Trematodes & Acanthocephelans Flashcards
- Definitions - parasites of veterinary importance - modes of infection - life cycles - intermediate hosts - paratenic (transport) hosts - dead-end hosts - parasite fitness - sites of infection - parasite/host balance and the environment - potential benefits of having parasites
1
Q
Helminths
A
- parasitic worms
- large, multicellular
- vermiform “Worm-like” in form
- Phylum Platyhelminthes (flatworms)
- Class Trematoda (flukes: endoparasites)
- Phylum Acanthocephala (thorny-headed worms)
2
Q
vermiform
A
“worm-like”
3
Q
Class Trematoda
A
- flukes
- endoparasites
4
Q
Phylum Platyhelminthes
A
flatworms
5
Q
Phylum Acanthocephala
A
thorny-headed worms
6
Q
Trematodes
A
- digeneans or digenean flukes
7
Q
Digenea
A
- subclass of trematodes
- parasitic flatworms (flukes)
- 2 suckers (ventral and oral)
- common in digestive tract
8
Q
Aspidogastrea
A
- subclass of trematodes
- parasites of freshwater and marine mollusks and vertebrates
9
Q
Fasciola hepatica
A
- common liver fluke or sheep liver fluke
- parasitic trematode
- infects livers of various mammals including humans
10
Q
trematodes (flukes)
A
- torso-ventrally flattened (leaf-like)
- oral and ventral suckers for attachment and feeding
- hermaphorditic
- can cross-reproduce
- heavy large eggs -> sedimentation
- operculated eggs
- no anus; waste material egested through mouth or via specialized cells (flame cells)
11
Q
trematodes (flukes): Simple life cycle
A
- final host: adult
- environment: egg -> miracidium
- intermediate host: rediae - cercaria
- environment: metacercaria
- final host: immature adult to adult
- final host consumes metacercaria in the environment
12
Q
miracidium
A
- penetrates into snail (intermediate host)
13
Q
cercaria
A
- free-swimming: encysts as a metacercaria in the environment or in the 2nd intermediate host
14
Q
trematodes (fluke) - complex life cycle
A
- adult: final and definitive host
- egg: environment - miracidium
- rediae: intermediate host (snail)
- cercaria: into environment again
- metacercaria: 2nd intermediate host, primary host or environment
- young adult to adult: final and definitive host
- final host consumes metacercaria in the 2nd intermediate host or primary host or in the environment
