Cestodes- rest of them

Question 1

What are distinguishing characteristics of the Hymenolepidae family of cestodes?

Answer 1

proglottids are wider than long
mature proglottids only have 3-4 testes
gravid proglottids disintegrate and release eggs in host
intermediate hosts are invertebrates

Question 2

What are the two Hymenolepidae species that affect humans?

Answer 2

Hymenolepis nana and Hymenolepis diminuta

Question 3

What is the distribution of Hymenolepis nana?

Answer 3

dwarf tapeworm is worldwide, affects mostly children

Question 4

What is particular of the Hymenolepis nana hosts?

Answer 4

rodents are reservoir hosts, they do not necessarily require an intermediate host to complete their life cycle

Question 5

How can Hymenolepis nana be physically distinguished?

Answer 5

has 150-200 proglottids,
scolex has four suckers and a single row of hooks
15-45mm long (small)

Question 6

What is the distribution of Hymenolepis diminuta?

Answer 6

worldwide, mostly affects children

Question 7

How can Hymenolepis diminuta be physically distinguished?

Answer 7

20-60cm long (small)

scolex has 4 suckers and no hooks

Question 8

What are the reservoir hosts of Hymenolepis diminuta?

Answer 8

dogs, cats, any rodents, others

Question 9

What are distinguishing features of Dipylidium caninum (aka double-pored dog tapeworm)?

Answer 9

proglottids have genital pores on each side
uterus breaks down into egg capsules, each with several eggs. egg capsules released when in external environment
scolex has rostellum with four rows of hooks and four suckers

Question 10

What are the hosts of Dipylidium caninum?

Answer 10

definitive: dogs, cats, foxes, humans (children)
intermediate: cat/dog flea

Question 11

What are some defining characteristics of the order Pseudophyllidea?

Answer 11

• scolex has two grooves (bothria), which are slit-like adhesive organs
• separate male and female genital pores, located mid-ventrally on each proglottid
• testes scattered throughout the proglottid
• gravid proglottids remain attached and secrete eggs through the uterine pore

Question 12

What are the hosts of worms of the order Pseudophyllidea?

Answer 12

first intermediate host: copepod
second intermediate host: fish/amphibian
definitive host: fish-eating mammal

Question 13

What is the distribution of the Pseudophyllidea order?

Answer 13

worldwide but more in northern hemisphere

Great Lakes area in North America, Finland in Europe (eat a lot of pickled fish)

Question 14

What are the definitive hosts for Diphyllobothrium latum (broad fish tapeworm)?

Answer 14

bears (mostly), dogs, cats, foxes, mink, raccoon, walrus, seals, humans
second intermediate host: fish from Great Lakes

Question 15

What does Diphyllobothrium latum have an affinity for?

Answer 15

B12, have a receptor on their tegument. affects DNA synthesis, fatty acid synthesis, and energy production of host

Question 16

Describe the characteristics of the Diphyllobothrium latum eggs

Answer 16

oval or ellipsoidal in shape, possibly inconspicuous operculum and a nob at the opposite end, eggs pass in the stool unembryonated

Question 17

Describe the body morphology of Diphyllobothrium latum

Answer 17

scolex has bothrium, proglottids are wider than long, genital pores are located mid-ventrally

Question 18

What are the hosts of Spirometra mansonoides?

Answer 18

definitive: dogs, cats, birds, wild carnivores
accidental: humans
first intermediate: copepods and other freshwater crustaceans
second intermediate & reservoirs: birds, reptiles, amphibians

Question 19

What is the distribution of Spirometra mansonoides?

Answer 19

worldwide, but more human cases in southeast Asian countries. animal cases are endemic in North America

Question 20

What disease does Spirometra mansonoides infection cause and what does it do?

Answer 20

sparganosis. can either be due to Spirometra mansonoides infection migrating to brain (cerebral sparganosis) or by migration to the eyes (ocular sparganosis)

Question 21

Which drugs can be used as antihelminthes?

Answer 21

praziquantel, niclosamide, and albendazole.

can be used to kill adults and eggs in one dose, but specifically targets adult worms

Question 22

What does praziquantel do?

Answer 22

used for flat worms and also trematodes.
increases worm membrane permeability to calcium ions, which causes them to contract and become paralysed. the body can then digest them, so they are not seen in feces

Question 23

What does niclosamide do?

Answer 23

used specifically for tapeworms, does not affect pinworms or roundworms.
only effective against adult cestodes, thought to block ATP production by uncoupling oxidative phosphorylation

Question 24

What does albendazole do?

Answer 24

effective against roundworms, tapeworms and flukes. First treatment used in Echinococcus granulosus infections

in the benzimidazole family of drugs. binds beta-tubulin, preventing its polymerization with alpha-tubulin to synthesize microtubules. This causes reduction of glucose uptake and depletes the glycogen stores of the parasite