Cestodes I and II Flashcards
What are the characteristics of class Cestoda?
Acoelomates
Dorsoventrally flat chain of segments
Monoecious
Where are adult cestodes usually found?
DH small intestine (there are some exceptions)
Are adult cestodes usually pathogenic?
No
What are cestode segments?
Proglottids
What is the cestode body?
Strobila
What is the anterior end of the cestode?
Scolex
Describe the scolex
Holdfast organ
May have specialized attachment organs (acetabula/suckers, bothria, bothridia)
What type of life cycle do cestodes use?
Indirect
Is the DH of cestodes a predator or prey?
Predator
Is the IH of cestodes a predator or prey?
Prey
What is the general indirect life cycle of cestodes?
Proglottids with eggs in feces Eggs in environment ingested IH with metacestode (larval stage) in tissues IH ingested DH with cestode in SI
What are the 2 important cestode orders?
Cyclophyllidea
Diphyllobothriidea
What are the cestodes that fall under Cyclophyllidea?
Taenia spp Echinococcus spp Diplyidium caninum Moniezia sp Anoplocephala spp Paranoplocephala mamillana Thysanosoma sp Mesocestoides corti
What are the cestodes that fall under Diphyllobothriidea?
Sprimetra spp
Diphyllobothrium latum
What order are the true cestodes?
Cyclophyllidea
What order are the primitive cestodes?
Diphyllobothriidea
Describe true cestodes
Terrestrial life cycle
Cestode larvae require 1 IH, which are various vertebrates and invertebrates
Describe primitive cestodes
Aquatic life cycle
Cestode larvae require 2 IHs, the first is a copepod and the second is a fish or non-fish vertebrate
Describe the scolex of Cyclophyllidea
Suckers +/- hooks
Describe the eggs of Cyclophyllidea
Shed in gravid proglottids; eggs without operculum
What is the genital pore location in Cyclophyllidea?
Lateral
How many IH(s) are there for Cyclophyllidea?
1
Describe the larval stage of Cyclophyllidea
6 types
Describe the scolex of Diphyllobothriidea
Bothria (grooves)
Describe the eggs of Diphyllobothriidea
Shed from pore in proglottids; eggs operculate
What is the genital pore location in Diphyllobothriidea?
Medial (with uterine pore)
How many IH(s) are there for Diphyllobothriidea?
2
Describe the larval stage of Diphyllobothriidea
2 stages
What is a larval cestode in IH?
Metacestode
Which are more often associated with disease, metacestodes or adult cestodes?
Metacestodes
What do the 6 types of Cyclophyllidean larval stages depend on?
Species
Describe the 6 types of Cyclophyllidean larval stages
Metacestodes that develop into 1 adult in DH:
Cysticercus
Strobliocercus
Cysticercoid
Metacestodes that develop into multiple adults in DH:
Coenurus
Uniocular hydatid cyst
Alveolar (multiocular) hydatid
What are the 2 stages for Diphyllobothriideans?
Procercoid develops in 1st IH
Plerocercoid develops in 2nd IH
—-Each plerocercoid develops into 1 adult cestode
Describe cysticercus
“bladderworm”
Small, fluid-filled; scolex inside
e.g. taenia pisiforms
Develops into 1 adult
Describe strobilocercus
Fluid-filled bladder, but scolex everted
Taenia taeniaformis
Develops into 1 adult
Describe cysticercoid
Solid (vs bladder); scolex inside
Cestodes with arthropod IH
Dipylidium caninum, Anoplocephalids
Develops into 1 adult
Describe coenurus
Multiple larvae attached in cyst
Taenia multiceps
Develops into multiple adults
Describe uniocular hydatid cyst
Cysts in cysts; internal budding
Thick-walled; slow growing
Echinococcous granulosis
Develops into multiple adults
Describe alveolar (multiocualr) hydatid
External budding
Thin-walled; invasive; faster growht
Echinococcous multilocularis
Develops into multiple adults
What budding does unilocular hydatid cyst have?
Endogenous budding (slow growing; thick-walled)
What budding does mutliocular have?
Exogenous budding (fast growing; thin-walled)
What are the 2 genera of importance in the Cyclophyllidea family Taeniidae?
Taenia
Echinoccocus
What are the DH and IH of Taeniidae?
Mammals
Is the family Taeniidae zoonotic?
Yes, humans may be DH or dead-end IH
What is used to treat cestodes?
Praziquantel
Epsiprantel
Fenbendazole
NOT avermectins/milbemycins
What is the DH of Taenia pisiformis?
Canids
What is the IH of Taenia pisiformis?
Rabbit
What is the life cycle of Taenia pisiformis?
Cysticercus is digested by DH –> scolex embeds in SI mucose –> develops in adult
Proglottids shed in feces
Egg ingested by IH, hatches –> hexacanth embryo migrates to organ –> develops into cysticercus
What is the DH of Taenia hydatigena?
Canids
What is the IH of Taenia hydatigena?
Ruminants, swine