Cestodes (Flatworms)

Question 1

What is the phylum of cestodes and trematodes?

Answer 1

Platyhelminthes

Question 2

Do Platyhelminthes have a body cavity?

Answer 2

no

Question 3

2 subclasses of cestodes?

Answer 3

Eucestoda (true tapeworms)

Cotyloda (pseudotapeworms)

Question 4

Is life cycle of tapeworm always direct or indirect?

Answer 4

indirect

Question 5

How many intermediate hosts to tapeworms require?

Answer 5

one or two

Question 6

What are the intermediate hosts of tapeworms?

Answer 6

arthropods
fish
mammals

Question 7

Are domestic animals intermediate or definitive hosts of tapeworms?

Answer 7

intermediate
definitive, or
both

Question 8

What are larval stages of domestic animal tapeworms called?

Answer 8

bladderworms

Question 9

What path do bladderworms take after ingested by definitive host?

Answer 9

released from tissue of intermediate host and develop into adult tapeworms within digestive tract of definitive host.

Question 10

What are the solid bodied cestodes?

Answer 10

procercoid
plerocercoid
tetrathyridium

Question 11

How do domestic animals become infected with larval stages of tapeworms?

Answer 11

Ingestion of cestode egg or procercoid

Question 12

Body of tapeworm?

Answer 12

long
dorsoventrally flattened
3 regions
scolex: head modified into attachment organ and
bears 2 to 4 muscular suckers (acetabula)
rostellum is snout, fixed or retractable, may
have hooks
strobila: the body composed of segments
(proglottids) in diff stages of maturity
proglottids near neck = immature, then
sexually mature proglottids, then gravid
segments that contain eggs

Question 13

Which part of eucestodes breaks off its body and passes out of definitive host in feces?

Answer 13

gravid proglottids

Question 14

How do cestodes get nutrients?

Answer 14

nutrients absorbed directly through body wall

Question 15

Which organs occur in each individual proglottid of cestodes?

Answer 15

both male and female reproductive organs

Question 16

How do cestodes reproduce?

Answer 16

cross-fertilization

self-fertilization

Question 17

Cestode egg?

Answer 17

contains fully developed embryo (has six hooks in three pairs) = hexacanth embryo or oncosphere

Question 18

Life cycle of cestode?

Answer 18

gravid proglottid shed fully intact in feces (singly or in chains)
they then rupture and release eggs
eggs ingested by intermediate host
develop into metacestode stage
metacestode (larval) stage may be in the form of a cysticercus, a coenurus cyst, a hydiatid cyst, or a tetrathyridium
definitive host becomes infected after ingestion of an intermediate host that contains metacestode stage
juvenile tapeworm then emerges from metacestode stage, attaches to lining of small intestine, and begins to produce strobili.

Question 19

How do pseudotapeworms differ from true tapeworms?

Answer 19

reproductive organs and genital pores centrally located rather than laterally located.

Question 20

What are bothria?

Answer 20

organs of attachment
pair of slitlike organs
located on lateral aspect of scolex

Question 21

Eggs of pseudotapeworms?

Answer 21

operculated
released from uterus
passed in feces
contain coracidium (embryo)

Question 22

Life cycle of pseudotapeworm?

Answer 22

released when egg contacts water
coracidium ingested by microscopic aquatic crustacean
develops into stage called a procercoid
crustacean ingested by fish or amphibian
develops into metacestode stage (i.e., plerocercoid or sparganum) within muscle of host
definitive host becomes infected after ingesting second intermediate host

Question 23

What is the most common eucestode of dogs and cats?

Answer 23

Dipylidium caninum

Question 24

How dogs and cats become infected with Dipylidium caninum?

Answer 24

ingestion of intermediate host flea

Question 25

What do Dipylidium caninum proglottids contain?

Answer 25

thousands of unique egg packets containing 20 to 30 hexacanth embryos

Question 26

Prepatent period of Dipylidium caninum?

Answer 26

14 to 21 days

Question 27

What are the 3 canine taeniid tapeworms?

Answer 27

Taenia pisiformis Taenia hydatigena Taenia ovis

Question 28

Where do canine taeniid tapeworms show up?

Answer 28

motile, terminal, gravid proglottids on feces, coat, or in bedding of host

Question 29

How do dogs become infected with taeniid tapeworms?

Answer 29

ingestion of cysticercus-infected intermediate host

Question 30

Intermediate hosts of Taenia pisiformis?

Answer 30

rabbits | hares

Question 31

Eggs of taenid tapeworms?

Answer 31

slightly oval 43um to 53um by 43um to 49um (Taenia pisiformis) 36um to 39um by 31um to 35um (Taenia hydatigena) 19um to 31um by 24um to 26um (Taenia ovis) contain oncosphere (hexacanth embryos) with 3 pairs of hooks similar to Echinococcus species

Question 32

What are the 2 Multicep species of tapeworms found in dogs?

Answer 32

Multiceps multiceps | Multiceps serialis

Question 33

What is the hydatid cyst tapeworm of dogs?

Answer 33

Echinococcus granulosus

Question 34

What is the hydatid cyst tapeworm of cats?

Answer 34

Echinococcus multilocularis

Question 35

Why are the Echinococcus species important?

Answer 35

extreme zoonotic potential

Question 36

Eggs of Echinococcus granulosus?

Answer 36

ovoid 32um to 36um by 25um to 30um contains single oncosphere w 3 pairs of hooks

Question 37

Eggs of Echinococcus multilocularis

Answer 37

ovoid | 30um to 40um

Question 38

Adult Echinococcus?

Answer 38

``` tiny (1.2um to 7.0um length) 3 proglottids (immature, mature, gravid) proglottids so tiny, often overlooked by client, vet tech, veterinarian when passed in feces ```

Question 39

Diagnosis of Echinococcus infection?

Answer 39

identification of adult taken from host's intestinal tract antemortem diagnosis accompanied by purging the dog or cat with arecoline hydrobromide per os at 3.5 mg/kg and collecting the feces. (only when infection strongly suspected) caution with handling because of zoonosis

Question 40

Can humans be intermediate hosts to hydatid cysts of Echinococcus species?

Answer 40

Yes | They can develop in variety of organs in humans

Question 41

What are the 3 equine tapeworms?

Answer 41

Anoplocephala perfoliata Anoplocephala magna Paranoplocephala mamillana

Question 42

Where is Anoplocephala perfoliata found in horses?

Answer 42

small intestines large intestines cecum

Question 43

Where is Anoplocephala magna found in horses?

Answer 43

small intestine | occasionally stomach

Question 44

Where is Paranoplocephala mamillana found in horses?

Answer 44

small intestine | occasionally stomach

Question 45

Eggs of Anoplocephala perfoliata?

Answer 45

thick walls one or more flattened sides 65um to 80um diameter

Question 46

Eggs of Anoplocephala magna?

Answer 46

slightly smaller than perfoliata thick walls 50 to 60um