Parasitology - Trematodes, Cestodes

Question 1

what are trematodes

Answer 1

flukes

non-segmented flatworms

Question 2

what are fluke characteristics

Answer 2

• have ventral and oral suckers
• no body cavity
• blind ended GI tract

Question 3

what are diagenetic trematodes

Answer 3

trematodes that have two parasitic forms
1. asexual repro of sporocysts in mollusks
2. sexual repro in the definitive host

Question 4

what intermediate host is required for trematodes

Answer 4

snails or slugs

Question 5

what kind of environment do trematodes exist in

Answer 5

aquatic/wet environments

Question 6

general trematode life cycle

Answer 6

egg –> miracidium –> sporocyst –> cercaria –> metacercaria

1. eggs shed in feces
2. miracidium hatches; free swimming and burrows into bottom of snail/slug
3. sporocyst forms in the snail/slug and undergoes asexual repro
4. cercaria exits the snail/slug into the water
5. metacercaria encysts on vegetation or inside a 2nd intermediate host

Question 7

what are the major fluke parasites

Answer 7

• fasciola hepatica
• fascioloides magna
• paramphistomum
• paragonimus kellicotti
• schistosomes

Question 8

what is unique about schistomes

Answer 8

intravascular flukes

NOT hermaphroditic - have separate sexes

Question 9

what are acanthocephala

Answer 9

non segmented worms with an armed head
- allows them to burrow into host

Question 10

what is the intermediate host for acanthocephala

Answer 10

arthropods

Question 11

what species do acanthocephala infect

Answer 11

pigs, dogs, cats

Question 12

what are cestodes

Answer 12

tapeworms

segmented flatworms

Question 13

strobilus

Answer 13

the segmented part of the body consisting of a long chain of proglottids

Question 14

proglottids

Answer 14

segments that each contain a complete reproductive system

Question 15

scolex

Answer 15

head

can have suckers, hooks, or both

Question 16

what are cestode characteristics

Answer 16

• no body cavity or GIT
• hermaphroditic
• larvae type depends on cestode species
• adults live in host’s GIT
• larvae live in various host tissues

Question 17

what are the different types of cestode larvae

Answer 17

• plerocercoid/spargana
• strobilocercus
• cysticercoid
• tetrathyridia

Question 18

plerocercoid/spargana larvae

Answer 18

simplest form

• unsegmented with no bladder
• simple scolex

usually have aquatic intermediate hosts

Question 19

strobilocercus larve

Answer 19

2nd simplest

• has a small, caudal bladder
• simple scolex

Question 20

cysticercoid

Answer 20

bladder like larvae with internal scolex/scolices

three types:
- cysticercus
- coenurus
- hydatid

Question 21

cysticercus

Answer 21

one bladder with single invagination and scolex

Question 22

coenurus

Answer 22

one bladder with multiple invaginations, each containing one scolex

Question 23

hydatid

Answer 23

brood capsules form within bladder; multiple invaginations with multiple scolices each

Question 24

what cestode species have cysticercoid larvae

Answer 24

• taenia
• mesocestoides
• echinococcus

Question 25

tetrathyridia larvae

Answer 25

most complex larvae

• widened anterior end with invaginated scolex
• replicates asexually
• no bladder

Question 26

what cestode species have tetrathyridia larvae

Answer 26

mesocestoides

Question 27

what are the major cestode parasites

Answer 27

• dipylidium caninum
• taenia
• mesocestoides
• echinococcus
• anoplocephala
• moniezia