- Cestodes are tapeworm parasites that infect the intestines or tissues of hosts. They are classified as either pseudophyllidean or cyclophyllidean based on morphology and life cycle. - Pseudophyllidean cestodes have unbranched uteri and operculated eggs, while cyclophyllidean cestodes have branched uteri, non-operculated eggs, and larvae that form cysts or bladders. - Common cyclophyllidean cestodes include Taenia saginata, T. solium, and Echinococcus granulosus, which infect humans and require one or two intermediate hosts to complete their life cycles.

1. CESTODES
- Dr. ANKUR KUMAR

2. TOPICS for discussion-
• INTRODUCTION
• CLASSIFICATION
• MORPHOLOGY
• PSEUDOPHYLLIDEAN CESTODES
• CYCLOPHYLLIDEAN CESTODES
• SUMMARY
• LABORATORY DIAGNOSIS
• KATO KATZ TECHNIQUE

3. • Cestodes are helminthic parasites,
multicellular, bilaterally symmetrical
having three germ layers.
• The helminth of medical importance are
divided into three main groups-
1. Cestode
2. Trematode
3. Nematode
Introduction

4. CESTODE TREMATODE NEMATODES
SHAPE Tape-like; segmented Leaf-like; unsegmented Elongated, cylindrical;
unsegmented
SEXES Not separate i.e.
Monoecious,
hermaphrodite
Not separate , except
schistomes which are
diecious
Separate- Diecious
“HEAD” END Suckers, often with
hooks
Suckers, no hooks. No suckers, no hooks
ALIMENTARY
CANAL
absent Present but incomplete;
no anus
Present and complete
BODY CAVITY absent absent present
Life cycle Requires two hosts
(except Hymenolepis
and
Diphyllobothrium)
Requires three hosts
(except Schistosoma)
Requires one host
(except fi larial worms
and
Dracunculus)
Differences between cestodes, trematodes and nematodes

5. • Long, segmented and tape-like, hence called
tapeworms.
• They are flattened dorsoventrally.
• Size vary from few millimeters to several meters.
• Adult worms are found in intestinal canal of man
and animal.
• Excretory and nervous systems are present. The
excretory canals are built up of flame cells
(terminal cells) and canal cells.
• There is no circulatory system and no body cavity.
• Reproductive system is highly developed and
complete in each segment.
General characteristic of cestode

6. Classification of Cestodes
• Systemic Classification
• Cestodes belong to -
Phylum—Platyhelminths
Class- Cestoidea
Subclass- Eucestoda

7. Classification Based on the habitat of the Cestodes
• Intestinal Cestodes (Adult Worm Residing in
Human Intestine)
Diphyllobothrium species
Taenia solium and Taenia saginata causing
intestinal taeniasis
Hymenolepis species
Dipylidium species.
• Somatic/Tissue Cestodes (Larvae in Human
Muscles/Organs)
Taenia solium causing cysticercosis
Taenia multiceps
Echinococcus species
Spirometra species

8. Morphology of Cestodes
• Morphological forms:
1. Adult worm
2. Egg
3. Larva
There are three regions in an adult worm-
I. Head (scolex),
II. Neck
III. Strobila (a body or trunk) consisting of series of segments
(proglottides).
• Head is provided with suckers(slit-like or cup-like) and sometimes with
hooks which serve as organs of attachment

9. Head (scolex)
T. saginata T. solium

10. Adult worm

11. • Reproductive system is highly developed
and complete in each segment.
• According to maturity of reproductive
organs-
three types of segments of the strobila can be
recognized from the front backwards:
1. Immature segments
2. Mature segments
3. Gravid segments or fertilized segments

12. EGGS
• Pseudophyllidean cestodes:
 Eggs are ovoid, operculated,
surrounded by a single layer
called as egg shell (or
capsule), inside which the
embryo is present containing
hooklets (three pairs).
 Membrane lining the embryo
is ciliated. The eggs when laid
first in the feces, are not
embryonated.
 Maturation takes place later in
water.
• Cyclophyllidean cestodes:
 Eggs are round to oval,
covered by two layers—
 An outer egg shell (or
capsule) filled with yolk
material (thin, so might be
lost) and
 An inner thick radially striated
embryophore surrounding
the embryo.
 Eggs are embryonated from
the beginning, contains six
hooklets.

13. LARVA
• Pseudophyllidean
cestodes:
• Larva is solid without any
sac.
– They are:
Coracidium: First stage
larva of Diphyllobothrium
Procercoid: Second stage
larva of Diphyllobothrium
Plerocercoid: Third stage
larva of Diphyllobothrium
• Cyclophyllidean
Cestodes:
– Larvae contain bladder
like sacs.
– Cysticercus: Larval stage
of Taenia
– Hydatid cyst: larval stage
of Echinococcus
– Cysticercoid: Larval
stage of Hymenolepis

14. PSEUDOPHYLLIDEAN CESTODE CYCLOPHYLLIDEAN CESTODE
Head Bears 2 longitudinal slit- like grooves-
called bothria
Bears 4 cup-like muscular suckers
(acetabula). In T. solium and H.
nana, scolex has a beak like apical
protrusion called as rostellum
Uterus No branching; the convoluted uterine
tube assume the form of a rosette.
Branching may or may not be
present.
Uterine pore Present Absent
Common genital
pore
Ventral in the midline. Lateral
Eggs Operculated; give rise to ciliated
larvae.
Non operculated; do not give rise to
ciliated larvae.
Larval form Solid Contains bladder like sac
Difference b/n a Pseudophyllidean Cestode and a
Cyclophyllidean Cestode

15. LIFE CYCLE
• Cestodes complete their life cycle in two hosts
(definitive host and intermediate host) except:
1. Hymenolepis- requires only one host—
man.
2. Diphyllobothrium requires three hosts
 one definitive host—man &
 two intermediate hosts–cyclops and fish.

16. Species Definitive host Intermediate host
D.latum Man, Dog, Cat Cyclops & Fish
T.saginata Man Cow
T.Solium Man Pig, Man
E. granulosus Dog, Wolf, Sheep, Cattle, Pig,
Man
H.nana Man, Rat Not required
D.caninum Dog, Cat Dog flea

17. Laboratory diagnosis
• Direct wet mount (saline and iodine mount)
 Drops of saline and Lugol’s iodine are placed on two corners of a
slide.
 A small amount of feces is mixed by a stick to form a uniform
smooth suspension.
 Cover slip is placed on the mount and examined under low
power objective (10X); followed by high power objective (40X).
 Some times proglottids of Taenia also found in stool
examination.
• For Cysticercosis
 Radiodiagnosis— CT scan and MRI
 Antibody detection in serum or CSF
• For Echinococcus granulosus
 Hydatid fluid microscopy- brood capsules and protoscolices
 Antibody detection – IHA, LAT
 Antigen detection- ELISA
 Imaging methods—X-ray, USG, CT scan, MRI
 Skin test (Casoni test)

18. Concentration Techniques
1. Sedimentation techniques:
– Eggs settle down at the bottom following
centrifugation-
Formalin-ether concentration technique
2. Floatation techniques:
– The eggs float at the surface due to specific gravity
gradient
Saturated salt (sodium chloride) solution technique
Zinc sulphate floatation concentration technique

19. Formol-ether sedimentation technique (schematic diagram)
zinc sulfate flotation concentration technique (schematic) diagram;

20. Kato katz technique
Used for counting of eggs in stool.
• Place a plastic template with hole of size 6mm on top of clean glass
slide.
• Place a small amount of the faecal sample on a newspaper and
press a piece of nylon screen on top.
• With a spatula, scrape the faecal material through the nylon screen
so that only the debris remains.
• Transfer a small amount of the sieved faecal material into the
hole of the template & carefully fill the hole
• Lift off the template, now slide contain sieved fecal sample
• Place one piece of the cellophane (which has been soaked
overnight in methylene blue glycerol solution) over the faecal
sample.

21. • Place a clean slide over the top and press it evenly
downwards to spread the faeces in a circle.
• Remove the slide by gently sliding it sideways to avoid
separating the cellophane strip.
• Place the slide with the cellophane upwards for 30–60
minutes
• Place the slide under a microscope and examine the
whole area for eggs of schistosomes & soil transmitted
helminthes.

24. HYDATID CYST
MicroscopyMacroscopic picture

25. Non bile stained egg of Hymenolepis nana in
• saline mount—three pairs of hooklets are seen clearly
• iodine mount— polar filaments are seen clearly

26. THANK
YOU