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: Head (scolex), neck strobilla 1. Head or scolex : usually provided with muscular suckers and crown of hooks (rostellum) to attach to intestinal wall.

General characters cont. 2.Neck 3. 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

Dipylidium caninum cont. 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

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