Cestodes: Cyclophyllidea & Pseudophyllidea

Question 1

What cyclophyllidean metacestode stage develops in an invertebrate IH? Give a species example.

Answer 1

cysticercoid (ex: hymenolepis nana)

Question 2

What are the major morphological features of cyclophyllidea?

Answer 2

1. acetabulate scolex 2. compact vitelline gland 3. apolysis

Question 3

What 3 metacestode stages occur in vertebrate intermediate hosts?

Answer 3

1. eggs eaten by vertebrate 2. cysticerus 3. ceonurus

Question 4

Trace the path in the IH from egg to metacestode.

Answer 4

1. adult worm in DH intestine 2. eggs passed in DH feces 3. eggs eaten by IH 4. develops into metacestode

Question 5

Does a cysticerus have a scolex?

Answer 5

yes single scolex

Question 6

Is the body of a cysticerus solid?

Answer 6

fluid filled sac

Question 7

What is an example of a cysticerus?

Answer 7

Taenia solium & T. sasinata

Question 8

In what genus does a hydatid development occur?

Answer 8

echinococcus

Question 9

What are the two type of hydatid cysts? In which species does each occur?

Answer 9

1. unilocular cyst in E. granulosis (endogenous budding) 2. multilocular (alveolar) cyst (exogenous budding) in E. multilocular

Question 10

What is the common name of Taenia solium?

Answer 10

pork tapeworm

Question 11

What are the intermediate & definitive hosts of Taenia solium?

Answer 11

IH = pig (ingests eggs) DH = human (ingests cysticerus)

Question 12

What is the structure of the ovary & how many testes are found in the mature proglottid of Taenia solium?

Answer 12

trilobed ovary. 150-200 testes

Question 13

How many lateral uterine branches are found in the gravid proglottid of Taenia solium?

Answer 13

7-13

Question 14

What pathology is caused by Taenia solium?

Answer 14

often asymptomatic

Question 15

What has happened to the human in cysticercosis?

Answer 15

human becomes IH by ingesting eggs & onchosphere penetrates intestine

Question 16

What is the collagenous capsule?

Answer 16

capsule that forms around cysticerus as part of host immune response may be asymptomatic

Question 17

What is a space occupying lesion?

Answer 17

pressure on host tissue. decreased circulation -> necrosis

Question 18

In what parts of the body does disseminated cysticercosis occur?

Answer 18

viscera, muscle, subcuntaneous

Question 19

What pathology can occurs in cases of ocular cysticercosis & neurocysticercosis?

Answer 19

blindness & adult onset epilepsy

Question 20

What are the three most common mechanisms by which cysticercosis occurs?

Answer 20

1. self-inflection (hand to mouth) 2. environmental contamination 3. internal autoinfection (reinfection by parasite w/o it leaving host)

Question 21

How can infections with the adult Taenia solium worm & cysticercosis be diagnosed?

Answer 21

1. MRI scans 2. surgery & ID

Question 22

How are infections with the adult Taenia solium and cysticercosis treated? What are the mechanisms of action of the drugs?

Answer 22

surgery. mechanism of drugs = anti inflammatory

Question 23

How can Taenia solium infection be controlled?

Answer 23

1. sanitation 2. good hygiene 3. meat inspection 4. cook/freeze meat

Question 24

How can meat be inspected for infection?

Answer 24

tongue of pig

Question 25

How can meat be prepared to minimize the chance of infection?

Answer 25

cook over 65 degrees C or freeze at -10 degrees C for 14 days

Question 26

What is the common name of Taenia saginata?

Answer 26

beef tapeworms

Question 27

What are the intermediate & definitive hosts?

Answer 27

IH = cattle DH = humans

Question 28

What does the egg of Taenia saginata look like?

Answer 28

identical to T. solium

Question 29

Compare mature and gravid proglottids of Taenia saginata & T. solium.

Answer 29

mature: bilobed overy w/ 300-400 testes gravid: 15-20 lateral uterine branches

Question 30

What are the symptoms generally associated w/ Taenia saginata infection?

Answer 30

most asymptomatic no cysticercosis

Question 31

What is the treatment for Taenia saginata infection?

Answer 31

PZQ & niclosamide

Question 32

How can Taenia saginata infection be controlled?

Answer 32

1. sanitaiton 2. cook/freeze

Question 33

Would you expect to find viable cysticerci in either rare, medium, or well done beef?

Answer 33

rare: 100% viable medium: 50-60% viable well: 0% viable

Question 34

What is the definitive host for Echinococcus spp?

Answer 34

herbivores: sheep & cattle

Question 35

How can humans get involved in the Echinococcus life cycle?

Answer 35

humans are never DHs but they can become IHs

Question 36

Describe the scolex morphology and proglottids in Echinococcus species.

Answer 36

scolex: acetabulate & 3 proglottids

Question 37

How does hydatidosis develop in a human?

Answer 37

human ingests eggs and becomes IH

Question 38

What type of pathology can a hydatid cause?

Answer 38

1. cycstic echinococcosis: space occupying lesion fluid leaks from cyst & into host tissue 2. alveolar echinococcocsis - cyst metastatic

Question 39

What can happen if fluid leaks from the cyst?

Answer 39

host tissue is hypersensitized & can lead to anaphylaxis

Question 40

Why is this important during surgical removal of the cyst?

Answer 40

not to nick the cyst

Question 41

What is an osseous cyst?

Answer 41

space occupying lesion

Question 42

What is the treatment for hydatidosis?

Answer 42

surgery or PAIR procedure (for inoperable cysts)

Question 43

Describe the steps in the PAIR procedure.

Answer 43

1. percutaneous Puncture of cyst 2. Aspiration of cyst fluid 3. replacement of cyst fluid w/ Injection of ethanol (kills germinal layer) 4. Reaspiration of ethanol 5. repeat 6. fill cyst w/ isotonic sodium chloride solution

Question 44

What is the common name of Hymenolepis nana?

Answer 44

dwarf tapeworm

Question 45

Does this Hymenolepis nana normally cause pathology in the human host?

Answer 45

very rare

Question 46

Draw out life cycle of Hymenolepis nana.

Answer 46

answer questions in review packet

Question 47

What is Diphyllobothrium latum's common name?

Answer 47

broad fish tapeworm

Question 48

What happens when the Diphyllobothrium latum egg hatches?

Answer 48

1. anapolysis 2. operculum

Question 49

What are the first and second intermediate hosts in Diphyllobothrium latum?

Answer 49

1st IH: coracidium in microcrustacean (copepod) 2nd IH: fish (goes into skeletal muscle but doesn't undergo further development)

Question 50

How does a definitive host become infected in Diphyllobothrium latum? What stage is infective to the DH?

Answer 50

eats 2nd IH (fish) not effective if fish is cooked. plercocercoid is infective stage

Question 51

How long can a D. latum adult worm get?

Answer 51

up to 10m

Question 52

What structures are found on the scolex of D.latum?

Answer 52

scolex: 2 bothria & proglotids

Question 53

Where is the genital pore found on adult D.latum?

Answer 53

midventrally

Question 54

Where does the uterine pore open on adult D.latum?

Answer 54

midventrally

Question 55

What is the appearance of the uterus in a gravid proglottid on adult D.latum?

Answer 55

many loops "rosette"

Question 56

Where in the world is infection with D. latum most common?

Answer 56

Scandinavia & US Great Lakes

Question 57

What are some of the vague symptoms associated with D. latum infection?

Answer 57

?

Question 58

What is the function of Intrinsic Factor?

Answer 58

binds to B12 and allows host to absorb B12 which is needed to synthesize Hb

Question 59

What is pernicious anemia? How is this caused by D. latum?

Answer 59

bone marrow produces unsually large, abnormal, immature, RBCs (megaloblasts). tape worm secretes substances which block IF from binding to vit B12 which prevents Hb synthesis (worm absorbs B12)

Question 60

How is D. latum infection diagnosed?

Answer 60

eggs in feces

Question 61

How is D. latum infection treated?

Answer 61

PZQ, niclosamide, Vit B12

Question 62

What genus causes sparganosis?

Answer 62

pseudophyllideaus

Question 63

With which stage is the human infected with sparganosis?

Answer 63

larval

Question 64

What are the three ways a person can become infected with sparganosis?

Answer 64

1. drinks H2O that contains copepods infected w/ procercoid 2. ingest uncooked animal w/ plerocercoid (frog, snakes, birds) 3. physical contact w/ percocercoid (frog flesh or poultice)