3- Blood Fluke Schistosoma sp. Schistosoma mansoni male Schistosoma mansoni female Schistosoma mansoni male & female Schistosoma haematobium male Schistosoma haematobium female Eggs of Schistosoma mansoni Eggs of Schistosoma haematobium Snail of Schistosoma mansoni Snail of Schistosoma haematobium S. mansoni cercaria

S. mansoni (male & female) Schistosoma mansoni S. mansoni (male) 8-10 mm long has gynaecophoric canal dorsal surface covered with tubercle S. mansoni (female) 14 mm long taller and thinner vitelline glands occupy 2/3 of the body S. mansoni (male & female)

S. mansoni (snail) Biomphalaria alexandrina S. mansoni (egg) oval with lateral spine Cercaria of S. mansoni elongated head biforked tail

Schistosoma haematobium Egg oval with terminal spine Snail Bulinus truncatus

veins of urinary bladder (venous plexus of urinary bladder) S. haematobium S. mansoni veins of urinary bladder (venous plexus of urinary bladder) veins of large intestine, colon (lower mesentric vein) Location Bulinus truncatus Biomphalaria alexandrina Intermediate host Eggs in urine Eggs in stool Diagnosis Cercariae Infective stage Direct skin penetration of cercariae during swimming Mode of transmission Urinary Bilharziasis Intestinal Bilharziasis Disease

Class Cestoda

General Characters Tape Worms 1- All worms have long flat (no body cavity), multi-segmented body. 2- The body is covered with 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).

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

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

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

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).

Taenia saginata (Beef Tape Worm) Length: up to 10 m Taenia saginata mature segment: nearly square, bilobed ovary, scattered testis, uterus: median tube (magnifier) Taenia saginata gravid segment longer than broad branched uterus filled with eggs (magnifier)

Taenia sp. Egg circular, radiating (striated) double wall (H.P)

Taenia saginata 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

Hymenolepis diminuta (Rat Tape Worm) Length: 20-60 cm Mature segments: Broader than long characterized by 3 testis and one ovary in each segment (magnifier) Gravid segments: Broader than long, enlarged uterus containing eggs (magnifier)

Hymenolepis diminuta 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

Hymenolepis nana (Dwarf Tape Worm) Length: Very small 15-40 mm Mature segments: broader than long, characterized by 3 testis and one ovary in each segment (L.P)

Hymenolepis nana 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 in stool Disease: Hymenolepiasis

Dipylidium caninum (Dog Tape Worm) Length: 10-50 cm Cucumber seed-like or barrel shape Mature segment: Longer than broad, 2 genital pores, testis and ovaries (magnifier) Gravid segment: Longer than broad, deformed wall, enlarged uterus filled with eggs (magnifier)

Dipylidium caninum Egg Packet: round to oval and containing 5-15 eggs (H.P) Scolex: showing 4 suckers and extended rostellum with four rows of hooks (L.P)

Dipylidium caninum 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

Echinococcus granulosus (Hydatid Tape Worm) Length: 3-9 mm Adult worm: scolex, immature, mature and gravid segments (4X)

Echinococcus granulosus Protoscolex from hydatid cyst (H.P)

Echinococcus granulosus 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