Unit 4 - Cestodes Flashcards by Danica Wilson

Acoelomates have:

NO body cavity

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Describe the body shape of cestodes:

dorsoventrally flat chain of segments

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Are cestodes monoecious or dioecious?

monoecious (hermaphroditic)

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Where are the majority of cestode adults located?

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What life cycle stage of cestodes is typically not pathogenic?

adults

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The body of the cestode is called a ______ and each of the segments are _________.

strobila; proglottids

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Cestodes: direct or indirect life cycle?

indirect

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How many intermediate hosts do “true” cestodes (Order Cyclophyllidea) have?

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How many IH do “primitive” cestodes (Diphyllobothriidea) have?

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What is the Cyclophyllidea scolex?

suckers +/- hooks

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Diphyllobothriidea scolex?

Bothria (groove)

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Genital pore location for Cyclophyllidea:

lateral

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Diphyllobothriidea genital pore location:

medial (with the uterine pore)

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How are Cyclophyllidea eggs shed?

in gravid proglottids; eggs without opercullum

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How are Diphyllobothriidea eggs shed?

shed from pore in proglottids; eggs operculate

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larval cestode in IH:

metacestode

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Which stage of the cestode life cycle is more often associated with disease?

metacestodes

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How many types of metacestodes do Cyclophyllideans have?

6 types (depends on species)

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Metacestodes that develop into 1 adult in DH (only one worm is contracted):

Cysticercus
Strobilocercus
Cysticercid

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Metacestodes that develop into multiple adults in DH:

Coenurus
Unilocular hydatid cyst
Alveolar (multiocular) hydatid

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What are the two metacestode stages of Diphyllobothriideans? Which stage develops in 1st IH? 2nd IH?

Procercoid (1st IH), Plerocercoid (2nd IH)

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Each plerocercoid develops into:

1 adult cestode

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“bladder worm”

Cysticercus

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Cysts in cysts; internal budding. Thick walled and slow growing:

Unilocular hydatid cyst (endogenous)

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external budding:

alveolar (multiocular) hydatid (exogenous)

What are the two genera of importance from the Family Taeniidae?

Taenia, Echinococcus

What is the zoonotic potential of Taenia/Echinococcus?

humans may be DH or dead-end IH

DH and IH for Taenia, Echinococcus (Cyclophyllidea):

mammals (predator/prey)

DH for Taenia pisiformis:

canids

What is ingested by canids when dealing with Taenia pisiformis?

cysticercus

What is the IH for Taenia pisiformis?

rabbit

What is the DH for Taenia hydatigena?

canids

What is the IH for Taenia hydatigena?

ruminants, swine

Not as common as T. pisiformis in domestic dogs:

Taenia hydatigena

DH for Taenia taeniaeformis:

felids

IH for Taenia taeniaeformis:

rodents

larva ingested for DH infection with T. hydatigena:

cysticercus

What stage of T. taeniaeformis is ingested to cause infection in the DH?

strobilocercus

What is the general PPP for all Taenia spp.?

1.5 months

Pork tapeworm

Taenia solium

Beef tapeworm

Taenia saginata

Two Taenia spp. of public health importance:

solium, saginata

What is ingested from pork/beef meat to cause infection in humans (T. solium/saginata)?

cysticercus

Humans can be an accidental IH for which Taenia spp?

solium

Has very small adult stages but very large metacestodes:

Echinococcus spp.

Which stage of Echinococcus spp is zoonotic?

metacestodes

DH for Echinococcus granulosus:

canids

IH for Echinococcus granulosus:

primarily ungulates (humans)

What's important to note about Echinococcus granulosus eggs?

Taeniid eggs: cannot differentiate from Taenia spp

Domestic cycle of Echinococcus granulosus:

dogs (DH) --> sheep (IH)

Sylvatic cycle of Echinococcus granulosus:

1. wolf (DH) --> caribou (IH) | 2. dingo (DH) --> kangaroo (IH)

How can humans become accidentally infected with E. granulosus?

primarily by ingesting eggs while handling dogs

DH for Echinococcus multilocularis:

foxes, other canids (rarely cats)

IH for Echinococcus multilocularis:

rodents (humans)

Pathology for this helminth mimics hepatic carcinoma when it accidentally infects humans:

E. multilocularis

E. granulosus larval type:

unilocular hydatid cyst

Larval type for E. multilocularis:

multilocular (alveolar) hydatid cyst

Location of E. granulosus in IH:

liver, lung, other

Location of E. multilocularis in IH:

abdominal cavity

PPP for Echinococcus spp?

~1 month

AKA 1. Cucumber tapeworm 2. Flea tapeworm and 3. Double-pored tapeworm:

Diplydium caninum

DH for Dipylidium caninum?

felids and canids

How does the DH get infected with D. caninum?

ingestion of infected IH

What is the IH for Dipylidium caninum?

Ctenocephalides felis

Zoonotic Dipylidium spp?

caninum

Dipylidium caninum eggs appear in:

"packets"

Infective stage for Dipylidium caninum:

cysticercoid

Location of adults in DH for Anoplocephala perfoliata?

ileum; cecum; ileocecal junction

DH for Anoplocephala perfoliata?

equids

IH for Anoplocephala perfoliata:

Oribatid mites (free-living mites)

May cause pathology in DH including inflammation and ulceration:

A. perfoliata

Which species of helminths have eggs with a "pyriform" appartus?

A. perfoliata, Moniezia spp.

DH for Moniezia spp?

ruminants

Common helminth of ruminants, not considered pathogenic:

Moniezia spp

IH for Moniezia spp?

oribatid mites

Infective stage of Moniezia spp:

cysticercoid

"fringed tapeworm"

thysanosoma spp

DH for Thysanosoma spp:

small ruminants; rarely cattle and deer

IH for Thysanosoma spp:

"book lice" or "bark lice"

infective stage for Thysanosoma spp:

cystocercoid

Has egg packets similar to Dipylidium:

Thysanosoma spp

Adults are in SI, bile ducts, and pancreatic ducts:

Thysanosoma spp

Spirometra DH:

felids, canids, raccoons

PH for Spirometra:

non-fish vertebrates (2nd IH)

1st IH for Spirometra:

copepod

Where is Spirometra spp common?

southeastern US

What GI signs are adult spirometra associated with?

vomiting, diarrhea, weight loss

When the plerocercoid causes disease:

sparganosis

DH for Diphyllobothrium latum:

canids, felids, humans

PH/2nd IH for Diphyllobothrium latum:

freshwater fish

1st IH for Diphyllobothrium latum:

copepod

Geographic distribution for D. latum:

cold climates (including northern US)

PPP for spirometra spp:

10-30 days

"holdfast organ"

scolex

Causes neurocysticercosis in humans:

Taenia solium

Also known as the "sparganum"

plerocercoid

What are the adult Diphyllobothriidean cestodes that are more likely to causes disease?

- Spirometra - Diphyllobothridium - Anoplocephala perfoliata - Thysanosoma

Has dogs as the direct host with sheep as the intermediate host:

Taenia multiceps

Has dogs are the directs host with rabbits and cats as the IH:

Taenia serialis

What is the metacestode stage for both T. multiceps and T. serialis?

coenurus

Unit 4 - Cestodes Flashcards

(100 cards)