Cestoda Tapeworm

7/29/2019 Cestoda Tapeworm

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Introduction of Cestodes

(Tapeworms)

Phylum Platyhelminthes

Class CestodaOrder Pseudophyllidea

Order Cyclophyllidea


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Morphology

Flat, segmented body with various length

(several mm ~ several meters)

3 regions of worm body:

Scolex: suckers, hooklets, grooves

Neck: germinal portion

Strobila: immature, mature, gravid proglottids

(segments)


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Monoecious (each segment): reproductive

system highly developed

Digestive system degenerated

All species are parasitic


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Tapeworms


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Taenia soliumPork tapeworm / Hook tapeworm

/

Taenia saginata

Beef tapeworm / Hookless tapeworm/


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Morphology

T.saginata T.solium

Size 4-8 m 2-4 m

Scolex 4 suckers4 suckers,

rostellum & hooklets

Mature proglottid

Ovary2 lobes 3 lobes

Testes 300-400 150-200

Gravid proglottid:

Uterine branches15-30 7-12


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Taenia spp. adult worm

The chain of proglottids is called the strobila, and may be composed of

over 1.000 proglottids.T.saginatamay measure 9 m, whereasT.soliummay reach 6 m.


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The beef tapeworm(Living specimen)


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The scolex ofT. solium

hooklets

rostullum

suckers


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The scolex ofT. saginata


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Taenia saginata, fresh specimen


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Gravid proglottid ofT. solium


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Gravid proglottid ofT. saginata


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Larva

Cysticercus bovis

Cysticercus cellulosae

Ovoid, cystic, size = a bean

Invaginated scolex and neck


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T.solium: cysticercus cellulosae with invaginated scolex


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Egg

Indistinguishable in two species

Ovoid

< Ascarid egg

Radically striated embryophore

Content: hexocanth embryo (oncosphere: 6hooklets)


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Taenia spp. eggCan not differentiateT. saginata fromT. solium


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Taenia spp. egg


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Life Cycle

Definitive host

Human being; No reservoir host

Discharged stage

Eggs or gravid proglottids in feces


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Life cycle ofTaenia saginata


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Life cycle ofTaenia solium


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T.saginata T.solium

D.H Human Human Human

I.H Cattle Swine Human

Habitation Small intestine Small intestineTissue(brain, eye,

skin etc.)

Infective stage Cysticercus bovis CysticercusCellulosae

Egg

Disease Taeniasis Taeniasis Cysticercosis


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Pathogenesis

Taeniasis ( Infected by eating cysticerus; Pathogenicfactor: adult worm)

Deprivation of nutritionDisfunction of the intestine: vomiting or diarrhea

Allergic reactions

AppendicitisObstructions of the intestine


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Cysticercosis (Intrinsic or extrinsic auto-infection;

Cross infection due to T.solium egg only; Pathogenic

factor: cysticercus cellulosae)

Symptoms vary with site & intensity of

infection

Clinical aspects: headache, dizziness, epilepsy,

blurred vision, subcutaneous nodule etc


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Diagnosis

Taeniasis

Anal swab: to find egg at perianal region

Fecal exam: to find segment (speciesidentification)

Cysticercosis

Biopsy (subcutaneous nodule)

X-ray/CT/MRI: cerebral cysticercosis

Ophthalmoscopy: ophthalmic cysticercosis


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Epidemic factors

Egg or gravid proglottid contamination of grass

and soilMethod of raising domestic animals

Unhygienic dinning habit of eating raw or

undercooked meat


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Control

Treatment

Paziquantel

Areca nut + pumpkin seed+ purge

Scientific cattle and pig raising

Avoid to consume raw meat

Meat inspection


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Morphology

Adult worm

3-6 mm long with 4 segments

Scolex & cervical portion (2 rows of 28-40hooklets and 4 suckers)

Immature, mature, gravid segments

EggSimilar to the Taenia egg


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Adult ofEchinococcus granulosus


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Hydatid sand

The protoscoleces generally settle down at the

bottom of the cyst and are known as hydatidsand.


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Protoscoleces with double row hooklets and calcareous corpuscles


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Hydatid sand


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Life Cycle

Adult worm

In the small intestine of the dog and other

carnivores

Larva (hydatid cyst)

In the tissue of human being, sheep, horse, pig,

etc.


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Infective stage: egg

Infective route: mouth Location: liver, lung, brain, eye, kidney,

muscles, bone and heart

Zoonotic parasite


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Pathogenesis

Echinicoccosis, Hydatidosis

Depend on the location and the number of

hydatid cysts

Pressure: liver, pulmonary, etc

Allergy: anaphylactic shock

Regeneration: secondary infection


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Epidemiology

Distribution

Forest type (human are seldom involved)

Wolf-moose/reindeer

Dingo-wallaby

Animal raising type (human are involved) Dog-sheep/cattle/pig


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Endemic factors

High resistant egg

Intimate contact between dog, animals and man

in local district

Contamination of the feces by infected dogs

Improper the viscera disposition


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Treatment and Control

Surgical removal of the cyst

Long-term Mebendazole therapy

40 mg/kg/day 1-6 months

Personal protection

Reasonable disposition of the viscera from

infected animals Treatment of sheep dogs periodically


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Documents

Cestoda Tapeworm