Parasitology Lec- Cestodes

• Scolex/Head


  Anterior holdfast organs
• Rostellum


  • Consists of hooks (attachment of parasite to intestinal mucosa). Not all cestodes have hooks.
• Sucker


  • Aka acetabula, and capable of attachment
• Neck


  Budding zone or germinative zone
• Strobila


  The body of the cestodes
• Immature Strobila


  • Located near to neck
• Mature Strobila


  • Consists a well-developed reproductive organs
• Gravid Strobila


  • Consists of eggs, where the uterus is located
• Gravid Proglottid


  Individual segments of the body
• Apolytic


  • Detached but the ova are still inside
• Anapolytic


  • Eggs come out before detaching
• Phylum Platyhelminthes (Class Cestodes)

  • Pseudophyllidean
  • Cyclophyllidean
• Pseudophyllidean


  • Diphyllobothrium latum
• Referred to as "flatworms" or "tapeworms"
• Flat, segmented, ribbon-like bodies
• Hermaphroditic (complete reproductive system, testes for male, ovaries, and uterus for females)
• No circulatory system & no digestive system
• Bilateral symmetry
• Heteroxenous (they have two intermediate hosts or more)
• Ova


  Oval or Ellipsoidal, No hexacanth, Consists of a ciliated larval called coracidium
• Ova


  • Operculum- lid-structure at the anterior part
  • Terminal knob- aka abopercular knob
  • 2 sucking grooves - Midventral, Middorsal bothria
• Scolex


  • Spatulate, Almond-shaped
• Proglottids


  • Rosette-shaped uterus, Centrally located reproductive system
• Diphyllobothrium latum


  Fish broad tapeworm, Broad tapeworm, Russian Broad tapeworm
• Causative agent of Diphyllobothriasis, Fish tapeworm infection
• Size: 55-75 um long; 40-45 um wide
• Laboratory Diagnosis: Direct Fecal Examination
• Intermediate hosts


  • 1st IH – Copepod
  • 2nd IH – Fish
• Clinical symptoms


  • Digestive disorders
  • Weakness
  • Megaloblastic anemia with thrombocytopenia and leukopenia (Vitamin B12 deficiency) (Hypersegmentation of Neutrophils, 5 lobes instead of 2-3 lobes only)
• Treatment: PRAZIQUANTEL
• Note: Embryonation takes place in water
• Taenia spp.


  Pork Tapeworm, Beef Tapeworm
• Causative agent of Taeniasis, Pork tapeworm infection, Taeniasis, Beef tapeworm infection
• Laboratory diagnosis: DFS, India ink (Stain for Proglottids)
• Intermediate hosts


  • Pigs
  • Cows/Cattle
• Clinical symptoms


  • Digestive disorders and obstruction
  • Pruritis ani
  • Neurocysticercosis (T. solium- Humans, T. saginata- Cows) -Diagnosis: CAT Scan- Del Grutto's Classification
• Treatment: PRAZIQUANTEL, Surgical removal before anti-parasitic drug (for Cysticercosis, infection muscle of muscle called measly meat/ pork)
• Cysticercus


  Bladder worm
• IH: Goat, Sheep, Arthropds
• Taenia solium


  • Mature Segments: 100-200 follicular testes; 3 ovarian lobes (1 accessory)
  • Gravid Segments: Central trunk with 7-12 lateral uterine branches (dendritic/ finger-like) (thicker)