pseudomonas anguilliseptica causes red spot disease in Japanese eel.  gram negative rod-shaped bacteria  non-spore-forming  all are motile  optimum temperature for growth is 20 to 25 0C. SUSCEPTIBLE SPECIES  All species of fishes are susceptible to Pseudomonas infection under stress conditions. STRESS FACTORS  Injuries or damage to skin or scales.  Reduced dissolved oxygen.  Presence of toxic substance in the water.  pH variation  Overcrowding of the fishes in farm.  Malnutrition.  Heavy infestation with parasites. MODE OF TRANSMISSION  Horizontal:  The pathogen enters the host either through the oral route or through broken or abraded skin  Damaged gills are also act as route of infection.  Carrier fishes may play a role in spreading of the disease. CLINICAL SIGNS  Erythema (reddening of skin) - at the base of fins, in the mouth under the lower jaw and around the anus.  Small haemorrhages  The liver may be pale and haemorrhagic  Kidney may be soft and liquefying  Ascites DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA.  TREATMENT AND CONTROL  Treatment:  oxytet (@50-75 mg/kg/f/day for 10 days)  no vaccine yet  Control 1. The stress factors must be removed. 2. Good management of the fish farm. 3. External disinfection reduces spreading of the disease.  11. BACTERIAL GILL DISEASE (FLAVOBACTERIUM BRANCHIOPHILUM)  Gill infections primarily in juvenile fish  F. branchiophilum – pathogen  affect primarily cultured and aquarium fishes  Disease characterized by respiratory and osmoregulatory impairment CAUSATIVE AGENT  Gill disease is caused by several agents:  Myxobacteria (Flavobacterium branchiophilum) in combination with unfavorable environmental conditions. This type termed (bacterial gill disease).  Deficiency of pantothenic acid (Vit-B5). This type is called nutritional gill disease.  Chemical pollution or pesticides with secondary mycotic infection (Haemorrhagic gills disease). STRESS FACTORS 1. Low oxygen content. 2. High turbidity of water. 3. High ammonia in water. 4. Change in pH of water. 5. Over stocking in fish farm. 6. Malnutrition of fish. 7. Mechanical injuries of the skin or gills. 8. Toxic inorganic and organic substances. HOSTS  Wide range of hosts  Mainly salmonids  Occurs in warm water fishes  Carp, goldfish, catfish, eel and other fishes  Fry stage more susceptible than adults TRANSMISSION  Transmission – horizontal - water to fish  disease can be transmitted through injuries of gills  Reservoir – not clear  Infected fish, mud, silt in water Environmental factors:  poor water quality, crowding, high organic matter, stress, temp fluctuation CLINICAL SIGNS  Food intake by fish is reduced.  Sluggish movement of affected fish.  increased mucous secretion by the gills.  Gills may be swollen and congested, which results in their appearance deep red than normal.  In advanced cases gills lamellae are clubbed and filaments may be fused together  white to grey spots on the gills DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA. MORTALITY AND MORBIDITY  Morbidity rate is high and may reach 100%  Mortality - 25% to 30%  Morbidity and mortality rate from bacterial gills disease are usually more severe than environmental gill disease. TREATMENT AND CONTROL  Antibiotics used for treatment of bacterial gill disease.  Quaternary ammonium compounds  Chloramine T  Oxytetracycline  External disinfectants are used for treatment such as potassium permanganate 100mg/l for 30 second.  Stress factors must be removed.  Good management of the fish farm. 12. COLUMNARIS DISEASE (SADDLE BACK DISEASE) - FLAVOBACTERIUM COLUMNARE  Flavobacterium columnare (formerly, Flexibacter columnaris)  Affects mainly fresh water fishes - but also occurs in brackish and sea water fishes CAUSATIVE AGENT  Flexibacter columnaris or Flavobacterium columnare  gram-negative rods  motile by gliding movement  Optimum - 4 and 30 0C STRESS FACTORS 1. Rise of water temperature above 20 0C. 2. Rough handling and transportation of fishes. 3. Overcrowding in fish farm. 4. Physical injury of fish. 5. Low oxygen content. 6. Organic pollution of water. 7. Nutritional deficiency especially vitamins. CHARACTERISTICS OF THE DISEASE  Rarely occurs unless fish is stressed  Most frequently occurs between March and October when water temperatures are higher SUSCEPTIBLE SPECIES  All freshwater fishes are susceptible to infection  Also occurs in brackish and seawater fishes.  Young fishes are more susceptible than adult ones. INCUBATION PERIOD  Varies from less than 24 hours - two to three days.  Depends on stress factors MODE OF TRANSMISSION Horizontal: 1. Injuries of the skin or gills help in transmission of the disease. 2. Movement of the infected fishes help in spreading of the infection. 3. Carriers transmit the infection among fishes. CLINICAL SIGNS  Lesions on body surface  Pale discoloration at the base of fin  Eroded skin  Gills necrosis- complete destruction  Increased mucous on skin  Saddleback appearance  Ulcers and lesions in skin leading to gray or colorless skin ulcers  Loss of appetite  Lethargy DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA. MORTALITY AND MORBIDITY  Morbidity rate of columnaris disease in unsanitary conditions may reach 100%.  Mortality rate under the same condition may reach 70% or higher among the young and most susceptible fishes. TREATMENT 1. Potassium permanganate: 500mg/100l for 1 hour by bath method. 2. Malachite green: 10mg/100l for 30-96 hours by bath method. 3. Oxytetracycline: 50-100mg/kg body weight of fish/day for 10 days. CONTROL  Stress factors must be avoided.  Proper nutrition - will reduce the rate of disease.  Lowering the temperature (adding cold water) will reduce disease severity.  Control of F. columnaris infection may be possible by immunization. 13. COLDWATER DISEASE / PEDUNCLE DISEASE FLAVOBACTERIUM PSYCHROPHILIUM  Bacterial cold-water disease - CWD  occurs more often in cold water fishes  caused by Flavobacterium psychophilum or Cytophaga psychophila  characterized by tissue necrosis of tissue at the base of the caudal fin (the caudal peduncle). PATHOGEN  Pathogen - Cytophaga psychrophila – then as Flexibacter psychrophilus – now as Flavobacterium psychrophilium  Long slender Gram-negative rod  motile by gliding movement  aerobic  Optimum temperature 4-23 0C  HOST RANGE AND VECTORS  All cold-water fishes are susceptible  Most of aquarium fishes are also susceptible to peduncle disease. STRESS FACTORS  Malnutrition of fish.  Presence of toxic substance in the water.  Rough handling of fish.  Elevation pH of water.  Poor water quality  Over crowding increase the incidence of the infection.  Presence of organic matter favors infection CLINICAL SIGNS CWD  Tissue necrosis of tissue at the base of the caudal fin (the caudal peduncle).  Rough appearance of skin  Erratic/spiral swimming  External lesions / ulcers on fins, skin, muscle  Inflammation and necrosis of the affected area.  Destruction and sloughing of fins.  The necrosis of muscle tissue continues and the vertebral column may be exposed before fish dies.  Development of deformities and/or nervous disorders DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA. MORTALITY AND MORBIDITY  Morbidity may range from 1% to 50% particularly where water temperature are below 10 0C.  Mortality may approach 70%. TREATMENT AND CONTROL  1. Potassium permanganate: 2mg/l by flush method.  2. Oxytetracycline in food: 50 mg/kg of fish/day for 10 days.  3. Sulpha drugs (sulphamethazine): 220mg/kg body weigh/day for 10 days.  4. Stress factors must be removed.  5. Good management of the fish farms or aquaria helps in control of the disease.  14. VIBRIOSIS  Vibriosis is one of the most prevalent fish diseases  caused by bacteria belonging the genus Vibrio  V.anguillarum, V. ordalii and V. salmonicida  affect many marine and fresh water fishes  The disease is characterized by:  Septicemia  Dermal ulceration  Ascites  Necrosis CAUSATIVE AGENT  Mainly V. anguillarum  Gram negative  motile  non-sporulating  non-capsulated  Vibrio sp. ubiquitous in marine and brackish water  Bacterial number high - high organic load.  Incubation:  Incubation period may be short (3 days)  This depends on virulence of the pathogen and susceptibility of the fishes. SUSCEPTIBLE SPECIES  At least 50 species of fishes are known to be susceptible to V.anguillarum infection  Most are marine & estuarine fishes (salmonids, mackeral, herring etc.).  Fresh water fishes are also susceptible to vibriosis include carp, eel and tilapia. STRESS FACTORS 1. High water temperature. 2. Over crowding in fish farm. 3. Organic pollution of the water. 4. Poor nutrition. 5. Poor water quality. 6. Improper handling. MODE OF TRANSMISSION  Horizontal:  The infection may be transmitted through oral route.  External injures and external parasites may play a role  Carriers may be playing a role in spreading of the infection.  Contact between diseased fish & healthy one. CLINICAL SIGNS  Anorexia, anaemia, darkening of the skin, red spots on skin, ulcers, hemorrhages, abdominal distension  Congestion and swelling of the spleen, liver and kidney.  Presence of clear viscous fluid within the intestinal tract.  Eyes are affected - lesions with oedema, ulceration and exophthalmia.  Fin rots and paleness of gills may be show in chronic infection. DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA. MORTALITY AND MORBIDITY  Morbidity rate may reach 100%.  Mortality rate among susceptible fishes may reach 80% TREATMENT AND CONTROL  Broad spectrum antibiotics effective  Increasing antibiotic resistance is observed  Sulphamerazine : 12gm/100lb of fish/day for three days followed by 7 gm/100lb of fish/day for 11 days.  Oxytetracycline: 3-5gm/100lb of fish/day for 10 days.  Furazolidone in feed: 100mg/kg/fish/6days. Vaccination:  Formalin-killed vaccine - very effective  administered via injection TREATMENT AND CONTROL  Stress factors must be avoided.  Good management of fish farm.  Disinfection of the fish egg, equipment, pond.  Feeding the viscera of infected fish as sources of protein to healthy one should be avoided.  Fishes from infected farm should be not move to non-infected areas.  Quarantine of new fish and good sanitation will minimize the spread of infection.  15. PHOTOBACTERIOSIS /PASTEURELLOSIS / PSEUDOTUBERCULOSIS  disease of marine and brackish water fishes  caused by Photobacterium damselae subsp. piscicida (formerly - Pasteurella piscicida)  characterized by white granulomatous lesions in the internal organs. CAUSATIVE AGENT  Photobacterium damselae subsp. piscicida  Gram negative  non-motile rod  multiple drug resistance SUSCEPTIBLE SPECIES  A variety of fish species  Perches, striped bass, black sea bream, red sea bream, groupers CLINICAL SIGNS  Characterized by white granulomatous lesions in the internal organs.  Redness in the operculum  Enlargement of the spleen  Haemorrhages of the gills  Necrosis in spleen and kidney  Oedema DIAGNOSIS:  Case history  Clinical signs  Postmortem findings  Microbiology - Isolation and identification of the causative agent.  Serological identification of the etiology by:  a. Agglutination test.  b. Precipitation test.  c. Fluorescent antibody technique.  d. ELISA. TREATMENT AND CONTROL  Oxytetracycline, Romet, oxolinic acid, ampicillin and amoxicillin medicated feeds.  Commercial vaccines are currently in the developmental stage. 16. INFECTIOUS DROPSY  16. DROPSY  Dropsy is the build up of fluid inside the body cavity or tissues of a fish.  a symptom rather than a disease  it can indicate a number of underlying diseases, including bacterial infections, parasitic infections, or liver dysfunction.  Because dropsy is a symptom of an illness, its cause may or may not be contagious.  However, it is standard practice to quarantine sick fish to prevent spreading Bacterial Dropsy CHARACTERISTICS  Dropsy in fish is characterised by a swelling of the abdomen.  A.k.a ascites — is the accumulation of fluids in the visceral cavity of a fish.  Exophathalmia  Scale protrusion - In severe cases the distension is so great that the scales stand out from the body.  It often causes the fish scales to stick out and gives the fish a “pine cone” like appearance.  They also appear listless / lethargic and have a loss of appetite. PATHOGEN  the most common cause of dropsy is internal bacterial infection.  Several bacterial diseases including:  Aeromonad disease (Aeromonas hydrophila)  Pseudomonad septicemia (Pseudomonas fluorescens, Pseudomonas punctata)  Vibriosis (Vibrio anguillarum) — can result in dropsy. TREATMENT & PREVENTION  Dip treatment in 5ppm potassium permanganate solution for 2 minutes  Monitor and maintain healthy water chemistry  Observe your fish daily for signs of stress  Don’t overcrowd your tank  Feed a good quality food  Maintain an appropriate water temperature.  17. STRAWBERRY DISEASE  A.k.a Red Mark Syndrome/ Cold Water Strawberry Disease  A severe dermatitis affecting the rainbow trout Oncorynchus mykiss  Cause  Bacterial  Allergic reaction  Symptoms  Rough reddened areas on the body surfaces  Reddened raised inflammation on skin  Morbidity 10-15%  18. FIN & TAIL ROT Aetiological agent:  Vibrio, Aeromonas, Pseudomonas  It affect both adult and young Symptoms:  Infection during its early stage appears as a white line on the margin of the fin, fin rays become brittle and start breaking, eventually putrefies and disintegrates Treatment:  1 minute dip treatment in 500ppm copper sulphate solution. THANK YOU