Dr. Mohamed Sayed Mohamed MarzoukProfessor of Fish Diseases and Management , Faculty of Veterinary Medicine ,

Cairo University

By

Parasitic Diseases of cultured fishes

� What is meant by Parasite ?

Classification of different parasites

Protozoa (unicellular).

Helminthes (multi-cellular) Crustaceans

Protozoa

According to habitate:

1. External.

2. Internal (Blood and Tissue).

According to shape:

1. Cilliates (Icthyophthirius, Chilodonella, Trichodina).

2. Flagellates (Ichthyopoda, Trypanosoma, Cryptobia, Hexamita).

3. Sporozoa (Myxosoma).

External protozoa

1. Exteranl cilliated protozoa:

Ichthyophthirius multifillis

Chilodonella spp.

Trichodina spp.

2. Exteranl flagellated protozoa:

Ichthyoboda (Costia) necatrix and pyriformis

Piscinoodinium spp.

Amyloodinium spp.

3. Internal flagellated protozoa

Cryptobia spp.

Hexamita spp.

Trypanoplasma spp.

Ichthyophthirium multifilis trophozoit (Stained )

Ichthyophonus multifillis (unstained)

Stained Trichodina from skin mucus scraping

Pathogenesis of external protozoa

Protozoal invasion

Skin cellular irritation 1. Abnormal swimming

2 .Excessive mucus

Skin cellular destruction

1. Haemorrhages

2. Erosions and ulcers

3. C.T capsules (White spots).

Life cycle of Ichthyophthiriosis

Clinical signs

Abnormal swimming ( Flashing, circling, sluggish and itching ).

Surfacing and gasping ( Asphyxia ).

Excessive skin mucus ( patchy then generalized ).

Pathognomonic white spots (Ichthyophthiriosis), Yellow

shine or Rust (Oodiniosis).

Emaciation and death.

Skin haemorrhages, erosions and ulcerations.

White spot disease

Cryptocarion irritans infection in marine fish

Surfacing and gasping in gill infection

Diagnosis of External parasitic Diseases

1. History ( new introduced fish, water parameters,………

2. Clinical signs and lesions.

3. Demonstration and identification of the causative parasites

Skin and gill mucus scraping (wet mount).

Stained skin and gill mucus smears.

Treatment of External parasitic Fish Diseases

External chemical treatment

Dip treatment Bath treatment Flush treatment Indefinite bath treatment

Non-chemical treatment

Increase water temperature in White Spot disease Change water facility Use of ultraviolet radiation in re-circulating system

Types of Chemical treatments

1 .Disinfectants:

Pot. Permenganate.

Malachite green.

Formaline.

Na Cl.

Acriflavin.

Methylene blue.

2. Pesticides:

Chlorinated Hydrocarbones.

Organophosphates.

Control of Fish diseases in infected fish farms

In infected earthen ponds:

o Drainageo Drynesso Disinfection using quick lime

In infected concrete or fiberglass fish tanks:o Drainageo Disinfection with strong antiseptics

Hexamitiosis

Systemic infection caused by an internal flagellated protozoa

Causative protozoa

Hexamita truttae Hexamita salmonis

Hexamita intestinalis

Mode of infection and transmission:

1. Infection through ingestion.

2. Transmission is from dead fish and contaminated water body.

Pathogenesis

Hexamita is normal inhabitant of intestine

Small numbersLarge numbers

Intestinal irritation

Intestinal destructionNo signs

Excess mucus

Systemic form

Off food & emaciation

Hole in head

Clinical signs:

1. Off food.

2. Emaciation and tucked up abdomen.

3. Mucus shreds from the vent.

4. High mortality in severe cases.

5. Hole in the head in systemic form (Fistula behind the head

exuding white material).

Diagnosis

Clinical signs and lesions (Non-confirmative)

Laboratory ( Confirmative)

Sampling ( Intestinal mucus )

QualitativeQuantitative (Count/ MF)

0 - 5 = Negative

5 – 15 = Mild

15 -30 = Moderate

30 – 100 = Severe

More than 100 = Marked

Treatment and control

1. Expulsion

2. Hexamiticides

Saline purgative

(MgSO4)1. Aresenical

(Carbersone).

2. Murcurial (Calomel).

Not to be used in food fishes

Sulfonamides

Can be used in food fishes

Fish Helminthosis

Helminthes infection or infestation ?

Helminthes of fishes

Platy helminthes

Round worms

Trematodes

Cestodes Larvae A dults

Fish Trematodes

1. Monogenea 2. Digeanea

Gill flukes Skin flukes

Adults

Encysted metacercaria

Gill

flukes

1. Dactylogyridae

2. Cichlidogyridae

Dactylogyrus vastator (D. vastator)

Cichilidogyrus tilapiae (C. tilapiae)

D. vastator

C. tilapiae

G. elegans

Haemorrhagic granuloma of Lernea copepode

Lernea cyprinicae

Anchor

2 egg sacs

Fish lice ( Argulus sp.) attached to fish skin

Ventral view of Fish Lice