Class Cestoda
Mar 31, 2015
Class Cestoda
General characters• All tape worms consist of long, multi-segmented
body.• Cuticle of the body is provided with pores
through which the worm takes its nutrients (no digestive system)
• They are hermaphroditic.• The adult worm is divided into 3 distinct parts:1. Head (scolex),2. neck 3. strobilla1. Head or scolex : usually provided with
muscular suckers and crown of hooks (rostellum) to attach to intestinal wall.
General characters cont.
2.Neck3. Strobilla: the long segmented body consists
of segments of three types (i) the immature segments: which follow the
neck region (ii) the mature segments: containing both sex
organs and are responsible for reproduction (iii) the gravid segments: filled with fertilized
eggs.• Eggs :contain hexacanth embryo• All worms have intermediate host except
Hymenolipis nana
Examples of class cestoda
1- Taenia sp:
Taenia saginata
Taenia solium
2- Hymenolepis sp:
Hymenolepis diminuta
3- Dipylidium caninum
4- Echinococcus granulosus
1.Taenia saginata
Taenia saginata mature segment: nearly square, bilobed ovary, scattered testis, uterus:median tube (4X)
Taenia saginata gravid segment longer than broad branched uterus filled with eggs (4X)
Egg of Taenia sp. circular,radiating double wall (H.P).
Taenia saginata cont.
• Location of adult: Small intestine of man
• Intermediate host : Cattle
• Infective stage : Cysticercus bovis
• Mode of transmission: Eating insufficiently cooked meat containing cysticercus bovis
• Diagnosis: Eggs & gravid segments in stool
• Disease: Taeniasis
2. Hymenolepis diminuta (rat tape worm)
Mature segments: broad than long characterized by 3 testis and one ovary in each segment (4X)
Gravid segments : broad than long, enlarged uterus containing eggs (4X)
2.Hymenolepis diminuta cont.
• 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
3. Dipylidium caninum (dog tape worm)
Mature segments: longer than broad,2 genital pores, testis and ovaries (4X)
Gravid segments: Longer than broad, wall deformed, enlarged uterus filled with eggs (4X)
Dipylidium caninum cont.
Egg packet
• 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
Dipylidium caninum cont.
4. Echinococcus granulosus
Adult worm:
scolex, immature, mature and gravid segments (4X)
Scolex from hydatid sand (H.P)
Echinococcus granulosus cont.
• 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: 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