Ch. 10,13,15 Flashcards
Define degeneracy.
loss of original information
Define metabolic dependency.
loss of metabolic capabilities
________ parasitism may have ‘devolved’ by free-living, facultatively developing, arrested larvae becoming associated with animals, ultimately becoming parasites.
Trematode
Define displacement.
no longer in original place and host association
What is the life cycle of the black spot parasite?
1) Adult develops in the bird definitive host
2) Egg passes from kingfisher + hatches in water –> matures into miracidium
3) Miracidium penetrates snail
4) Sporocyst larval stage in snail
5) Sporocyst larval stage in snail develops into cercaria and emerges from snail
6) Cercaria penetrates fish + develops into metacercaria
About how long is the trematode fluke cycle?
21 days
What fluke life stages are found in snails?
Miracidium, Mother Sporocyst, Daughter Sporocyst, Cercaria
What fluke life stages are found in fish?
Metacercaria
what fluke life stages are found in the Kingfisher?
Adult Fluke
What are the 4 major human organs in which trematode endoparasites can be found?
1) small intestine
2) liver
3) lungs
4) blood vessels
What endoparasites are found in the small intestine?
1) Echinostoma spp.
2) Fasciolopsis buski
What endoparasites are found in the liver?
1) Fasciola hepatica
2) Clonorchis & Opisthorchis spp.
What endoparasites are found in the lungs?
Paragonimus spp.
What endoparasites are found in the blood vessels?
Schistosoma spp.
What is the reservoir host of trematodes?
bull looking animal
what is the definitive host of trematodes (where sexual reproduction occurs)?
vertebrates (specifically humans)
What is the first intermediate host of trematodes?
snail
what is the second intermediate host of trematodes?
fish
what is the infective stage of trematodes?
metacercaria
Where does asexual reproduction of trematodes occur?
snails
What are the characteristics of Class Cestoidea (tapeworms)?
1) segmented body
2) lack a digestive tract
3) heteroxenous life cycle
What is the definitive host of tapeworms?
humans
what stage and where in the human body are tapeworms found as the definitive host?
stage –> adult tapeworms
location –> small intestine
what stage and where in the human body are tapeworms found as the intermediate/paratenic host?
stage –> larvae
location –> internal organs
What is the intermediate/paratenic host of tapeworms?
humans
What class of Platyhelminthes is mostly free living?
Class Turbellaria
What are the general characteristics of Platyhelminthes?
1) flattened dorso-ventrally –> flatworms
2) acoelomates –> no body cavity + has parenchymal cells
3) Osmoregulation –> flame cell system
4) tegument (in parasitic) –> featureless
5) 2 types of reproductive systems –> monecious + dioecious
6) ovum (egg) –> contains first larva stage
7) miracidium –> develops within egg
what are parenchymal cells?
packing tissue around organs
What is the point of the flame cell system (osmoregulation)?
to remove water
Describe monecious.
reproductive organs of male and female in one organism –> hermaphroditic
Describe dioecious.
separate male and female worms
What species is non-operculated?
schistosomes
What are the characteristics of the miracidium life stage?
- hatches in water (or snail gut)
- swims with ciliated
- positive phototaxis (may have eyespots)
How do you get swimmer’s itch?
wading in infected waters
About how many cases per year are there of swimmer’s itch?
400,000
What is the life cycle of the fluke in swimmer’s itch?
1) eggs are passes in feces
2) eggs hatch + liberate miracidia
3) develops in a molluscan (snail) intermediate host
4) humans are exposed to the dermatitis-producing cercariae
Who is the “father of tropical medicine” + discovered Schistosomes?
Manson
what is the shape of most tapeworms?
leaf-like
What are the drugs to treat flukes and tapeworms?
- Praziquantel
- Oxamniquine,
- Metrifonate
- niclosamide
what is protonephridia?
flame cell system
what is an example of degeneration?
B12 deficiency from fish tapeworms
Describe the differences between monogenea and digenea.
Digenea (flukes) :
- complex life cycle involving multiple hosts - possess two suckers, one oral and one ventral, which they use to attach to their hosts
Monogenea:
- simpler parasites
direct life cycle with only one host.
Describe the differences between cestodes and trematodes?
Cestodes:
- tapeworms
- segmented plane
- no digestive tract
- hermaphrodites
Trematodes:
- flukes
- unsegmented plane
- incomplete digestive tract
- hermaphrodites –> except schistosomas
