Parasitology - Trematodes, Cestodes Flashcards
what are trematodes
flukes
non-segmented flatworms
what are fluke characteristics
- have ventral and oral suckers
- no body cavity
- blind ended GI tract
what are diagenetic trematodes
trematodes that have two parasitic forms
1. asexual repro of sporocysts in mollusks
2. sexual repro in the definitive host
what intermediate host is required for trematodes
snails or slugs
what kind of environment do trematodes exist in
aquatic/wet environments
general trematode life cycle
egg –> miracidium –> sporocyst –> cercaria –> metacercaria
- eggs shed in feces
- miracidium hatches; free swimming and burrows into bottom of snail/slug
- sporocyst forms in the snail/slug and undergoes asexual repro
- cercaria exits the snail/slug into the water
- metacercaria encysts on vegetation or inside a 2nd intermediate host
what are the major fluke parasites
- fasciola hepatica
- fascioloides magna
- paramphistomum
- paragonimus kellicotti
- schistosomes
what is unique about schistomes
intravascular flukes
NOT hermaphroditic - have separate sexes
what are acanthocephala
non segmented worms with an armed head
- allows them to burrow into host
what is the intermediate host for acanthocephala
arthropods
what species do acanthocephala infect
pigs, dogs, cats
what are cestodes
tapeworms
segmented flatworms
strobilus
the segmented part of the body consisting of a long chain of proglottids
proglottids
segments that each contain a complete reproductive system
scolex
head
can have suckers, hooks, or both
what are cestode characteristics
- no body cavity or GIT
- hermaphroditic
- larvae type depends on cestode species
- adults live in host’s GIT
- larvae live in various host tissues
what are the different types of cestode larvae
- plerocercoid/spargana
- strobilocercus
- cysticercoid
- tetrathyridia
plerocercoid/spargana larvae
simplest form
- unsegmented with no bladder
- simple scolex
usually have aquatic intermediate hosts
strobilocercus larve
2nd simplest
- has a small, caudal bladder
- simple scolex
cysticercoid
bladder like larvae with internal scolex/scolices
three types:
- cysticercus
- coenurus
- hydatid
cysticercus
one bladder with single invagination and scolex
coenurus
one bladder with multiple invaginations, each containing one scolex
hydatid
brood capsules form within bladder; multiple invaginations with multiple scolices each
what cestode species have cysticercoid larvae
- taenia
- mesocestoides
- echinococcus
tetrathyridia larvae
most complex larvae
- widened anterior end with invaginated scolex
- replicates asexually
- no bladder
what cestode species have tetrathyridia larvae
mesocestoides
what are the major cestode parasites
- dipylidium caninum
- taenia
- mesocestoides
- echinococcus
- anoplocephala
- moniezia
