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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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