Cestodes

• What kingdom do cestodes belong to?

  Animalia
• What class do cestodes belong to?

  Platyhelminthes
• What subclass do cestodes belong to?

  Eucestoda
• What orders are included in cestodes?

  Pseudophyllidea and Cyclophyllidea
• Which specific cestode is mentioned in the study material?

  Diphyllobothrium latum
• What are the general characteristics of tapeworms?

  • Flat and ribbon-like
  • White and yellowish color
  • Segmented
  • Size variation from 3mm to 10mm
  • Generally require an intermediate host
  • Growth through addition of segments/proglottids
  • Monoecious and hermaphroditic
  • No gastrointestinal tract or circulatory system
  • Well-developed reproductive organs
  • Possess a nervous system
  • Have a tegument for nutrient exchange
• What is the shape of tapeworms?

  Flat and ribbon-like
• What colors are tapeworms typically?

  White and yellowish
• How do tapeworms grow?

  By the addition of segments called proglottids
• What is the size range of tapeworms?

  3mm to 10mm
• What does it mean that tapeworms are monoecious?

  They possess both male and female reproductive organs
• What is the function of the tegument in tapeworms?

  It serves as the outermost layer for entry and exit of nutrients
• What are the parts of the anterior portion of a tapeworm?

  • Scolex: has suckers and sometimes hooklets
  • Neck: region of growth and germination
  • Rostellum: fleshy extension of scolex, can be armed or unarmed
• What is the scolex of a tapeworm?

  The anterior portion that has suckers and sometimes hooklets
• What is the function of the neck in a tapeworm?

  It is the region of growth and location of the germination process
• How can the maturity of a proglottid be determined?

  By the distance of the segment to the neck; nearer is younger, farther is older
• What are the types of proglottids in tapeworms?

  • Immature: nearest to the neck
  • Mature: middle portion with reproductive structures
  • Gravid or Ripe: filled with eggs, undergo apolysis or anapolysis
• What is the term for a chain of proglottids?


  Strobilla
• What happens during apolysis in Cyclophyllidean cestodes?

  Separation of the gravid proglottid
• What is the difference between apolysis and anapolysis?

  Apolysis involves separation of the gravid proglottid, while anapolysis does not
• What is the treatment for cestodes?

  • Remove the scolex
  • Recovery of the scolex indicates success
  • Praziquantel (5 to 10 mg/kg)
• What are the differences between Pseudophyllidea and Cyclophyllidea cestodes?

  • Pseudophyllidea:
  • Head has bothria
  • No branching uterus
  • Uterine pore present
  • Cyclophyllidea:
  • Head has 4 cup-like suckers
  • Branching uterus may be present
  • Uterine pore absent
• What is the common genital pore location in Pseudophyllidea cestodes?

  Ventral in the midline
• What type of eggs do Pseudophyllidea produce?

  Operculated eggs
• What is the larval form of Pseudophyllidea cestodes?

  Solid
• What are the larval stages of Cyclophyllidea cestodes?

  1. Coracidium
  2. Procercoid
  3. Plerocercoid/Sparganum
  4. Cysticercus (Taenia)
  5. Cysticercoid (Hymenolepis)
  6. Hydatid (Echinococcus)
• What is the treatment for D. latum?

  Praziquantel
• What is the common associated disease with D. latum?

  Diphyllobothriasis
• What is the mode of infection for D. latum?

  Ingestion of undercooked/raw fish infected with plerocercoid
• What is the infective stage of D. latum?

  Plerocercoid larva
• What is the diagnostic stage of D. latum?

  Eggs and gravid proglottids
• Who are the definitive hosts of D. latum?

  Man and fish-eating mammals or birds
• What is the life cycle of D. latum?

  1. D. latum egg develops into coracidium
  2. Coracidium hatches and infects crustaceans
  3. Crustaceans are eaten by small freshwater fishes
  4. Plerocercoid larva develops in fish
  5. Humans ingest undercooked fish
  6. Adult tapeworm resides in the small intestine
• What are the clinical manifestations of Diphyllobothriasis?


  Digestive discomfort, fatigue, weight loss, and risk of Vitamin B12 deficiency
• What is the intermediate host for D. latum?

  1st - crustaceans, 2nd - small freshwater fishes
• What is the definitive host for Taenia saginata?

  Man
• What is the mode of infection for Taenia saginata?

  Eating uncooked beef containing cysticercus bovis
• What is the definitive host for Taenia solium?

  Man
• What is the mode of infection for Taenia solium?

  Eating undercooked pork containing cysticercus cellulosae
• What is the mode of infection for Cysticercosis/Neurocysticercosis?

  Eating fecal contaminated food with T. solium ova