Cestodes (The Taeenid tapeworms)

1. (4)
Turbellaria
Helminthes
Are eukaryotic multicellular parasites living in and feeding on
living hosts, receiving nourishment and protection while disrupting
their hosts' nutrient absorption, causing weakness and disease.
(2)
Cestodes (tapeworms)
Roundworms
(3)
Trematodes (flukes)
Flatworms (Platyhelminthes)
(1)
Nematodes
Helminthes
(3)
Monogeneans
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2. Cestodes
(The Taeenid tapeworms)
Dr. Souzan Eassa
Department of Microbiology
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3. The taeenid tapeworms known to
cause zoonotic infections in humans
are:
1. Taenia solium, pork tapeworm/ Hook tapeworm.
- Humans are the definitive hosts
- Pigs are the intermediate hosts.
- Causing cysticercosis
2. Taenia saginata, beef tapeworm/ Hookless tapeworm.
- Humans are the definitive hosts.
- Cattels and humans are the intermediate hosts.
- Intestinal taeniasis
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4. Differences between
T. solium and T. saginata
T. solium T. saginata
Size
Body length 2-4 meters
up to 10 meters
(70' worms have
been reported)
Scolex
4 suckers,
rostellum &
hooklets
4 suckers
Mature proglottid
Ovary
3 lobes 2 lobes
Testes 150-200 300- 400
Gravid proglottid:
Uterine branches
7-12 15-30
Life expectancy - 25 years or more 25 years or more
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5. T. saginata T.solium
D.H Human Human
I.H Cattle Swine and Human
Habitation
 Small intestine (Human)
 Tissue like brain, eye,
muscle, liver and lungs
etc. ( in Cattle)
 Small intestine (Human)
 Tissue like brain, eye,
muscle, liver and lungs etc. (in
Swine and humans)
Infective
stage
 Cysticercus bovis
larvae (Humans)
 Egg (Cattle)
 Cysticercus Cellulosae larvae
(Humans)
 Egg (Swine and humans)
Disease
 Taeniasis (Humans)
 Cysticercosis (Cattle
and humans)
 Taeniasis (Humans)
 Cysticercosis (Swine and humans)
Differences between
T. solium and T. saginata
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6. Egg, The eggs of Taenia saginata
and T. solium are identical.
The eggs are spherical, diameter
31 to 43 µm, with a thick radially
striated brown shell (embryophore).
Inside each shell is an
embryonated oncosphere with 6
hooklets.
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7. Life cycle of T. solium
1. final host: man.
2. Intermediate host: pig (or man).
3. Infective stage: cysticercus and egg.
4. Infective mode: eating raw bean-pork.
5. Site of inhabitation: adult in small intestine; cysticercus in
tissues.
6. Infective mode of cysticercosis: endogenous, exogenous
auto-infection and foreign source.
7. Life span: more than 25 years; cysticercus can survives
5-6 years in human body.
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8. Life cycle of T. saginata
1. final host: man.
2. Intermediate host: Cattle.
3. Infective stage: cysticercus.
4. Infective mode: eating raw beef.
5. Site of inhabitation: adult in small intestine.
7. Life span: more than 25 years.
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10. Life cycle of T. solium and T. saginata
 Infective eggs (from human feces) are ingested by the
intermediate host (cow or pig).
 The onchosphere hatches and penetrates the intestinal
mucosa of the intermediate host.
 Onchosphere delivered to various parts of body via the
circulatory or lymphatic systems. Most localize & encyst in
muscle.
 Infective stage - the encysted larva, called a cysticercus
develops within 2 months.
 Human infections take place when uncooked or undercooked
meat containing larvae is ingested.Souzan Eassa 10

11. Pathogenesis and Clinical Manifestations
1. Taeniasis: It is caused by the adult residing in small
intestine of the man.
The patient is usually no obvious symptom, only complaining
passing proglottides.
Some time the adult irritates the small intestine causing:
 Deprivation of nutrition
 Disfunction and discomforts of the intestine, such as
abdominal pain, anorexia, chronic indigestion,
emaciation, eosinophilia and etc. vomiting or diarrhea.
 Allergic reactions
 Appendicitis.
 Obstructions of the intestineSouzan Eassa 11

12. 2. Auto-infection, due to T.solium egg only; Pathogenic
factor: cysticercus cellulosae).
 Symptoms vary with site (the tissues and organs
involved) and intensity of infection (number of the
cysticerci).
 Clinical aspects: headache, dizziness, epilepsy,
blurred vision, subcutaneous nodule etc.
 Cysticercosis is divided into three types.
Pathogenesis and Clinical Manifestations
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13. The subcutaneous
nodules are usually found
in head, limbs, neck,
abdomen and back.
(1) Subcutaneous type:
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14. The cysticercus is usually
found in the vitreous body
or subretina. Visual
disturbance often occurs.
(2) Ocular type:
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15. (3) Brain type:
The symptoms are related
to the site of infection.
The patients may
manifest headache,
nausea, vomiting,
epilepsy, paralysis,
weakness in limbs,
diplopia, dizziness, mental
disorder. Epilepsy is the
most frequent symptoms
of brain cysticercosis.
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16. Brain type
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17. •
cysticercus in the tongue
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18. Diagnosis
• Taeniasis
Anal swab: to find egg at perianal region
Finding of gravid proglottids or eggs at the
perianal region by cellophane tape method.
Fecal exam: to find segment (species
identification).
• Cysticercosis
Biopsy (subcutaneous nodule).
X-ray/CT/MRI: cerebral cysticercosis.
• Serological tests
• Molecular Tests
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19. Treatment and Prevention
Treatment of Taeniasis:
Praziquantel.
Treatment of cysticercosis: Surgical
removal is required for ocular and superficial
cysticercoses.
(1) Health education.
(2) Avoid eating raw beef and pork.
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