Cestodes Flashcards
What type of worm are platyhelminthes?
Flatworms
What is a more common name for Class Trematoda?
Flukes
What is a more common name for Class Cestoda?
Tapeworms
What type of life cycle do all tapeworms have?
Indirect
What is the scolex of a tapeworm? Where is it located?
It’s the hold fast organ that allows nutrients to be absorbed across the tegument
It’s located on the anterior end
What is the strobila of a tapeworm?
It is all of the body segments put together
What are the individual body segments of a tapeworm called?
Proglottids
Describe the growth of a tapeworm.
TWs grow longitudinally. There are germinal cells in the neck that will continue adding proglottids.
As the proglottid moves away from the scolex, it starts to mature
What does the term “gravid” mean in terms of tapeworms?
Just means that the proglottid contains eggs
These are the proglottids that will break off from the worm and pass in the feces
What two features of a tapeworm anchor the worm to the SI?
The scolex (using suckers) and the rotellum (tip of the scolex that has hooks)
Do tapeworms have a digestive tract?
No, all of their nutrients come from the environment and are just absorbed across the integument
Where do most adult tapeworms reside and cause infection in their host?
The small intestine
What genus and species is the exception and does not reside in the small intestine as an adult? Where does it reside?
Anoplocephala perfoliata
It infects the cecum around the ileocecal junction
What are the two classes of cestodes (tapeworms) that are of importance to us?
Cyclophyllidea and Pseudophyllidea
What are genital pores used for?
They use the pores to fertilize themselves (they’re hermaphroditic) or other worms
Generally, if there’s more than 1 worm, there’s sexual reproduction
Do eggs come out of genital pores in tapeworms?
No, the eggs are contained in the proglottid and only come out if it ruptures
What stage of a tapeworm’s lifecycle is clinically relevant to us?
Larve
What is a metacestode?
Baby tapeworm
What are bothria?
The order pseudophyllidea have bothria on their scolex. Instead of round suckers they have bothria which are slit-like grooves
Which order do most tapeworms of birds and mammals belong to?
Cyclophyllidea
Cyclophyllidean TW eggs contain what?
A hexacanth embryo (AKA oncosphere)
What is a hexacanth embryo?
An embryo with 6 hooks
What will a hexacanth embryo differentiate into?
A metacestode (some called bladderworms, because they look like tiny bladders)
What is the infective stage to the DH when it comes to cyclophyllidean TWs?
Metacestode
What stage of a cyclophyllidean TW is ingested by the IH?
The hexacanth embryo. It develops into a metacestode in the IH.
What are the TWs of small animals with vertebrate prey-species as the IH?
Taenia spp. and Echinococcus spp.
What are the TWs of large animals with arthropod IHs?
Anoplocephala spp.
Paranoplocephala
Moniezia spp.
What are the TWs of small animals with arthropod IHs?
Dipylidium caninum
What are the two TWs we will talk about in order Pseudophyllidea?
Dibothriocephalus latum
Spirometra mansonoides
What is the common name for Taenia spp.? What genus and species is an exception?
Armed Tapeworm (hooks on the rostellum) T. saginata does not have hooks
What is the DH and IH of Taenia spp.?
DH - Carnivores (cats and dogs)
IH - vertebrate prey species
Where is the site of infection for adult Taenia and Taenia metacestodes?
Adults - small intestine
Metacestodes - in a variety of organs and tissues in the IH
What is the DH and IH of Taenia pisiformis?
DH - canines
IH - rabbits and hares
