L4: Cestodes

• Cestodes - commonly known as flat worms
• Cestodes general characteristics :

  • flat, segmented, ribbon-like bodies
  • Hermaphroditic - have a reproductive system (male: testis ; female: ovary and uterus)
  • No circulatory system and no digestive system
  • bilateral symmetry
  • heteroxenous - have 2 intermediate hosts or more
• parts of the cestodes :

  1. scolex - the whole cast organ in the cestode (capable of attachment)

  → rostellum - consists of hooks. this is used for the attachment of the parasite.

  → suckers (acetabula) - also used for attachment

  2. Neck - budding zine (germinative zone) - this is where the body comes from

  3. strobila - the body of cestode, consisting of a single and individual segment called proglottids
• 3 parts of strobila :

  1. immature proglottid
  2. mature proglottis
  3. gravid proglottid
• not all cestodes have hooks
• when identifying the morphology, it is important to know the scolex, immature, mature, and gravid proglottids

  
• the darky stained in the mature proglottids are the ovary and reproductive system
• ovaries can be seen more in the mature proglottid
• 2 kindsnof gravid proglottids :

  1. Apolytic
  2. Anapolytic
• Apolytic - it will be detached but the egg remains inside
• Anapolytic - before it detached in the segment of the body, the egg will go outside first

  
• Apolytic - kind of gravid proglottids

  
• General life cycle : Pseudophyllidean

  
• General life cycle : Pseudophyllidean

  • starts with the fertilized egg embryonating in the water. Pseudophyllidean only embryonate in water.
  • once they got embryonated, larvae formation occurs.

  L1 - Coracidium, L2 - Procercoid, L3 - Plerocercoid (The infective stage)

  • This larvae stages are ingested by intermediate host
• Pseudophyllidean intermediate hosts - has two intermediate host

  1st - L1 (Coracidium) L2 (Procercoid)

  2nd - L3 (Plerocercoid)
• Diphyllobothrium latum common name - fish broad tapeworm, broad tapeworm, russian broad tapeworm
• Diphyllobothrium latum causative agent of Diphyllobothriasis - fish tapeworm infection
• Diphyllobothrium latum size - 55 to 75 um long, 40 to 45 um wide
• Diphyllobothrium latum laboratory diagnosis - direct fecal examination
• Diphyllobothrium latum morphological characteristics : Egg / ova

  
• Diphyllobothrium latum morphological characteristics : Egg / ova

  Appearance :

  • oval or ellipsoidal
  • no hexacanth
  • consists of ciliated larval stage called coracidium

  Features :

  • Operculum : lid-structure at the anterior part
  • terminal knob : aka abopercular knob
• Diphyllobothrium latum larval stage : coracidium

  
• Diphyllobothrium latum larval stage : Procercoid

  
• Diphyllobothrium latum larval stage : Plerocercoid

  
• Coracidium is not usually seen inside since the visual cannot be seen. However, this is the only ciliated larval stage in Pseudophyllidean.
• Coracidium - located inside a shell of a Diphyllobothrium latum
• Plerocercoid - it will further elongate until it will have mature segments. once it becomes adult, the head (scolex), there is a distinct features.
• Diphyllobothrium latum : scolex

  
• Diphyllobothrium latum : scolex

  • Appearance - spatulate almond-shaped
  • Distinguishing features - 2 sucking grooved (midventral and middorsal bothria)
• Diphyllobothrium latum : proglottids

  
• Diphyllobothrium latum : proglottids

  • Appearance - rosette-shaped uterus
  • Distinguishing features - centrally located reproductive system
• Diphyllobothrium latum : Adult

  
• Diphyllobothrium latum : adult form

  • the body is BROAD that is why they called it “broad tapeworm”
• Diphyllobothrium latum clinical symptoms

  1. digestive disorder
  2. weakness
  3. megaloblastic anemia with thrombocytopenia and leukopenia (vb12 deficiency)
• when you have vitamin b12 deficiency, the feature in laboratory test is thrombocytopenia (low platelets) and leukopenia (low wbc)
• Diphyllobothrium latum blood cells feature :

  Hyper segmentation : it happens in the neutrophils. the one that hyper segment is the nucleus.
• Diphyllobothrium latum : blood cells feature

  • normal nucleus in neutrophil : 2 to 3 nucleus (lobes) only
  • If you have megaloblastic anemia : 5 nucleus (lobes) in the neutrophil
• Diphyllobothrium latum treatment - praziquantel
• Cyclophyllidean - comes from the embryonated egg in its host
• Cyclophyllidean host - domestic animals such as pigs and cows (goats, sheep, and other arthropod) from the soil, it will be eaten by the animals