Helminths - Cestodes Flashcards
General characteristics of helminths:
Acoelomates - No body cavity. Flat, segmented chains. Monoecious - Both sexes in one segment. Each segment is reproductively independent. Adults usually in SI. Usually non-pathogenic.
Cestode segments are called:
Proglottids.
The anterior end of the cestode is called:
The scolex. This is the “holdfast organ”
Types: Acetabula (suckers) and Bothria (slit-like)
What type of life cycle do cestodes follow? DIrect or indirect?
Indirect!
What are the two important orders of cestodes?
Cyclophyllidea and Diphyllobothriidea
General characteristics of Cyclophyllidea:
“True” cestodes. Terrestrial. ONE IH, which could be many vertebrates. Acetabula scolex. Eggs in gravid proglottids.
General characteristics of Diphyllobothriidea:
“Primitive” cestodes. Aquatic. Require TWO IHs. 1st IH = copepod. 2nd IH is freshwater fish or vertebrates. Bothria scolex. Eggs are expelled from adults.
What is a metacestode?
Larval cestode in IH and more often associated with disease.
What is a procercoid?
Name for the Diphyllobothriidea in the first IH.
What is a plerocercoid?
Name of the Diphyllobothriidea in the 2nd IH.
Taenia pisiformis:
Most common cestode in dogs. Inverted scolex (inside worm). Proglottids are shed in feces. Larval type: cysticercus IH - rabbits, commonly in the liver. DH - dogs
Taenia hydatigena:
Proglottids shed in feces.
Larval type: cysticercus
IH - ruminants/swine, commonly in peritoneum.
DH - dogs.
Taenia taeniaeformis:
The only one in the cat!
Larval type: strobilocercus
IH - usually rodents.
DH - cat
T. multiceps and T. serialis:
Enter sheep brains and cat brains respectively.
T. solium and T. saginata:
Pork tapeworm and Beef tapeworm respectively.
Humans may become accidental IH of solium, but not saginata. Humans can self-infect!
