Trematodes are endoparasites of invertebrate,
belonging to the class of platyheminths (flat worm) and are commonly referred
to as “blood flukes”. The fluke (flat) is named for the characteristic avoid or
flattened body found in most adult worms and a more cylindrical body plan. The
name trematode (Gr.trema, a hole) comes from the muscular sucker containing a
mouth (hole) at the fluke’s anterior end. Trematodes that parasitize man are
grouped into the following.
belonging to the class of platyheminths (flat worm) and are commonly referred
to as “blood flukes”. The fluke (flat) is named for the characteristic avoid or
flattened body found in most adult worms and a more cylindrical body plan. The
name trematode (Gr.trema, a hole) comes from the muscular sucker containing a
mouth (hole) at the fluke’s anterior end. Trematodes that parasitize man are
grouped into the following.
Liver flukes – e.g fasciola hepatica, opisthorchis
sinensis etc
sinensis etc
Lung flukes – e.g paragonimus, wester man,
paragoniumus kalkotic
paragoniumus kalkotic
Intestinal flukes – e.g
Heterophyyes heterophyes, fasciolopsis busk, metagonimus yokogawa, schisstosoma
japonicum, schistosoma mensoni
Heterophyyes heterophyes, fasciolopsis busk, metagonimus yokogawa, schisstosoma
japonicum, schistosoma mensoni
Urinary/renal flukes e.g
schistosoma haematobium.
schistosoma haematobium.
Flukes have digestive, excretory, muscular, and
reproductive systems, but lack circulatory and respiratory systems. Except in
the blood flukes both male and female reproductive systems occur in the same
individual and occupy a major portion of the body. The trematodes life cycles
are closely adapted to agricultural practices such as flood irrigating and
using raw sewage as fertilizer. In human fluke cycles, animals such as snails
or fish are usually the intermediate hosts and humans are the definitive hosts.
reproductive systems, but lack circulatory and respiratory systems. Except in
the blood flukes both male and female reproductive systems occur in the same
individual and occupy a major portion of the body. The trematodes life cycles
are closely adapted to agricultural practices such as flood irrigating and
using raw sewage as fertilizer. In human fluke cycles, animals such as snails
or fish are usually the intermediate hosts and humans are the definitive hosts.
Representative: Medical Important Tremalodes
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Organism Binomial
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Disease
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Host Range
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Location in the body
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Geographical distribution
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Schistosoma mansion
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Schistosomiasis
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Humans
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Blood vessel of intestine
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Africa south America etc
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Schistosoma japonicum
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Schistosomiasis
|
Humans
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Blood vessel of intestine
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Japan, china philipines
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Schistosoma haematobium
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Schistosomiasis
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Humans monkeys
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Blood vessels urinary bladder
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Mainly Africa and Madagascar
|
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Paragonimus westermani
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Paragonimiasis
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Humans cats
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Lungs
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Far East, Nigeria, America, congo etc
|
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Heterophyes heterophyes
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Heterophyiasis
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Humans, cats dogs
|
Small intestine
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Near East far East
|
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Fasciolopsis buski
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Fasciolopsiasis
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Humans, pigs
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Small intestine
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Orient
|
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Fasciola hepatica (sheep liver fluke
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Fascioliasis
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Human, sheep goats
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Liver bile ducts
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Sheep-raising region
|
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opisthorchis (clonorechis) sinensis (Chinese
liver fluke) |
Clonorchiasis
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Humans dogs, cat
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Liver bile ducts
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China, japan korea, etc.
|
General characteristic
1.
Morphology: Trematodes are commonly
referred to as the blood/intestine flukes. They are leef-shaped and most
species possess external cuticle which maybe smooth or covered with scales,
spines, tubercles or ridges. They are unsegmented and non-elongated muscle.
Layer under the cuticles helps to propel worm. The interior cavity of the worm
consists of a mass of parachyme cells forming a net work of supportive organs.
They also like the nematodes possess all necessary organs required fro the
effective development such as the alimentary respiratory, excretory and
reproductive system etc. the worm possess some muscular structure called
suckers. They are mainly used as organs of attachment to the body. They are
found surrounding various openings on the body. Majority of trematodes have two
(2) suckers (i.e an oral and ventral sucker but the species heterophye heterophyes
has an additional genital sucker).
Morphology: Trematodes are commonly
referred to as the blood/intestine flukes. They are leef-shaped and most
species possess external cuticle which maybe smooth or covered with scales,
spines, tubercles or ridges. They are unsegmented and non-elongated muscle.
Layer under the cuticles helps to propel worm. The interior cavity of the worm
consists of a mass of parachyme cells forming a net work of supportive organs.
They also like the nematodes possess all necessary organs required fro the
effective development such as the alimentary respiratory, excretory and
reproductive system etc. the worm possess some muscular structure called
suckers. They are mainly used as organs of attachment to the body. They are
found surrounding various openings on the body. Majority of trematodes have two
(2) suckers (i.e an oral and ventral sucker but the species heterophye heterophyes
has an additional genital sucker).
2.
Alimentary system: This consists of an
anteriorly placed mouth leading to the oesophagus that is surrounding by a
muscular sucking pharynx. After the pharynx, the intestine bifurcates to form
the caeca – which maybe straight or undulating long or short but usually ends
blindly without an anus.
Alimentary system: This consists of an
anteriorly placed mouth leading to the oesophagus that is surrounding by a
muscular sucking pharynx. After the pharynx, the intestine bifurcates to form
the caeca – which maybe straight or undulating long or short but usually ends
blindly without an anus.
3.
Nutritionally: The worm ingests
semi-liquid or viscious food such as intestinal content, mucus and bile. They
also feed largely on bacteria, mucus and food detrite
Nutritionally: The worm ingests
semi-liquid or viscious food such as intestinal content, mucus and bile. They
also feed largely on bacteria, mucus and food detrite
4.
Excretion system: is made up of minute
ciliated “flame” cells. So named because the cilia of the cells exhibits a
flicking movement which reminds one of a candle flame. The cells are distributed
in the entire body of the worm in large numbers and are connected with
capillaries which unite to form a larger vessel that finally discharges at a
single posterior excretory pore or bladder.
Excretion system: is made up of minute
ciliated “flame” cells. So named because the cilia of the cells exhibits a
flicking movement which reminds one of a candle flame. The cells are distributed
in the entire body of the worm in large numbers and are connected with
capillaries which unite to form a larger vessel that finally discharges at a
single posterior excretory pore or bladder.
5.
Reproductive system: with the exception of the
schisstemes. All other tremetodes are harmophrodites and the geniatl organs are
located between the bifurcate intestine. The male organs consist of two testes
the vasadefferentia pera. It may sometimes terminate in a structure called the
cirrus which maybe enclosed in a cirrus pauch. The female organs consist of a
single ovary from which the oviduct arises. It is divided into two, one branch
forming a large receptaculum seminus which ends blindly the other forms the
main oviduct which receive the duct from the vetelline and shellglands. The
junction formed by the oviduct and the viteline and shell gland is known as the
fertilization canal and the interior part of the canal forms the uteries, which
received the spermatozoa and discharges the eggs at the common genital pore.
There is no vigina.
Reproductive system: with the exception of the
schisstemes. All other tremetodes are harmophrodites and the geniatl organs are
located between the bifurcate intestine. The male organs consist of two testes
the vasadefferentia pera. It may sometimes terminate in a structure called the
cirrus which maybe enclosed in a cirrus pauch. The female organs consist of a
single ovary from which the oviduct arises. It is divided into two, one branch
forming a large receptaculum seminus which ends blindly the other forms the
main oviduct which receive the duct from the vetelline and shellglands. The
junction formed by the oviduct and the viteline and shell gland is known as the
fertilization canal and the interior part of the canal forms the uteries, which
received the spermatozoa and discharges the eggs at the common genital pore.
There is no vigina.
Development: Trematodes are oviparous (i.e egg laying worms) produces operculated
eggs and pess through four larva stages, except schistosomes which have
non-operculated (without lid) eggs and only three larva stages. The eggs can be
found in sputum
