Cestodes (tapeworms) Flashcards
- key characteristics - identify final and intermediate host - clinical relevance in each host - purpose of adults and larvae - Taenia solium - final and intermediate hosts - significance of the wrong life stage in the wrong host
1
Q
Cestodes (tapeworms)
A
- flat body without body cavity
- strobila (body) with head, neck and proglottids (segments)
- head: scolex with 4 suckers or bothria
- hermaphroditic (each proglottid)
- no alimentary canal
- indirect life cycle
- several types of larval stages
2
Q
cestode body
A
- flat; but with segments
3
Q
Cyclophyllidea
A
- 1 intermediate host
- organs of attachment associated with scolex and suckers
- egg contains and oncosphere
4
Q
Pseudophyllidea
A
- 2 intermediate hosts (1st a crustacean)
- organs of attachment associated with scolex and bothria
- egg contains an oncosphere with cilia for motility
5
Q
Mature segments
A
reproductive organs
6
Q
cyclophyllidea cestodes - life cycle
A
- Adult in final host
- segments (proglottids) in feces
- eggs released from proglottids
- eggs consumed by intermediate host
- larvae develop in intermediate host
- intermediate host consumed by final host
- adults rarely a problem unless heavy infection or young animals
- larval stages, especially in humans can cause damage
7
Q
segments release:
A
- oncosphere
- hexacanth embryo
8
Q
oncosphere/hexacanth
A
- embryo consumed by an intermediate host
- forms a larva/larvae
- purpose: to make a scolex
- several types of larvae, but only 1 type occurs for each tapeworm species
9
Q
Taenia solium
A
- flat; hermaphrodites
- final host: adult in intestine (clinical signs rare)
- proglottids in feces of final host
- oncosphere - hexacanth embryo
- intermediate host can have clinical signs
- final host eats the intermediate host
10
Q
final host: humans
A
- consume larva: eating uncooked pork
- adult T. sodium in small intestine
- not normally pathogenic
- Taeniasis: itchy rear end
- proglottids/oncosphere in feces
11
Q
intermediate host: pigs
A
- consumes hexacanth embryo in human feces
- forms a larva (cysticercus) in muscle/tongue
12
Q
What if person eats human feces?
A
- develops cysticercus
- can occur in brain: NCC neurocysticercosis
13
Q
human host
A
- aberrant and dead end host
- when human has larval stage
