CESTODES Taenia saginata

- aka. beef tapeworm

Cestodes (Tapeworm) - transmitted from cows/cattle to man
-include multiple species of flatworms that can reside - Habitat: SI
in the human gastrointestinal tract (GI). - IH: Cattle
 Taenia saginata - DH: Humans
 Taenia solium - IS: Cysticercus bovis (2 months)
 Hymenolepis nana - DS: Egg or gravid proglottids
 Hymenolepis diminuta - MOT: Ingestion of raw or undercooked infected
 Dipylidium caninum meat
 Diphyllobothrium latum - Treatment: Praziquantel
 Echinococcus granulosus
Morphology:
Order Egg: hexacanth, spherical in shape, Egg has a thick
Pseudophyllidea – D. latum striated wall; brownish in color
Cyclophyllidea Scolex: Cuboidal, w/ 4 acetabula/suckers, no
hooklets and no rostellum
a.Species which requires a vertebrate intermediate Mature segment w/ ovary & testes.
host Gravid segment has 15 or more uterine branches.
b.Species which requires invertebrate intermediate
host
c. Species which may or may not require an
intermediate host

General Characteristics
- Flat, segmented, ribbon like bodies, are
whitish/creamy and yellowish in color and are
bilateral symmetrical.
- Are Hermaphroditic –
- Do not have a digestive tract
- they can be heteroxenous (more than one host is
parasitized) and homoxenous (only one host is
parasitized) as to host requirement
- Adult tapeworms are found in SI while larva stage
is encysted in tissues of Intermediate host.

Parts of the Tapeworm Body

1.Scolex – organ for attachment
2.Neck – region of growth
3.Segments/Proglottids – 3 types: immature, mature
and gravid/ripe

Pathogenesis and Clinical Manifestations

- Taeniasis – the passage of proglottids or segments
in the stool.
- mild irritation at the site of attachment
Taenia solium
- aka. pork tapeworm
- Habitat: SI
- IH: Man, Pig
- DH: Human
- IS: embryonated egg/cysticercus cellulosae
- DS: Egg or gravid proglottids
- MOT: Fecal – route / Ingestion of raw or
undercooked infected meat (measly pork)

Morphology:
Egg: hexacanth, more spherical than T. saginata, has
rostellum w/ 25-30 hooklets (2 rows)
Strobila/Proglottid: 7 to 15 branches
(dendritic/fingerlike)
Mature segment w/ ovary & testes & an accessory
lobe in the ovary
Gravid segment has 13 or less uterine branches w/
genital pore

Differences T. Saginata T. solium

CN: beef tapeworm pork tapeworm
IH: Cattle Pig / Man
w/ rostellar hooks
None, no warmed w/ 2 rows
Scolex
rostellar hooks of large and small
hooklets
Length 25 m 7m
# of
1000-2000 <1000
proglottids
15-20 lateral 7-13 lateral
Gravid
branches (tree branches
proglottids
like) (fingerlike)
Sperical, striated inside an embryo w/ 6
Eggs
hooklets
Larva
Cysticercus
Infective Cysticercus bovis
cellulosae
Stage
Taeniasis Taeniasis solium,
Pathogenesis
saginata cysticercosis
INFECTIVE STAGES TREATMENT
1. T. solium = cysticercus cellulosae. 1. Praziquantel = drug of choice.
2. T. saginata = cysticercus bovis. 2. Bithionol
 Cysticercus contains the larva of the adult taenia &  Expel the worms completely & get rid of the source
it is usually lodged in the skeletal muscles of the of eggs & gravid segments.
pork or beef.  Objective of treatment is not only to expel the
 Ingested cysticercus is acted upon by the gastric segments or proglottids but more importantly, to
juices & the scolex inside the cysticercus evaginates. remove the scolex of taenia.
 The scolex or head then attaches to the walls of the
SI & begin to grow segments. LABORATORY DIAGNOSIS OF TAENIASIS
 Within 3 months, the taenia is fully grown with 1. Feces
immature, mature, & gravid segments. 2. Perianal region (Cellophane Scotch
 The gravid segments contain thousands of eggs & Tape)
these segments normally separate from the main a. Eggs
body. b. Structure of proglottids
 Once separated, these gravid segments are capable
of amoeboid movement where they move on their Hymenolepis nana
own & can pass thru the anus of the host. - aka. dwarf tapeworm
 These segments will then reach the outside - HOMOXENOUS
environment where the eggs will get into the IH - cyclophyllidean tapeworm; the smallest tapeworm
(cattle & swine) which feed on grass, food, or water - Only tapeworm to complete its entire life cycle in a
contaminated with excreta. single host
 Eggs inside the IH will hatch & develop into - Eggs are infective when passed with stool, but
cysticercus/cysticerci in the muscles & other organs. cannot survive more than about 10 days outside the
 Cysticercosis is now the infection with the larval body.
form of taenia which is common among the animal - Habitat: SI DH: Humans, mice, rats
IH. - IS and DS: Eggs (embryonated)
- MOT: Ingestion of embryonated egg from
CONSEQUENCES OF TAENIASIS contaminated food, water, or hands
 Most taeniasis cases are asymptomatic because - Treatment: Praziquantel, Nitazoxanide (alternative)
most infections are single-worm infections making
the symptoms vague & nonspecific if at all present. Morphology:
 Most common complaint is the passing out of gravid Egg: has bipolar thickenings and polar filaments;
segments. spherical/subspherical, colorless/clay-colored
 Acute appendicitis if the segment is trapped in the Scolex: Retractable rostellum w/ 20-30 Y shaped
appendiceal hooklets
 lumen. Strobila: 175 to 220 segments, 3 testes and 1 ovary
 Acute pancreatitis if the segment blocks the duct of
Wirsung.
 Cysticercosis with common sites in the skeletal
muscles, lungs, liver, & brain (neurocysticercosis).

PREVENTION AND CONTROL

1. Treatment of identified cases.
2. Proper excreta disposal.
3. Proper care of cows & pigs.
4. Screening of “measly pork” or “cysticerci-laden
beef” in slaughterhouses.
5. Proper cooking of pork or beef (560C is enough to
kill cysticercus).
6. Deep freezing of meat (-50C or lower definitely kills
infective stages).
7. Health education.
Hymenolepis diminuta
- aka. rat tapeworm
- requires IH
- can cause hymenolepiasis
- Habitat: SI
- IH: fleas, beetles, cockroaches, mealworms, earwigs
- DH: Humans, mice, rats
- IS: Cysticerci / cysticercoid larvae
- DS: Eggs / proglottids
- MOT: Ingestion of cysticerci in body cavity of insect
- Treatment: Praziquantel

Morphology: Non-operculated w/ embryo

Egg: circular, bile stained, fan like arrangement of
hooks, presences of bipolar thickening, NO POLAR
FILAMENTS and w/ intralaminal layers
Scolex: unarmed rostellum
Strobila: unilateral genital pores (larger than H.
nana)
Dipylidium caninum Diphyllobothrium latum
- aka. flea tapeworm / cucumber tapeworm / double- - aka. fish tapeworm / broad tapeworm
pored tapeworm - Diphyllobothriasis - the intestinal infection w/ adult
- very common intestinal parasite of dogs and cats worm
worldwide - causes tapeworm anemia, hyperchromic,
- Dipylidiasis in humans is accidental and more megaloblastic anemia
common in children than in adults - Habitat: SI
- Habitat: SI - IH: 1st – copepods (cyclops); 2nd – fresh water fish
- IH: Ctenocephalides canis, Ctenocephalides felis, (salmon), perch, trout, salmon, pike
Trichodectes canis, Pulex irritans - DH: Human, dog and cats, fish-eating mammals,
- DH: Dog and cats birds
- IS: Cercocystis / cysticercoid larva - PH: Carnivorous fish
- DS: Proglottids - IS: Plerocercoid larva
- MOT: Ingestion of fleas containing cysticercoid / - DS: Unembryonated egg
infected flea - MOT: Ingestion of raw or undercooked infected fish
- Treatment: Praziquantel - Treatment: Praziquantel

Morphology: Morphology:
Egg: found in packets/embryonic membrane (8-15 Egg: yellowish brown, thick shell, operculated,
eggs) opposite is small knob like opening
Scolex: globular, has 4 suckers and potrusible Scolex: spatulate/spoon shaped/almond shaped w/
rostellum, rose thorn shaped hooks 2 bothria/sucking grooves
Strobila: pumpkin seed shaped enclosing egg Strobila: longer width than its length, presence of
packets, melon seed/rice grain shaped (mature and dark, rosette like coiled uterus
gravid) Larval stages: coracidium > procercoid >
plerocercoid
Echinococcus granulosus
- aka. hydatid worm / hyper tapeworm / dog
tapeworm
- causes Echinococcosis; hydatid disease; hydatid cyst
- Habitat: SI
- IH: Sheep, goat, swine
- DH: dog, wolves, jackals, coyotes, foxes
- AH: Man
- IS: Embryonated egg
- DS: Hydatid cyst
- MOT: Ingestion of dog/canine stools filled w/
embryonated eggs
- Treatment:
 Surgical resection
 Albendazole
 Mebendazole
 Percutaneous aspiration, injection,
reaspiration (PAIR) technique

Morphology:
Egg: resembles Taenia specie
Hydatic cyst: outer laminated hyaline layer and
inner germinal layer
Scolex: armed scolex, 30-36 hooks and 4 acetabula
Strobila: widest proglottid
RECALLS:
A. Scolex/Head
1.With spatulate/spoon shaped/almond shaped
scolex
2.With globular scolex without hooks
3.With globular scolex with hooks
4.With Y-shaped hooks

B. Segments/Proglottids
1.With 3rd ovary (Accessory Ovarian lobe)
2.With Bilateral Genital Pores

C. Gravid/Ripe proglottid
1.Broader than long with rosette uterus
2.Elongated uterus with lateral uterine branches,
longer than broad and has cylindrical trunks (8
to 12/15 branches)
3.Elongated uterus with lateral uterine branches,
longer than broad and has cylindrical trunks (15
to 30 branches)
4.Broader than long, sac-like or saccular uterus
5.Longer than broad and loosely twisted uterus
6.Vase shaped or pumpkin seed shaped segments

1.Longest cestode as to length

2.Shortest as to length
3.Shortest cestode that can infect man in its adult
stage
4.Causes Vit.B12 deficiency anemia
5.Ingestion of Plerocercoid
6.Ingestion of Procercoid
7.Ingestion of Cysticercus larva
8.Ingestion of T.solium eggs only