Cestodes, SECOND MBBS STUDENTS - UNDERGRADUATE STUDENTS - MEDICAL COLLEGE - POWERPOINT

1. CESTODES
Dr. R. Someshwaran, MD., Assistant professor,
Department of Microbiology, KFMS&R

2. Had lunch????
12/17/15 2MEU KFMS&R

3. Post-prandial somnolencia!!!
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4. OBJECTIVES
• At the end of this session you should be able:
To define the General characters,
Morphology, Disease caused, Laboratory
diagnosis and Treatment of Cestode
infections.
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5. HELMINTHOLOGY
• Helminths are multicellular, bilaterally animals
• Have 3 germ layers (triploblastic metazoa)
Helminths – 2 Phylum
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6. Cestodes Vs Trematodes Vs Nematodes
Differences between Cestodes, Trematodes & Nematodes
CESTODES TREMATODES NEMATODES
Shape Tape like
segmented
Leaf like
unsegmented
Elongated,
cylindrical,
unsegmented
Sexes Sexes not separate
Monoecious
Hermaphrodite
Sexes not separate
Monoecious except
Schistosoma
Sexes are separate
Diecious
Head end Suckers, often with
hooks
Suckers, no hooks No suckers, no
hooks, well
developed
Alimentary
canal
Absent Present,
incomplete, no
anus
Present, complete,
anus present
Body cavity Absent Absent Present
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7. General characters of cestodes
 Long, segmented and tape-like
 Tapeworms
 Flattened dorsoventrally
 Habitat: Adult worms in intestinal canal of
humans and animals
 Head is provided with suckers (Slit like or cup
like) and sometimes with hooks (attachment)
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8. General characters of cestodes
 Sexes are not separate (Hermaphrodite)
 Body cavity is absent
 Alimentary canal is entirely absent
 Excretory and nervous system are present
 Reproductive system – highly developed and
complete in all segment.
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9. General characters of cestodes
• 3 regions in an adult worm
1. Head (Scolex) 2. Neck
3. Strobila (body or trunk) containing series of
segments (Proglottids)
 Based of maturity of reproductive organ
1.Immature, 2. Mature, 3. Gravid
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10. General characters of cestodes
1.Immature:
Male and female organs not developed
2. Mature:
Male and female organs developed, male organs
appear first
3. Gravid:
Uteri filled with eggs (other organs atrophied or
disappeared)
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11. CESTODES
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12. ADULT WORM
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13. General characters of cestodes
Female reproductive system:
Ventral surface of each segment
- Ovary - single or paired
- Vagina - Seminal receptacle and seminal duct
-Uterus - Open in Pseudophyllidea,
Blind sac in cyclophyllidea
- Ootype - Vitelline glands - Mehlis glands
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14. General characters of cestodes
Male reproductive system:
Dorsal surface of each segment
-Testes ; Vas deferens / Cirrus sac
Pseudophyllidean cestodes: Egg is operculated
and has a single covering. Larval forms-
Procercoid and Plerocercoid
Cyclophyllidean cestodes: Not operculated and
has 2 coverings (Outer egg shell & Inner
embryophore). Larval forms becomes Bladder
worm12/17/15 14

15. TERMINOLOGIES USED
• Strobila – Body or Trunk; Scolex – Head
• Proglottid – Individual segment / complete
unit of tapeworm
• Rostellum – A beak like projection on head
• Oncosphere – A six hooked (Hexacanth
embryo) inside the egg
• Embryophore – Enveloping membrane
surrounding oncosphere
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16. TERMINOLOGIES USED
• Egg-shell: Outer membrane enclosing
oncosphere with embryophore
• Cysticercus: Resting stage of larva in
intermediate host – develops into ‘bladder
worm’
• Cysticercoid: A small bladder containing
invaginated head proximally and a solid
elongated portion
• Coenurus: Larval stage in form of Bladder
worm contain many invaginating scolices12/17/15 16

17. TERMINOLOGIES USED
• Hydatid cyst: Larval stage of Echinococcus
• Coracidium: A ciliated oncosphere of
Diphyllobothrium
• Procercoid: First larval stage of
Diphyllobothrium found in cyclops, contain
embryonal hooklets.
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18. Classification of Cestodes infecting man
• Pseudophyllidean cestodes:
Possessing false slit like grooves (bothria)
1.Adult worms in intestine:
i) Diphyllobothrium latum (Fish worm)
2. Larval stages (Plerocercoid) in man
i) Sparganum mansoni;
ii)Sparganum proliferum
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19. Classification of Cestodes infecting man
• Cyclophyllidean cestodes:
Possessing cup-like and round suckers
1.Adult worms in intestine:
i) Taenia solium (pork tapeworm)
ii)Taenia saginata (Beef tapeworm)
iii)Dipylidum caninum (Double-pored Dog
tapeworm)
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20. Classification of Cestodes infecting man
• Cyclophyllidean cestodes:
Possessing cup-like and round suckers
2. Larval stages in man2. Larval stages in man
i) Hydatid cyst of Echinococcus granulosus (Dog
tapeworm), Echinococcus multilocularis; ii)
Cysticercus cellulosae of Taenia solium
ii)Coenurus cerebralis of Multiceps multiceps,
Multiceps glomeratus, Multiceps serialis
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21. Pseudophyllidean Vs
Cyclophyllidean Cestodes
Differences between Pseudophyllidean Vs Cyclophyllidean Cestodes
Pseudophyllidean Cyclophyllidean
Head Bears 2 slit like grooves Bears 4 cup like suckers
Uterus No branching, rosette
shaped convoluted tubule
Branching may or may not
be present
Uterine pore Present Absent
Common genital
pore
Ventral, in the midline Lateral
Eggs Operculated giving rise to
ciliated larvae
Not operculated, do not
give rise to ciliated larvae
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22. General character of
Pseudophyllidean cestode
• Large worms containing a long chain of
segments
• Head has Bothria (2 slit like sucking grooves)
in place of suckers
• Vitelline glands scattered containing many
acini
• Genital pores on ventral surface but not
marginal
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23. General character of
Pseudophyllidean cestode
• Uterus opens to exterior through which eggs
comes out
• Eggs are operculated and can develop only in
water. Immature when oviposited.
Oncopshere gives rise to ciliated embryo
• Larval development precedes in intermediate
host. 1st
larval stage is called Procercoid and
second larval stage ‘Plerocercoid’
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24. Diphyllobothrium spp.,
• Diphyllobothrium latum
• Fish tapeworm
• Habitat: Small intestine (Ileum)
• Diphyllobothriasis
• Fish to Humans
• Eggs does not float in saturated salt solution
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25. Diphyllobothrium latum
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26. Diphyllobothrium spp.,
• Definitive host: Man, Dog, cat, Fox
• First intermediate host: Fresh water
crustacean, cyclops or a Diaptomus
• Second intermediate host: Fresh water fish,
pike, salmon, perch and etc.,
• First stage larva (Coracidium) into Second
stage larva called Procercoid larvae in
Cyclops
• Third stage larvaSparganum or Plerocercoid12/17/15 26

27. Diphyllobothrium latum
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28. Diphyllobothrium latum
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29. Diphyllobothrium latum
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30. Diphyllobothrium latum –
Bile stained eggs
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31. Size and segments number
• Taenia solium – 2-3 metres (<1000 Proglottids)
• Taenia saginata – 5-10 metres (1000-2000)
• Diphyllobothrium latum – 3-10 metres (3000-4000)
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32. General characters of
Cyclophyllidean cestodes
• Large or small worms containing chains of
segments
• Head is Quadrate in outline with four cup liked
round suckers at each of the four angles
• Apical rostellum in the center with hooklets
may be present
• Vitelline glands concentrated behind ovary
near the posterior margin of each segment
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33. General characters of
Cyclophyllidean cestodes
• Common genital pore is marginal (lateral side)
• No uterine opening for exit of eggs
• Eggs are not operculated and can develop
only in intermediate host
• Oncosphere is never a ciliated embryo
• Larval development proceeds only in one
intermediate host
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34. Taenia
• Taenia solium (Armed) or Pork tapeworm
• Taenia saginata (Unarmed) or Beef
tapeworm
• Habitat: Small intestine
• Infective forms:
• Taenia solium – Cysticercus cellulosae
• Causes Neurocysticercosis (Epilepsy)
• Taenia saginata – Cysticercus bovis
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35. Taenia spp., / Pork tapeworm
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36. Taenia Life cycle
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37. Taenia solium Life cycle
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38. Taenia saginata life cycle
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39. Taenia solium
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40. Taenia solium
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41. TAENIA
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42. TAENIA
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43. TAENIA
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44. Taenia solium & Taenia saginata egg
in stool Microscopy – Bile stained
• Eggs does not float in Saturated salt solution12/17/15 45

45. Egg of Taenia spp.,
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46. Taenia
To diagnose Neurocysticercosis:
Biopsy, X-ray, MRI, CT scan Brain –
calcifications
ELISA, Myelography (Spinal cysticerci)
You Cannot diferentiate between the
Eggs of Taenia solium and Taenia saginata!!!
1.Polymerased Chain Reaction (PCR)
2.Hooklets of Taenia saginata are Acid fast
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47. TREATMENT
• Praziquantel 5-10mg/kg single dose after
break fast
• Niclosamide 2 gm as a single dose
• Albendazole 400 mg BD
• Excision is best wherever possible.
• Note: Taenia saginata asiatica – Larger scolex.
Seen in Thailand, Taiwan, korea, Myanmar
and in Philippines
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48. ECHINOCOCCUS
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49. Echinococcus spp.,
• Echinococcus granulosus
• Dog tapeworm
• Echinococcosis
• Liver, lung, kidney
and brain of Humans
and cows
Habitat: Small intestine (Harbour only larval
form but not adult form)
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50. Echinococcus spp.,
• Definitive host: Dog, wolf, fox, jackal
• Intermediate host: Sheep, pig, cattle, goat and
man
• Larval form of e. granulosus causes Hydatid
disease
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51. Echinococcus granulosus
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52. Echinococcus granulosus
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53. Hydatid cyst
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54. Echinococcus spp.,
• Hydatid cyst
• 3 layers:
1.Pericyst or Adventitia ,
2.Outer Cuticular or External Laminated
membrane (Ectocyst) ,
3. Inner germinal layer (Endocyst)
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55. Hydatid cyst
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56. Hydatid fluid
• Clear, colorless (may be pale yellow)
• Low specific gravity (1.005-1.010)
• Slightly acidic, pH 6.7
• Contains sodium chloride, sodium sulphate,
sodium phosphate, sodium and calcium salts
of succinate
• Antigenic (immunological tests)
• Highly toxic – Anaphylaxis
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57. Hydatid sand
• Hydatid sand- settled granular deposit,
containd brood capsules, free scolices and
loose hooklets
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58. Hydatid cyst
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59. Diagnosis - Echinococcosis
• Casoni’s test: Immediate hypersensitivity test
• Blood examination: Eosinophilia
• Serology: CFT, Precipitin test, ELISA, IHAT, HA,
Flocculation tests, Latex tests, IFA, IEE
• Molecular methods: DNA probe, PCR
• Exploratory cyst puncture
• Radiological
• IV pyelogram (Renal hydatid cyst)
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60. Treatment - Echinococcosis
• Mebendazole
• Albendazole (400-800mg BD for 1-6 months)
• Prevention: By deworming of dogs, Personal
prophylaxis
• Note: Alveolar or Miltilocular hydatid cyst in
man is caused by echinococcus multilocularis
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61. HYMENOLEPIS NANA
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62. Hymenolepiasis spp.,
• Hymenolepis nana
• Hymenolepis diminuta
• Habitat: Small intestine
• Definitive host: Exception to general rule as
they do not multiply in the body of definitive
host
• Intermediate host: no intermediate host
required
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63. Hymenolepiasis nana
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64. Hymenolepiasis nana
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65. Hymenolepiasis nana
Diagnosis:
Stool microscopy: Non bile stained eggs
ELISA
Treatment:
Niclosamide 60-80mg/kg for 5-7 days
Praziquantel single dose 25mg/kg
Mebendazole sures 50% cases only
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66. Take home message & Summary
• Taenia solium – Pork tapeworm
• Taenia saginata – Beef tapeworm
• Diphyllobothrium latum – Fish tapeworm
• Hymenolepis nana – Dwarf tapeworm
• Hymenolepis diminuta – Rat tapeworm
• Echinococcus granulosus – Dog tapeworm
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67. Sleepers!!! Wake up!!!!
Class is over!!!
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68. THANK YOU
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