Parasitology
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Helminthology
Platyhelminthes
(Flat worms)
Trematoda
(Flukes)
Ceastoda
(Tape worms)
Nematohelminthes
(Round worms)
Nematoda
Class Cestoda
(Tape Worms)
General Characters



Ribbon or tape shaped.
Adult worm composed of:a. Rounded scolex with appendages for
attachment (e.g. Suckers or hooked
rostella).
b. Neck (region of growth).
c. Strobillum (composed of 3- 4000
segments [proglottide]).
Length varies between 3mm-10m.
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
All cestodes are hermaphrodite
(Each segment contains male & female
reproductive system).

No body cavity.

No digestive tract.

No vascular system.
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 Habitat:
a. Adult worms live in small intestine
of their definitive hosts.
b. Larval stage found in intermediate
hosts tissues.
 Eggs are diagnostic stage
(Spherical, with shell embryonic
membranes for embryo protection;
the embryo [onchosphere] carries 6
elongated hooks [hexacanth])
 Replication is either by self-fertilization or by
cross fertilization.
 Usually the presence of adult worms in the
host intestine does not produce serious
symptoms, but severe and sometimes fatal
symptoms may occur due to presence of the
larval stage in the host tissues
(e.g. Tainea solium & Echinoccus granulosus).
Trematoda
2nd I.H
I.S.
Animal
Cercaria
1st I.H
(R)
D.H
D.S
Cestoda
I.S.
D.H
I.H.
D.S
In this course we study:
Taenia solium & Taenia saginata
Hymenolepis nana & Hymenolepis diminuta
Echinococcus granulosus.
Taenia solium
&
Taenia saginata
Taenia
solium
Taenia
saginata
Definition:-
Pork tape worm
Beef tape worm
Distribution:
World wide
World wide
Name:
• Depends
on the • Depends on the
access of pigs to access of cattle to
human feces and to human feces.
consumption of raw
& undercooked pork .
• More endemic in
Asia, South Africa
and East Europe.
Taenia solium Taenia saginata
Disease:
Habitat:
Definitive
host:
Intermediate
host:
Taenia
solium
Diagnostic stage:
Infective stage:
Mode of
infection:
Treatment:
Prevention:
Taenia
saginata
Taeniasis

Presence of the adult worm in small
intestine of human, symptoms are not
significant and thought to be psychic due to
vision of active proglottides in stool, these
symptoms may be abdominal discomfort
and intestinal irritation.
Cysticercosis
larvae development occurs in 2 months to
give
a fluid filled bladder with armed
scolex [a cysticercus].
 T. solium eggs
ingested by
human
hatch in the intestine, penetrate
mucosa & enter blood circulation
resident in liver, skeletal muscles, brain or
eye.


Usually no immune response as the larvae
are alive but when they die, the larvae are
classified after an inflammatory response and
symptoms begin to appear.
• In muscles:
Fever, swelling, atrophy & fibrosis.
• In brain:
Symptoms resembling brain tumors,
epilepsy, ataxic gait or mental
confusion (Neurocysticerosis).
• In eye orbit:
In anterior or posterior chambers affect eye
position, decrease visual acuity, retinal edema
and haemorrhage.
• Subcutaneous:
Palpated tumors.
Adult worm
This slide shows the gravid segment ; contains
male & female reproductive system).
[1]
Gravid segment
[2]
Mature segment
Differences between
T. solium &T. saginata
Scolex:
Taenia solium
Taenia saginata
Hooked with a
rostellum of double
hooked crown
Hooked scolex is
absent
Proglottides: In T. solium are shorter than those
of T. saginata
Uterine
branches of
gravid
segments:
Are lower in number in T. solium
than that of T.saginata
Hooked
scolex
Sucker
[1]
[2]
[1]
[2]
T. solium has 7 to 13 branches.
T. saginata has 15 to 20 branches.
?
Diagnostic Stage
•
Taenia egg
Taenia saginata & Taenia solium.
* Appears in stool.
* Egg contains oncosphere embryo
with 6
hooklets (hexacanth
embryo).