Lecture 5 Parasite diversity 4 Trematodes Flashcards
Describe Phylum Platyhelminthes.
- macroparasites
• 3 parasite classes
• dorso-ventrally
flattened bodies
Describe class trematoda in Phylum Platyhelminthes.
-flukes
-endoparasites
–>every infect class of vertebrates
• members: 3 subclasses
What is a subclass of of Class Trematoda in Phylum Platyhelminthes.
Digenea
Describe subclass Digenea in class trematoda in Phylum Platyhelminthes (kind of life cycle, kind of reproduction, type of hosts, intermediate hosts?)
-complex life cycles
–>alternating sexual & asexual stages
–>intermediate & final/definitive hosts
final host
• variations on life cycle
—–>2 or more 2nd
intermediate hosts
—–>no 2nd intermediate
Describe life cycle of subclass Digenea in class trematoda in Phylum Platyhelminthes. (include hosts, reproductive stages, transmission, final/intermediate hosts)
Definitive host: predatory fish/human have flukes that (sexual reproduce) -> egg
- > (hatch)-> miracidium -> (infection in first intermediate host; snail) -> miracidium (transformation)-> sporocyst-> (asexual reproduction)-> rediae-> (pooped)
- > free-swimming cercariae-> (attach to second intermediate host fish & encyst) -> Metacercariae -> eaten by final host human/predatory fish flukes (trophic transmission)
Describe morphology of subclass Digenea in class trematoda in Phylum Platyhelminthes.
much variation -> key to spp id
suckers: oral and ventral (adhesion) in adults all ventral
reproductive organs: ovary, testes, vitellarium (monicious)
Describe Haematoloechus spp of Trematode.
-frog lung fluke
• larval insect 2nd
intermediate host
• dozens in lungs!
Describe Alaria spp. of Trematode
- mostly canid(canine) final hosts • sometimes paratenic (beside) hosts involved • no \_\_metacercariae_ but has mesocercaria -->unusual stage
Describe Ribeiroia ondatrae of Trematode.
• associated with most amphibian malformations
—>greatly increased reports
Ribeiroia ondatrae and ambhibian malformation - Why might this reflect a parasite strategy?
cercarian burow in hind limbs to get itself transmitted so now the frog is slower. Malformed legs fared worst.
Describe Euhaplorchis californiensis of Trematode.
marine trematode
-cysts form in fish brain
-swim on side in top of water
site choice for parasite: brain increase/decrease? serotonin activity acted weird
Describe Dicrocoelium dendriticum of Trematode.
-many alterations - ant behaviour weird
Describe Fasciola spp. of Trematode.
• very large adults in liver
• no 2nd intermediate host
—>common zoonotic (transmits/infect from animals to humans)
Describe Halipegus eccentricus of Trematode.
potentially 4 hosts in life cycle!
Why care about the trematodes?
- importance to amphibian
* aquatic fisheries importance • importance for human health (shistosomiasis)
trematode Schistosoma spp.
-3 species infecting humans
• no 2nd intermediate host
—>no metacercariae
• paired adult worms reproduction
what are the 3 main species infecting humans
3 main species infecting humans:
- > S. mansoni – large intestine portal veins
- -> S. haematobium – venous plexus veins
- ->S. japonicum – small intestine veins
id. via shape/size
What and name event when the pathology of
S. haematobium was discovered ?
Pathology:
• S. haematobium & S. mansoni
—>Napoleon’s army in Egypt
what is major source of pathology
bladder and splien pulmonary/portal veins - blood shunting somach is extended -normal adult worm development _decreased_ host immune system cues But.... As long as 30 years! • _decrease_ of host immune system -no antibiotics ---mechanism unknown
So how can we control
schistosomiasis?
Challenges to consider:
• ease of transmission
–final & intermediate hosts persistence
– ________________
basic strategies: selective recombinant production -> vaccinate animals
