Important Bacterial Diseases of Fish - PowerPoint Presentation

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Important Bacterial Diseases of Fish

Dr Deepak KumarAssistant ProfessorDepartment of Veterinary Pathology Bihar Veterinary College, PatnaBihar Animal Sciences University, Patna - 14

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Body Parts Of Fish

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BACTERIAL DISEASES

Bacterial fish diseases and infection are very common in fish. The key to successful treatment of bacterial disease is early, accurate diagnosis and treatment. If treatment is delayed it can lead to substantial losses. There are two types of pathogenic bacteria namely 1.) Primary or obligate pathogens

2.)Opportunistic pathogens

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BACTERIAL DISEASES

Primary or obligate pathogens these are not part of the normal aquatic flora and are capable of causing disease in healthy individuals, eg. Aeromonas salmonicida.

Opportunistic pathogens These are normally free-living, either in the water or on the fish, but becomes pathogenic under certain circumstances.

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BACTERIAL DISEASES

Many of these are saprophytes, normally living on dead organic matter such as plant and animal remains or faeces, e.g., Aeromonas hydrophila and Pseudomonas spp. In general, most of the bacterial diseases that affect fishes are caused by opportunistic bacteria. Some of the common bacterial

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Furunculosis

The disesase is also known as – Salmon furunculosis, Ulcer disease, Goldfish ulcer disease.In Asia goldfish mainly affected Etiology – Aeromonas salmonida

1st

reported by Emmerich & Weibel

( 1984) I Germany

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Pathology

In chronic cases – Haemorrhage in vent, viscera, gills & muscles

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Furunculosis

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Post- Mortem Lesions

Haemorrhages are common in liver, spleen & kidney.

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Infectious Dropsy/

AeromoniasisIt is caused by – Aeromonas hydrophila which is associated with

Aeromonas septcaemia or red spot.

It means generally swelling of soft tissues due to the accumulation of excess water. swollen and scales standing out from the body.

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Infectious Dropsy/

Aeromoniasisis a heterotrophic, Gram-negative, rod-shaped bacterium mainly found in areas with a warm climate

Aeromonas

hydrophila -

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Aeromonas

hydrophila -

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Sine

The infected fish suffers from inappetiteAbnormal swimmingGill become pale I appearance.

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Infectious Dropsy/ Aeromoniasis

the swollen eyes and gill covers and the reddening of the belly and fin pits.

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Lesions

Skin ulcer is common at any site of fish and is often surrounded by bright red area.

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Infectious Dropsy/ Aeromoniasis

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Bacterial gill disease

It is caused by – Flavobacterium branchiophilum

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Bacterial gill disease

Flavobacterium is a genus of gramnegative, nonmotile and motile, rod-shaped bacteria 

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Flavobacterium branchiophilum

This bacterium can be found in fresh or brackish water. It can survive in aerobic and anaerobic environments

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Flavobacterium branchiophilum

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Pathogenesis

The bacteria normally reside in gill mucous of fish.After multiplication of bacteria, gill becomes proliferated, fusion of lamellae of gill occures.The bronchial mucosa cells secrete more mucous.

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Gills becomes proliferated.

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Gill rot

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Edwardsiellosis/fish Gangrene

It is also known as – Emphysematous putreactive disease ( EPD)1st reported by Hoshima ( 1962) from Japan.

It is caused by – Edwardsiella tarda.

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Edwardsiella

tarda.The bacterium is a facultatively anaerobic small, motile, gram negative, straight rod with flagella.

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Pathogenesis

The bacteria produces hemorrhage is surrounded by large area of depigmentation, over skin.After death of cell, purification ( pus formation in necrotic tissue by saprophytic bacteria), hydrogen ( H2 S)sulphide gas is produced so emphysematous purification disease ( EPD) .

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Edwardsiellosis/fish Gangrene

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Edwardsiellosis (

edwardsiella tarda) in channel catfish hemorrhage – pale skin and petechial.

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Edwardsiellosis/fish Gangrene

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Pseudomoniasis/ Pseudomonas

Septicaemia.Caused by – Pseudomonas fluorescens.Pseudomonas fluorescens is a common Gram-negative, rod-shaped bacterium.

Ascites is most common.

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Pseudomoniasis/ Pseudomonas

Septicaemia.After death of cell, inflammation starts, after puterification hyderogen sulphide gas is produced as termed as emphysematous putrifactive disease.

Carps are severely affected.

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Pseudomoniasis/ Pseudomonas

Septicaemia.

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Enteric Red mouth/Haemorrhagic

Septicemia Caused by – Yersinia ruckeri Yesinia ruckeri is a species of Gram-negative bacteria, known for causing enteric red mouth disease in some species of fish. Strain 2396-61 (= ATCC 29473) is its type strain. A draft genome for 

Yersinia ruckeri 

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Yersinia

ruckeri

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Classical lesions

1. Exophthalmus2. Partly opened lower jaw3. Haemorrhages present in the roof of mouth4. Mouth becomes darken due to improper melanin control5. Anemia due to necrosis haematopoetic tissue.

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Enteric Red mouth/Haemorrhagic

Septicemia A: darkening of the skin, enlarged abdominal valley (black arrow

), and hemorrhages in the dorsal fin (white arrow). B

: hemorrhages in and around the mouth (arrows). C: enlarged and black spleen (

white arrow

), and reddened intestine (

black arrow

).

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Enteric Red mouth/Haemorrhagic

Septicemia Histological sections of spleen and kidney organs of rainbow trout infected with Y. ruckeri 

. A: multifocal necrosis can be seen in the spleen. B: degeneration of interstitial tissue and a marked increase in melano-macrophages can be seen in the kidney. Sections were stained with haematoxylin and eosin (H&E).

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Common Freshwater prawn diseases in India

Larval midcycle disease (MCD)Bacterial necrosis – mortality up to 100% Black spot disease caused – by Beneka sp.Branchiostegite melanization – unknown

etiIdiopathic muscle necrosis by environmental dismanagement

.Isopod parasitic disease by probopyrus origin.

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Common Freshwater prawn diseases in India

VII. Epibiont fouling disease caused by various bacteria, algae, fungi, protoza etc.VIII. White muscle syndrome/white tail disease- by Nodavirus.

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BACTERIAL DISEASES

diseases

are:

Bacterial disease

Causative agent 

Symptoms

Columnaris

/ Saddleback Disease

Flavobacterium

columnare

Brown to yellowish brown lesion (sores) on their gills, skin, and/or fins.

Characteristic lesion produced by columnaris is a pale white band (often persists as whitish plaques) encircling the body, often referred to as saddle back.

Edwardsiellosis

/ Fish

Gangreen

Edwardsiella

tarda

Red

cutaneous

lesions located

dorso

-ventrally on the body

Abscesses resulting in loss of pigmentation with a large amount of necrotized tissue.

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BACTERIAL DISEASES

MycobacteriosisAcid-fast bacteria of the genus 

Mycobacterium

Mycobacterium fortuitum and Mycobacterium

marinum

Anorexia, emaciation and loss of equilibrium, inflammation of the skin, exophthalmia,

ascites

, and open lesions, and ulceration characterize tuberculosis.

Internally, grey-white

granulomas

develop in the

 

liver

,

kidney, spleen, heart and muscles.

Skin

discolourations

on one side of head or body

Motile aeromonad septicemia (MAS)

Aeromonas

hydrophila

Manifested by several clinical signs like ulceration, exophthalmia, abdominal

distention

etc.

Tail rot and fin rot

Various bacteria such as 

Aeromonas

, Pseudomonas 

and 

Mycobacterium

Fin rot and tail rot leads to the destruction of the fins especially the caudal fin.

This is usually caused due to poor environmental conditions, poor nutrition and stress.

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Vibriosis

Vibrio

anguillarum

Red spots on the ventral and lateral areas of the fishes. Swollen dark skin lesions releasing blood

exudate

.

In acute epizootics, the infected fish die without showing any clinical signs

Vibriosis of shell fish

Vibrio

 spp.

High mortalities in post-larvae, young juveniles

Moribund shrimp appear hypoxic and often come to the pond surface or edge.

Presence of luminescence in tanks

Necrotizing Hepatopancreatitis

Proteobacteria (alpha) group

Reduced feed intake, empty gut, anorexia, poor length: weight ratios, pallid

hepatopancreas

, reduced lipid droplets,

melanization

of tubules

Bacterial infection in marine fish

Reddening of 

mouth

 in catfish

Bacteri

ial

ulcer

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Furunculosis

Aeromonas

salmonicidae

Hemorrhages at the base of fins and erosion of the pectoral fins

Bloody or hemorrhagic vents and

petechial

hemorrhages

Furuncles or blisters all over the body of the fish

Enteric red 

mouth

disease

Yersinina

ruckeri

Septicemia

with

exophthalmus

,

ascites

, hemorrhage and ulceration of the 

jaw

, gills and operculum, swelling of the kidneys

Flavobacteriosis

Flavobacterium

 spp.

This disease is a cause of concern to primarily hobbyist and producers of ornamental fish (Mollie

granuloma

, Mollie madness, Mollie

popeye

).

Infected fish are usually emaciated and pale.

Multifocal white nodules are observed in the visceral organs, the retina and choroid and the 

brain

.

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Streptococcosis

Streptococcus iniae

Acute fulminating

septicemia, haemorrhage of the fins, skin, and

serosal

surfaces,

granulomas

or

granulomatous

inflammation are evident in the 

liver

, kidney, and 

brain

 (

meningoencephalitis

).

Rainbow trout fry anemia

Cytophaga psychrophila

Fish develop abdominal

distention

,

exophthalmus

, increased pigmentation, lethargy, loss of balance, pale gills, and occasional

cutaneous

ulcers and necrosis of tail fins.

Splenomegaly

and

hepatomegaly

are common with multifocal necrosis of the 

liver

 spleen and kidney.

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Bacterial kidney disease

Renibacterium salmoninarum

Exophthalmus, skin darkening, and hemorrhage at the base of the fins.

Cutaneous vesicles and ulcers may develop in mature trout "spawning rash".

The large swollen kidney and spleen have numerous white nodules visible in the parenchyma

Numerous

granulomas

(containing gram positive bacteria) are observed in the kidney and may be also present in the spleen, heart and 

liver

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Epitheliocystis

Chlamydia sp.

Clinically infected fish may be asymptomatic or show respiratory distress or excessive mucus secretions.

Multiple white cysts are observed on the gill lamella and skin.

 

Fish infected with

mycobacteriosis

Fish infected with

Aeromonas

 

sp

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Thanks

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