Unit 4 - Cestodes Flashcards
Acoelomates have:
NO body cavity
Describe the body shape of cestodes:
dorsoventrally flat chain of segments
Are cestodes monoecious or dioecious?
monoecious (hermaphroditic)
Where are the majority of cestode adults located?
SI
What life cycle stage of cestodes is typically not pathogenic?
adults
The body of the cestode is called a ______ and each of the segments are _________.
strobila; proglottids
Cestodes: direct or indirect life cycle?
indirect
How many intermediate hosts do “true” cestodes (Order Cyclophyllidea) have?
1
How many IH do “primitive” cestodes (Diphyllobothriidea) have?
2
What is the Cyclophyllidea scolex?
suckers +/- hooks
Diphyllobothriidea scolex?
Bothria (groove)
Genital pore location for Cyclophyllidea:
lateral
Diphyllobothriidea genital pore location:
medial (with the uterine pore)
How are Cyclophyllidea eggs shed?
in gravid proglottids; eggs without opercullum
How are Diphyllobothriidea eggs shed?
shed from pore in proglottids; eggs operculate
larval cestode in IH:
metacestode
Which stage of the cestode life cycle is more often associated with disease?
metacestodes
How many types of metacestodes do Cyclophyllideans have?
6 types (depends on species)
Metacestodes that develop into 1 adult in DH (only one worm is contracted):
- Cysticercus
- Strobilocercus
- Cysticercid
Metacestodes that develop into multiple adults in DH:
- Coenurus
- Unilocular hydatid cyst
- Alveolar (multiocular) hydatid
What are the two metacestode stages of Diphyllobothriideans? Which stage develops in 1st IH? 2nd IH?
Procercoid (1st IH), Plerocercoid (2nd IH)
Each plerocercoid develops into:
1 adult cestode
“bladder worm”
Cysticercus
Cysts in cysts; internal budding. Thick walled and slow growing:
Unilocular hydatid cyst (endogenous)
external budding:
alveolar (multiocular) hydatid (exogenous)
What are the two genera of importance from the Family Taeniidae?
Taenia, Echinococcus
What is the zoonotic potential of Taenia/Echinococcus?
humans may be DH or dead-end IH
DH and IH for Taenia, Echinococcus (Cyclophyllidea):
mammals (predator/prey)
DH for Taenia pisiformis:
canids
What is ingested by canids when dealing with Taenia pisiformis?
cysticercus
What is the IH for Taenia pisiformis?
rabbit
What is the DH for Taenia hydatigena?
canids
What is the IH for Taenia hydatigena?
ruminants, swine
Not as common as T. pisiformis in domestic dogs:
Taenia hydatigena
DH for Taenia taeniaeformis:
felids
IH for Taenia taeniaeformis:
rodents
larva ingested for DH infection with T. hydatigena:
cysticercus
What stage of T. taeniaeformis is ingested to cause infection in the DH?
strobilocercus
What is the general PPP for all Taenia spp.?
1.5 months
Pork tapeworm
Taenia solium