Fish Diseases: Enteric Septicemia Diagnosis

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Questions and Answers

Which of the following is a method for diagnosing Enteric Septicemia of Catfish?

  • Isolation and identification of the causative agent (correct)
  • Only blood tests
  • Observation of fish colors
  • Visual inspection only

Birds can contribute to the transmission of infection among fish by dropping infected carcasses into healthy ponds.

True (A)

What is the primary causative agent of Enteric Septicemia of Catfish?

Edwardsiella ictaluri

In Enteric Septicemia, the bacterium Edwardsiella ictaluri is often found in the _____________ of the infected fish.

<p>intestinal tract</p> Signup and view all the answers

Match the clinical signs of infection with their corresponding descriptions:

<p>Sudden decrease in feeding = Loss of appetite and reduced food intake Pale colouration of skin = Lightening of the fish's skin and gills Exophthalmia = Protrusion of the eyes Hemorrhages = Bleeding around fins and body</p> Signup and view all the answers

Which of the following is a potential consequence of stressed fish that contribute to susceptibility to infection?

<p>Increased risk of bacteria invasion (C)</p> Signup and view all the answers

Microbiology techniques such as the agglutination test are used for serological identification of the pathogen.

<p>True (A)</p> Signup and view all the answers

List two transmission pathways for diseases among fish populations.

<p>Birds and contaminated nets/equipment</p> Signup and view all the answers

Which of the following species is most susceptible to Edwardsiella tarda?

<p>Channel catfish (B)</p> Signup and view all the answers

Mycobacterium spp. can cause disease in both freshwater and saltwater fish.

<p>True (A)</p> Signup and view all the answers

Name one clinical sign associated with fish infected by Edwardsiella tarda.

<p>Exophthalmia</p> Signup and view all the answers

Edwardsiella tarda is transmitted through the ______ and oral cavity.

<p>gills</p> Signup and view all the answers

Which treatment is recommended for 10-14 days with a 21 day withdrawal period?

<p>Terramycin (D)</p> Signup and view all the answers

Match the disease with its characteristic sign:

<p>Edwardsiella tarda = Spiraling swimming behavior Mycobacteriosis = Greyish nodules in internal organs Fish mycobacteriosis = Emaciation Mycobacterium marinum = Inflammation of the skin</p> Signup and view all the answers

The agglutination test is one method used for _______ identification of the causative agent.

<p>serological</p> Signup and view all the answers

Reducing stress in fish is a control strategy for preventing mycobacterial diseases.

<p>True (A)</p> Signup and view all the answers

What is one of the most common causes of Pop Eye in fish?

<p>Injury to the eyes (D)</p> Signup and view all the answers

The disease Edwardsiellosis is caused only by the bacteria Edwardsiella tarda.

<p>False (B)</p> Signup and view all the answers

Name one treatment method for Pop Eye disease in fish.

<p>Separate the affected fish or treat with an antibacterial agent.</p> Signup and view all the answers

The bacteria Aeromonas liquifaciens is commonly associated with __________ in fish.

<p>eye disease</p> Signup and view all the answers

Match the following stress factors with their potential effects on fish health:

<p>Fluctuating temperature = Increases susceptibility to diseases Low dissolved oxygen = Reduces fish resilience High ammonia = Causes stress and potential fatalities Improper diet = Weakens the immune system</p> Signup and view all the answers

Which species are known to be most susceptible to Edwardsiella tarda infections?

<p>Eels and catfish (B)</p> Signup and view all the answers

Horizontal transmission of bacterial infections can occur through faeces.

<p>True (A)</p> Signup and view all the answers

What is the optimum growth temperature range for Edwardsiella spp. bacteria?

<p>26 to 30 °C</p> Signup and view all the answers

Flashcards

Edwardsiella tarda

A bacteria similar to that causing a disease in fish.

Channel Catfish

Fish most susceptible to Edwardsiella infection.

Swimming Behavior Changes

Fish show spiraling, and star gazing in Edwardsiella.

External Ulcers

Open sores on fish bodies.

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Transmission - Horizontal

Disease spread between fish (via water, cannibalism, carriers, etc).

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Diagnosis - Microbiology

Identifying the bacteria causing the disease through lab tests.

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Treatment - Medicated Feeds

Using medicine in fish food to treat disease.

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Mycobacteriosis

Bacterial disease in fish caused by Mycobacterium.

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Emaciation

Severe weight loss in fish.

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Stress Factors

Conditions that make fish more prone to disease.

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Carriers & Vectors

Animals that transmit diseases between hosts, e.g., birds carrying infected fish carcasses.

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Enteric Septicemia of Catfish (ESC)

A common bacterial disease in catfish farms, caused by Edwardsiella ictaluri.

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Edwardsiella ictaluri

The bacterium that causes Enteric Septicemia of Catfish.

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Clinical Signs of ESC

Observable symptoms like decreased feeding, unusual swimming, and skin lesions in infected fish.

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Stress on Fish

Factors that can cause a fish to be more susceptible to diseases such as ESC. This includes inadequate conditions and any stress factors.

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Postmortem Findings

Physical examination of a dead fish to identify the cause of death. Example: abnormal organs, such as pale or bloody spots.

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Microbiology Diagnosis

Identifying the disease-causing organisms in a lab through isolation, culture and identification methods.

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Serological Identification

Using lab tests to identify a disease-causing agent in fish, like detecting antibodies against specific bacteria.

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Pond Drying and Disinfection

A crucial step in fish farm management to prevent disease spread. Involves drying and disinfecting ponds and equipment.

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Fish and Water Transportation Prevention

Stopping the movement of fish and water from infected areas to prevent disease transmission.

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Pop Eye Symptom

Abnormal swelling of the fish eye, a symptom of underlying issues, not a disease itself.

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Pop Eye Causes

Common causes include injury, infection, and poor water quality.

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Aeromonas Liquifaciens

A type of bacteria that causes disease, typically eye problems.

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Edwardsiosis

A bacterial disease impacting various fish species, causing septicaemia (blood poisoning) and abscesses.

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Edwardsiella spp.

The bacteria responsible for Edwardsiella disease, found in fish and other animals.

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Septicaemia

Blood poisoning caused by bacteria.

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Abscess Formation

Accumulation of pus in localized tissue, a symptom of infection.

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SPF Fish Eggs

Disease-free fish eggs; important for starting disease-free fish populations.

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Study Notes

Bacterial Diseases of Finfishes

  • Bacterial diseases are common in finfish.
  • Most are opportunistic pathogens.
  • Pathogens include anaerobes, aerobes, gram-negative, and gram-positive bacteria.
  • Clinical signs are non-specific and include lethargy, loss of appetite, skin hemorrhages, ulcers, fin rot, ascites (dropsy), eye bulging, and color changes.

Pathogens and Diseases (Anaerobes)

  • Clostridium botulinum: Botulism
  • Eubacterium sp.: Meningitis

Pathogens and Diseases (Aerobes - Gram-Positive)

  • Coryneform bacteria: Corynebacteriosis
  • Lactobacillus: Lactobacillosis/pseudokidney disease
  • Mycobacterium: Mycobacteriosis/fish tuberculosis
  • Nocardia: Nocardiosis
  • Renibacterium salmoninarum: Bacterial kidney disease
  • Streptococcus iniae: Streptococcosis

Pathogens and Diseases (Aerobes - Gram-Negative)

  • Edwardsiella tarda: Edwardsiellosis/Edwardsiella septicemia
  • Edwardsiella ictaluri: Enteric septicemia
  • Yersinia ruckeri: Enteric redmouth disease
  • Aeromonas hydrophila: Haemorrhagic septicaemia/Motile Aeromonas septicemia
  • Aeromonas salmonicida: Furunculosis
  • Aeromonas sp.: Fin rot
  • Aeromonas liquifaciens: Eye disease

Pathogens and Diseases (Other)

  • Flexibacter: Fin rot
  • Myxobacterium: Bacterial gill disease
  • Pseudomonas sp.: Red spot, generalized septicemia, fin rot
  • Pseudomonas fluorescens: Pseudomonas septicemia
  • Pseudomonas punctata: Dropsy
  • Piscirickettsia salmonis: Piscirickettsiosis
  • Vibrio alginolyticus: Septicemia
  • Vibrio sp.: Vibriosis

Diseases Considered Bacterial in Origin

  • Bacteria: Strawberry disease
  • Aeromonas, Pseudomonas, Vibrio: Fin and tail rot

Major Bacterial Pathogens

  • Aeromonas: Aerobic Gram-negative cocci, significant resistance to tetracycline and sulfamerazine.
    • A. salmonicida: Furunculosis
    • A. hydrophila: Motile Aeromonas Septicemia
    • A. liquefaciens: Eye disease
  • Edwardsiella: Aerobic Gram-negative cocci, important bacterial pathogen of fish.
    • E. tarda: Edwardsiellosis
    • E. ictaluri: Enteric septicemia
  • Yersinia: Aerobic Gram-negative cocci, important pathogen of salmonids.
    • Yersinia ruckeri: Enteric Redmouth Disease
  • Mycobacterium: Aerobic – acid fast, mycobacterial infections/Mycobacteriosis, caused by Mycobacterium marinum, Mycobacterium chelonae, Mycobacterium fortuitum
  • 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, primarily pathogens of marine fish,
    • Vibriosis - V. damsela, V. alginolyticus, V. anguillarum
  • Flavobacterium: Aerobic-Gram-negative rods, Columnaris infection- Flavobacterium columnare, Bacterial Gill Disease - Flavobacterium branchiophilum, Coldwater Disease / Peduncle disease - Flavobacterium psychrophilium

Aeromonas Hydrophila (MAS)

  • A. hydrophila: opportunistic pathogen, causes Motile Aeromonas Septicemia, affects all freshwater fishes, characterized by fatal septicemia, exophthalmia, ascites/dropsy, and ulcer formation
  • different serotypes observed in fish from various places and times.
  • Gram negative, motile, non-spore forming, aerobe or facultative anaerobe

Susceptible Species (A. hydrophila)

  • Carp
  • Channel catfish
  • Eel
  • Goldfish
  • Trout
  • Tilapia

Predisposing/Environmental Factors (A. hydrophila)

  • High temperature
  • Overcrowding
  • Reduced oxygen
  • Malnutrition
  • Heavy parasite infestations
  • Organic pollution
  • High ammonia/nitrite levels
  • Injuries/damage to skin/gills.
  • Rough handling/transportation

Transmission (A. hydrophila)

  • Horizontal transmission
  • Distribution wide in water/sediments of ponds
  • Transmitted external lesions/intestinal tract discharge.
  • Parasitic/fungal infection may allow infection spread

Incubation Period (A. hydrophila)

  • Depends on environment's temperature
  • Acute cases may appear 4-10 days after infection.

Clinical Signs (A. hydrophila)

  • Fatal septicemia
  • Exophthalmia
  • Ascites/dropsy
  • Ulcer formation

Mortality (A. hydrophila)

  • 80% mortality in fish farms if fish under stress

Diagnosis (A. hydrophila)

  • Case history
  • Clinical signs
  • Postmortem findings
  • Microbiology – isolation and identification causative agent
  • Serological identification of etiology by agglutination test, precipitation test, fluorescent antibody technique, ELISA

Treatment and Control (A. hydrophila)

  • Oxytetracycline
  • Sulfamerazine
  • Prolonged potassium permanganate/1–3% NaCl bath treatments
  • Avoid stress factors
  • Good hygiene
  • Periodic pond drying
  • Disinfection of ponds
  • Disinfection of eggs with acriflavine or betadine

Furunculosis

  • Causative agent:Aeromonas salmonicida
  • Characterized by furuncle or boil-like lesions in various body tissues.
  • Mostly associated with salmonids, but other fish can be affected.
  • Obligate pathogen (fish to fish transmission).
  • Gram negative, short bacilli, aerobic & facultative anaerobe, non-motile, non-spore forming

Susceptible Species (Furunculosis)

  • All species of salmonids
  • Carp
  • Catfish

Incubation Period (Furunculosis)

  • Depends on water temperature.
  • At 20 °C – 4 to 20 days

Predisposing or Environmental Factors (Furunculosis)

  • Low water quality
  • Physical skin damage or gill damage
  • presence of ectoparasites/other diseases
  • high temperature.
  • High-density stocking

Transmission (Furunculosis)

  • Primarily horizontal transmission - from fish to fish through contaminated water
  • carriers may be involved

Clinical presentation of Furunculosis

  • Rapid death, especially of young fish.
  • Raised furuncles (boil-like lesions).
  • Haemorrhages & skin lesions
  • Darkening of skin
  • Rapid breathing
  • Exophthalmia
  • Lethargy
  • Soft and liquefied kidney
  • Enlarged spleen
  • Pale liver, with haemorrhages
  • Bloody mucous in the stomach and intestine
  • Hyperaemic swim bladder.
  • Fish may die within 2–3 days.

Diagnosis (Furunculosis)

  • Case history
  • Clinical signs
  • Postmortem findings
  • Microbiology – isolation & identification of causative agent
  • Serological identification method (agglutination, precipitation, fluorescent antibody, and ELISA)

Treatment (Furunculosis)

  • Sulfamerazine: 150–220 mg/kg fish wt/day for 10-14 days.
  • Oxytetracycline: 50–75 mg/kg fish wt/day for 10 days.
  • Furazolidone: 25–100 mg/kg fish wt/day for 10 days.
  • Oxolinic acid: 10 mg/kg fish wt/day for 10 days

Control (Furunculosis)

  • Stress factors removed.
  • Pond drying & disinfection
  • Disinfection of equipment
  • Prevent fish/water movement to uninfected areas
  • SPF fish eggs

Additional topics (with relevant sections):

  • Aeromonas Liquefaciens (Pop Eye)
  • Edwardsiellosis
  • Enteric Septicemia of Catfish (ESC)
  • Mycobacteriosis
  • Bacterial Kidney Disease (BKD)
  • Enteric Redmouth Disease (Hagerman Red Mouth)
  • Piscirickettsiosis
  • Pseudomonas Septicemia
  • Vibriosis
  • Bacterial Gill Disease (F.branchiophilum)
  • Coldwater Disease (F.psychrophilum)
  • Columnaris Disease (F.columnare)
  • Infectious Dropsy
  • Strawberry Disease
  • Fin & Tail Rot

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