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33 - -Blood FlukeBlood 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
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
Cercaria of S. mansoni
• elongated head
• biforked tail
S. mansoni (egg)
• oval with lateral spine
Schistosoma haematobium
Egg• oval with terminal spine
Snail
Bulinus truncatus
S. mansoniS. haematobium
Locationveins of large intestine, colon (lower mesentric vein)
veins of urinary bladder (venous plexus of urinary bladder)
Intermediate host
Biomphalaria alexandrinaBulinus truncatus
DiagnosisEggs in stoolEggs in urine
Infective stage
Cercariae
Mode of transmission
Direct skin penetration of cercariae during swimming
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 crownof hooks (rostellum) to attach to theintestinal 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 organsand 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 Cestoda1- Taenia sp. Taenia saginata Taenia solium
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.5. Humans ingest encysted larvae in meat of infected animal