Tissue Cestodes Concise Pharmacy

8/7/2019 Tissue Cestodes Concise Pharmacy

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TISSUE CESTODES

Dr Mohiedden M Abdul-Fattah


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Final host:

Intermediate host(IH):

Paratenic IH

Reservoir Host: Prepatent period

Auto infection:

Non-patent Infection


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Tissue cestodes: all are larvae.

The larvae are either

Solid in pseudophyllidea as

1. sparganum of (Spirometra) mansonoides, or

Cystic in cyclophyllidea as

2. Cysticecus cellulosae of T.solium,

3. Coenurus of T.multiceps, and

4. hydatid cyst of Echinocccus granulosus5. Alveolar hydatid cyst of E.multilocularis.


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Sparganum


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1) Ingestion of egg or larva never gives adult in man

2A) Ingestion of eggs never gives adult in man but ingestion oflarva can

2B & 2C) ingestion of egg or larva never gives adult in man


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Man is infected by larval cestodiases when he

ingests the eggs

The only exception is the infection by sparganum

It is caused by ingestion of procecoid in cyclops or

plerocercoid (sparganum) larvae in fish or frogs.

The cyclophylidean larval cestodes are cystic in

vertebrate intermediate hosts.

Pseudophyllidean larval cetodes are worm like in

invertebrate IH (Cyclops) and/or vertebrate host.


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Sparganosis Definition: infection of human tissues with thesparganum larvae ofSpirometra mansonoides


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I. Biology


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I. BIOLOGY Two species:

1. Spirometra. mansonoides

2. S. proliferum (proliferative sparganosis); the larvaproliferate into surrounding tissue by lateral budding.

Man never acts as final host, but dogs and cats do.

Man acts only as dead end paratenic IH Host. Habitat of larva in man: subcutaneous tissue,muscles, eye and CNS.

Exit stage from man: none, but diagnosis made

when sparganum is surgically recovered. Exit stage from dogs and cats: Immature eggs

passed in faeces (in water)


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II. Epidemiology Distribution: southeastern Asia and east Africa.

Transmission:

Intermediate hosts: Cyclops is 1st IH and

Frogs, snakes, birds and mammals are 2nd IH.

Resevoirs: Birds and other mammals.

Infective stages: procercoid and sparganum. Mode of infection:

1. ingestion Cyclops containing procercoid ofS.mansonoides

2. ingestion of sparganum in flesh of frogs, snakes orbirds.

3. cutaneous exposure using the uncooked meat of theseinfected animals as poultice on an inflamed skin or eye.


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III. Host-parasite relationship Pathogenesis:

1. Depends on final location of migrating sparganum

2. Spargana may locate anywhere.

3. subcutaneous tissue, breast, orbit, urinary tract,pleural cavity, lungs, abdominal viscera and CNS

Clinical picture:1. The migration in subcutaneous tissues is usually

painless,

2. but nodules on the chest and legs may be painful.

3. in the brain: headache, fits may occur

4. In the orbit: conjunctivitis and periorbital oedema.

5. In the inner ear: vertigo or deafness may occur.


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IV. Diagnosis:

1. Excision and identification of sparganum in

the lesion. ~5 cm white glistening worm.

2. Imaging: CT or MRI

3. Serotesting for specific antibodies (ELISA)


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ophtlamoscopy


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V. Treatment

1. Spargana are resistant to praziquanteland mebendazole.

Currently there is no recommended drug

therapy for sparganosis.2. Surgical removal of the complete

sparganum is the best treatment.

3. 40% ethanol injection with procaine to killthe larva in situafter which they are

allowed to be absorbed.


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VI. Control

Avoid sources of infection:

1. Cyclops: Boiling or filtering of water in

endemic areas.

2. Frogs and birds: Do not use their flesh

as poultices.

3. Frogs and birds: Do not eat theirundercooked meat.


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CysticercosisInfection of human tissues by

cysticercus cellulosae; larva of Taenia

solium.


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III. Host parasite relationshipA.Pathogenesis

As the larva begin to die a pronounced cellular reaction occurs,

followed by fibrosis, necrosis of the capsuleand calcification of the larva in all tissuesExcept.

In the eye, ventricles of the brain, and in thesubarachnoid space.

There is no fibrosis, but hydrocephalus occur When cysts exist in vital organs; acute andsometimes fatal sequences develop.

The location in the eye may be sub-choroidal,

sub-retinal, and intra-vitreous.


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III. Host parasite relationshipB. Clinical picture:

Ocular cysticercosis:1. visual impairment due to shadows cast by thelarva in front of retina.

2. If not removed, it will produce uveitis, retinitis,retinal detachment and blindness.

Cerebral cysticercosis:1. Adult onset epileptic fit.

2. Obstructive hydrocephalus.

3. Meningitis

4. Behavioral disturbance. Intermuscular nodules.

Subcutaneous nodules.


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Subcutaneous nodules Intermuscular nodules


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IV. Diagnosis

Detection of egg or gravid segment of Taenia

solium in stool may suggest auto-infection. Imaging:

1.Plain x-ray.

2.CT and MRI: most effective in cerebral cysticercosis. Detect specific antibodies in serum or CSF:

1.ELISA using crude antigen extracted from the wholecyst or its fluid, or using purified antigen fractions.

2. immunoblot Biopsy


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V. Treatment

Recommend combined antiparasitic andanti-inflammatory therapy.

Praziquantel: PO for 15-30 days,or

Albendazole: PO for 30 ds. Cortisone to to reduce inflammatory

reaction due to dying cysticerci.

Surgical excision for ocular cysticercosis,muscular and SC cysticerci

CNS cases; non responders to drug.


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VI. Prevention and Control

Prevent infection of man from pigsThorough cooking or freezing of pork.

Prevent infection of man from man

A. Prompt treatment of intestinal taeniasis solium.

B. Sanitary disposal of human excreta

C. Personal hygiene.

D. Proper washing of fruits and vegetable

Prevent auto infection of man

1. Avoid emetic drugs


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Human tissue cestodiases


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CoenurosisInfection of human tissue by Coenurus cerebralis;

Larva of Taenia multiceps


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I. Biology Final Hosts are dog, wolf and

fox : They harbor the Adulttapeworm that resemblesTaenia .in their intestine.

Man: harbors the cystic larvaonly and acts only as dead endintermediate host.

Habitat in man: Cysts exist in allorgans but more in eyes andbrains.

Exit stage: None, but cyst canbe excised surgically.

Exit stage from final hosts:Taenia like eggs

Cyst has

multiple

scolices, but

no daughter

cysts

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Tissue Cestodes Concise Pharmacy