Metazoan diseases Phylum Platyhelminthes commonly known as the

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Metazoan diseases

Metazoan diseases

Phylum Platyhelminthes • commonly known as the flatworms • dorsoventrally flattened, bilaterally symmetrical and

Phylum Platyhelminthes • commonly known as the flatworms • dorsoventrally flattened, bilaterally symmetrical and acoelomate • They usually lack an anus and specialized skeletal, circulatory and respiratory systems. • The majority of Platyhelminthes are monoecious, i. e. both male and female reproductive systems occur in the same individual.

Class Monogenea • ectoparasitic animals with no intermediate hosts involved in the life cycle.

Class Monogenea • ectoparasitic animals with no intermediate hosts involved in the life cycle. • They are about 3 cm in length. • possess a posterior organ of attachment known as the haptor, armed with hooks and or clamps or suckers. • they usually have some form of attachment organ at the anterior end.

Subclass : Monopisthocotylea • The haptor is a single unit with one or two

Subclass : Monopisthocotylea • The haptor is a single unit with one or two pairs of large hooks (anchors) and 12 to 16 lateral hooklets. • The anterior attachment organ is often glandular. • The mouth is not surrounded by the sucker. Eyespots are frequently present anteriorly. • Comprises of two families Gyrodacrylidae and Dactylogyridae.

Subclass : Polyopisthocotylea • In this group the haptor is well developed and bears

Subclass : Polyopisthocotylea • In this group the haptor is well developed and bears clamps and suckers. • Anchors may be present. • An oral sucker may be present anteriorly.

Dactylogyrus and Gyrodactylus • Symptoms: cloudiness of skin, grey white colour, focal haemorrhages on

Dactylogyrus and Gyrodactylus • Symptoms: cloudiness of skin, grey white colour, focal haemorrhages on skin. The infection is ectoparasitic and can cause considerable damage to the host when present in high numbers. • Opisthaptor-a multiple hooked attachment organ. Treatment • 3 to 5 minute saltwater bath (30 -35 ppt). • Glacial acetic acid or hydrogen peroxide dips will also kill these parasites. • Praziquantel baths have also proved to be effective in killing some monogenean worms

Class Digenea • endoparasitic animals • Both adult and larval metacercarial stages are found

Class Digenea • endoparasitic animals • Both adult and larval metacercarial stages are found in fish • The majority of digeneans have two suckers on their body surface, one at the anterior end and one ventrally located • Hermaphrodite in nature • Families - Sanguinicolidae, Bucephalidae and Allocreadiidae.

 Class Cestoda • A scolex (attachment organ) present at the anterior end. •

Class Cestoda • A scolex (attachment organ) present at the anterior end. • The adult worms are usually white in colour and may be very elongated. • parasitic in the intestine of the host • The Cestoda includes the orders Proteocephalidea, Pseudophyllidea, Tetraphyllidea, trypanorhychidea and Caryophyllidea.

Phylum : Aschelminthes Bilaterally symmetrical pseudocoelomate animals. Class Nematoda • elongate worms with a

Phylum : Aschelminthes Bilaterally symmetrical pseudocoelomate animals. Class Nematoda • elongate worms with a cylindrical body tapering at both ends. • The mouth is located anteriorly. • The gut is clearly divided into an oesophagus and an intestine. • The sexes are separate. • The Nematoda includes the orders Trichuridea, Ascariddea, Spiruridea, Filariidea and Diocrophymidea.

Phylum Acanthocephala • Mostly elongate cylindrical worms armed with an anterior retractile proboscis carrying

Phylum Acanthocephala • Mostly elongate cylindrical worms armed with an anterior retractile proboscis carrying hooks. • Gut absent, sexes are separate. • At least one intermediate host is required in the life cycle.

Phylum Mollusca • The larvae of freshwater bivalve molluscs are often found attached to

Phylum Mollusca • The larvae of freshwater bivalve molluscs are often found attached to the gills and outer surfaces of fish. • The larvae have this bivalve shells often with little hooks on their inner edge.

Phylum Arthropoda: • Bilaterally symmetrical animals with segmented bodies bearing jointed appendages. • The

Phylum Arthropoda: • Bilaterally symmetrical animals with segmented bodies bearing jointed appendages. • The body in covered with a rigid or semi-rigid chitinoid exoskeleton. Subclass Branchiura • Body flattened dorsoventrally. • Two pairs of antennae and a preoral proboscis are present. • The second maxillae usually form prehensile suckers, eg. Argulus.

Argulus • important ectoparasite infecting fish. • Commonly called the "Fish Louse", these are

Argulus • important ectoparasite infecting fish. • Commonly called the "Fish Louse", these are flattened creatures with a very distinctive shape and appearance. • They move about the skin of a fish very effectively and camouflage themselves well on the host. • They suck body fluids from the fish via a sharp stylet that actually injects a small amount of toxin into the fish. • Argulus also possesses a life cycle with pelagic larval stages so the entire aquarium system may have to be treated with organophosphates to control the disease

Subclass Copepoda. • copepods found on fish are mostly ectoparasitic. • They display a

Subclass Copepoda. • copepods found on fish are mostly ectoparasitic. • They display a great range of body form, ranging from those types such as • Ergasilus -unfused abdominal segments and • Lernea in which the body segments are fused together and many of the appendages are missing or highly modified. • The Copepoda includes the orders Cyclopidea, Caligidea and Lernaeopodidea.

Lernea • infects large scaled freshwater tropical and temperate species of fish • possesses

Lernea • infects large scaled freshwater tropical and temperate species of fish • possesses a life cycle that includes microscopic pelagic larval stages • easily visible to the naked eye and may be more than 2 cm in length. • Infected fish scrapes against objects, whitish-green threads hang out of the fish skin with an inflamed area at point of attachment. treatment • Organophosphates and glacial acetic acid dips • 10 to 30 minute bath in 10 mg/l of potassium permanganate.

Phylum Annelida Segmentaed, coelomate worms with a muscular body. Class: - Hirudinea • The

Phylum Annelida Segmentaed, coelomate worms with a muscular body. Class: - Hirudinea • The leeches have a segmented body with anterior and posterior suckers. • There may be eyespots anteriorly. • The body may be round or somewhat dorsoventrally flattened. • Leeches are ectoparasitic on fish. • Families Piscicolidae and Glossiphorniidae.

Phylum Chordata Order Petromyzontia Family petromyzontidae • The Lampreys are eel-like, mostly freshwater or

Phylum Chordata Order Petromyzontia Family petromyzontidae • The Lampreys are eel-like, mostly freshwater or anadromous, jawless fishes. • They have a round suctrorial disc-like mouth with horny teeth. • The single nostril is dorsally situated. • The fins have no rays. • They are sanguinivorous in nature