1. Class Cestoda Pathology and Parasitology Course Code: 401
Parasitology-lab #3
Class Cestoda
Department of Microbiology & Immunology
Faculty of Pharmacy
Cairo University

2. General Characters Tapeworms
1- All worms have long flat (no body cavity), multi-segmented body.
2- The body is covered with a cuticle that is provided with pores through which the worm uptakes its nutrients (no digestive system).
3- All are hermaphrodites (each segment contains both male and female sexual organs).

3. 4- The adult worm is divided into 3 distinct parts:
a- Head or Scolex: usually with 4
muscular suckers and a crown
of hooks (rostellum) to attach to the
intestinal wall.
b- Neck Region: serves as a
generative organ
c- Strobilla: three types of segments
(Proglottids).
i. Immature: following the neck region
ii. Mature: containing both sex organs
and responsible for reproduction
iii. Gravid: filled with fertilized eggs

4. 5- Eggs: contain hexacanth
embryo (oncosphere).
6- All cestodes have an intermediate host except Hymenolepis nana(may have or maynot) .

5. Examples of Class Cestoda
1- Taenia sp.
Taenia saginata
Taenia solium
2- Hymenolepis sp.
Hymenolepis diminuta
Hymenolepis nana
3- Dipylidium caninum
4- Echinococcus granulosus

6. General life cycle of Cestodes
1. The adult worm matures in human intestine (final host).
2. Eggs shed in feces are released into environment.
3. Eggs are eaten by grazing animals (intermediate host).
4. Larval forms encyst in animals’ tissue.
Humans ingest encysted larvae in meat of infected animal (except in case of Echinococcus granulosus).

7. Taenia saginata (Beef Tapeworm) Length: up to 10 m
Location of adult: small intestine of man
Intermediate host : cattle (beef)
Infective stage : Cysticercus bovis
Mode of transmission: eating insufficiently cooked meat containing Cysticercus bovis
Diagnosis: eggs & gravid segments in stool
Disease: Taeniasis
Taenia saginata mature segment: nearly square, bilobed ovary, scattered testis, uterus: median tube
(magnifier)

8. Taenia saginata (Beef Tapeworm) Length: up to 10 m
Location of adult: small intestine of man
Intermediate host : cattle (beef)
Infective stage : Cysticercus bovis
Mode of transmission: eating insufficiently cooked meat containing Cysticercus bovis
Diagnosis: eggs & gravid segments in stool
Disease: Taeniasis

9. Taenia saginata (Beef Tapeworm) Length: up to 10 m
Location of adult: small intestine of man
Intermediate host : cattle (beef)
Infective stage : Cysticercus bovis
Mode of transmission: eating insufficiently cooked meat containing Cysticercus bovis
Diagnosis: eggs & gravid segments in stool
Disease: Taeniasis
Taenia saginata gravid segment longer than broad branched uterus filled with eggs
(magnifier)

10. Taenia saginata (Beef Tapeworm) Length: up to 10 m
Location of adult: small intestine of man
Intermediate host : cattle (beef)
Infective stage : Cysticercus bovis
Mode of transmission: eating insufficiently cooked meat containing Cysticercus bovis
Diagnosis: eggs & gravid segments in stool
Disease: Taeniasis
Circular with radiating (striated) double wall
(H.P)

11. Hymenolepis diminuta (Rat Tapeworm) Length: 20-60 cm
Location of adult: small intestine of rat occasionally man
Intermediate host: rat flea
Infective stage: cysticercoid
Mode of transmission: ingestion of rat flea containing cysticercoid
Diagnosis: eggs and gravid segments in stool
Disease: hymenolepiasis
Mature segments: Broader than long characterized by 3 testis and one ovary in each segment (magnifier)

12. Hymenolepis diminuta (Rat Tapeworm) Length: 20-60 cm
Location of adult: small intestine of rat occasionally man
Intermediate host: rat flea
Infective stage: cysticercoid
Mode of transmission: ingestion of rat flea containing cysticercoid
Diagnosis: eggs and gravid segments in stool
Disease: hymenolepiasis

13. Hymenolepis diminuta (Rat Tapeworm) Length: 20-60 cm
Location of adult: small intestine of rat occasionally man
Intermediate host: rat flea
Infective stage: cysticercoid
Mode of transmission: ingestion of rat flea containing cysticercoid
Diagnosis: eggs and gravid segments in stool
Disease: hymenolepiasis
Gravid segments: Broader than long, enlarged uterus containing eggs (magnifier)

14. Hymenolepis nana (Dwarf Tapeworm)
Length: Very small mm

15. Hymenolepis nana (Dwarf Tapeworm)
So there are 2 different routes in this life cycle:
1-without intermediate host
2-with flea as intermediate host

16. Hymenolepis nana (Dwarf Tapeworm) Length: Very small 15-40 mm
Location of adult: small intestine of man
Intermediate host: none
Infective stage: eggs
Mode of transmission: eating food contaminated with eggs or autoinfection
Diagnosis: eggs and gravid segment in stool
Disease: Hymenolepiasis
Mature segments: broader than long, characterized by 3 testis and one ovary in each segment (L.P)

17. Hymenolepis nana (Dwarf Tapeworm) Length: Very small 15-40 mm
Location of adult: small intestine of man and rodents
Intermediate host: flea
Infective stage: cysticercoid
Mode of transmission: ingestion of cysticercoid –containing flea
Diagnosis: eggs and gravid sement in stool
Disease: Hymenolepiasis
Mature segments: broader than long, characterized by 3 testis and one ovary in each segment (L.P)

18. Dipylidium caninum (Dog Tapeworm) Length: 10-50 cm
Cucumber seed-like or barrel shape
Location of adult: small intestine of dogs, occasionally man
Intermediate host: dog flea
Infective stage: cysticercoid
Mode of transmission: ingestion of dog flea containing cysticercoid
Diagnosis: egg packet in stool
Disease: Dipylidium caninum infection
Mature segment: Longer than broad, 2 genital pores, testis and ovaries
(magnifier)

19. Dipylidium caninum (Dog Tapeworm)
Scolex: showing 4 suckers and extended rostellum with four rows of hooks (L.P)
Gravid segment: Longer than broad, deformed wall, enlarged uterus filled with eggs
(magnifier)

20. Dipylidium caninum (Dog Tapeworm) Length: 10-50 cm
Location of adult: small intestine of dogs, occasionally man
Intermediate host: dog flea
Infective stage: cysticercoid
Mode of transmission: ingestion of dog flea containing cysticercoid
Diagnosis: egg packet in stool
Disease: Dipylidium caninum infection

21. Dipylidium caninum (Dog Tapeworm) Length: 10-50 cm
Location of adult: small intestine of dogs, occasionally man
Intermediate host: dog flea
Infective stage: cysticercoid
Mode of transmission: ingestion of dog flea containing cysticercoid
Diagnosis: egg packet in stool
Disease: Dipylidium caninum infection
Egg Packet: round to oval and containing 5-15 eggs
(H.P)

22. Echinococcus granulosus (Hydatid Tapeworm) Length: 3-9 mm
Infective Stage
Final Host
Intermediate Host
Man (End Stage intermediate Host)
Diagnostic Stage

23. Echinococcus granulosus (Hydatid Tapeworm) Length: 3-9 mm
Location of adult: small intestine of dogs
Location of hydatid cyst : liver, lung, CNS and bone in man, cattle and sheep
Intermediate host: cattle, sheep (man is an end stage intermediate host)
Infective stage (for human): eggs in feces
Mode of transmission: man is infected by ingestion of eggs in dog feces
Diagnosis: identification of hydatid cyst by X-ray
Disease: hydatid disease
Adult worm: scolex, immature, mature and gravid segments
(4X)

24. Echinococcus granulosus (Hydatid Tapeworm) Length: 3-9 mm
Location of adult: small intestine of dogs
Location of hydatid cyst : liver, lung, CNS and bone in man, cattle and sheep
Intermediate host: cattle, sheep (man is an end stage intermediate host)
Infective stage (for human): eggs in feces
Mode of transmission: man is infected by ingestion of eggs in dog feces
Diagnosis: identification of hydatid cyst by X-ray
Disease: hydatid disease
Protoscolex from hydatid cyst
(H.P)

25. Echinococcus granulosus (Hydatid Tapeworm) Length: 3-9 mm
Location of adult: small intestine of dogs
Location of hydatid cyst : liver, lung, CNS and bone in man, cattle and sheep
Intermediate host: cattle, sheep (man is an end stage intermediate host)
Infective stage (for human): eggs in feces
Mode of transmission: man is infected by ingestion of eggs in dog feces
Diagnosis: identification of hydatid cyst by X-ray
Disease: hydatid disease
An adult worm resides in the small intestine of a definitive host. Afterwards, gravid proglottids release eggs that are passed in the feces of the definitive host. The egg is then ingested by an intermediate host. The egg then hatches in the small intestine of the intermediate host and releases an oncosphere that penetrates the intestinal wall and moves through the circulatory system into different organs, in particular the liver and lungs. Once it has invaded these organs, the oncosphere develops into a cyst. The cyst then slowly enlarges, creating protoscolices and daughter cysts within the cyst. The definitive host then becomes infected after ingesting the cyst-containing organs of the infected intermediate host. After ingestion, the protoscolices attach to the intestine. They then develop into adult worms and the cycle starts all over again.

26. Echinococcus granulosus (Hydatid Tapeworm) Length: 3-9 mm
Location of adult: small intestine of dogs
Location of hydatid cyst : liver, lung, CNS and bone in man, cattle and sheep
Intermediate host: cattle, sheep (man is an end stage intermediate host)
Infective stage (for human): eggs in feces
Mode of transmission: man is infected by ingestion of eggs in dog feces
Diagnosis: identification of hydatid cyst by X-ray
Disease: hydatid disease
Echinococcus granulosus hydatid cyst