SA Cestodes

Question 1

Name the cestode life cycle stage present in the intermediate host.

Answer 1

Metacestode

Question 2

Describe the morphology of an adult cestode.

Answer 2

Segmented, proglottids showing genital pore and reproductive organs,

Question 3

Describe the morphology of a tapeworm egg.

Answer 3

Thick, brown embryophore containing the onchosphere, 40um

Question 4

Outline the general lifecycle of a cestode.

Answer 4

Adults in the small intestine shed gravid proglottids into the hosts faeces. Proglottids disintegrate and eggs are dispersed. Eggs are ingested by the host species where they develop to the metacestode. Metacestodes are ingested by the definitive host and become adults in the small intestine.

Question 5

Name four types of metacestode:

Answer 5

Cysticercus (taenia), coenurus, hydatid, cystercercoid

Question 6

Tx of adult tapeworm.

Answer 6

Praziquantel or double dose of pyrantel

Question 7

Which cestode has a cysticercus?

Answer 7

Taenia spp.

Question 8

Cysticercus of these Taenia species are found where in the sheep (IH)? Ovis, hydatigena, multiceps.

Answer 8

Ovis - muscle, hydatigena - peritoneum, multiceps - brain

Question 9

What is the intermediate hosts in a taenia lifecycle? Which species are associated with each host?

Answer 9

Sheep - ovis, hydatigena, multiceps. Rabbit - pisiformis, serialis Mouse - taeniformis

Question 10

Cysticercus of these Taenia species are found where in the rabbit (IH)? Pisiformis, serialis

Answer 10

Pisiformis - peritoneum Serialis - connective/ sub-cut tissues

Question 11

Strobilocercus of Taenia taeniformis are found where in the mouse (IH)? Which definitive host is this spp associated?

Answer 11

Liver Cats

Question 12

Which morphological feature is characteristic of Taenia taeniaformis?

Answer 12

Bell shaped proglottids

Question 13

Some taenia species posess a rostellum. What is this structure and what is its function?

Answer 13

A retractable, muscular structure located at the end of the scollex. It may possess hooks. Involved in parasite attachment to the gut wall

Question 14

True or false. Echinococcus spp. are zoonotic. Which species are relevant here, in the UK & continental EU?

Answer 14

True. UK - granulosis Rest of EU - multilocuralis

Question 15

Definitive and intermediate host of Echinococcus granulosus?

Answer 15

D - Dog I - sheep, horse, camel, human

Question 16

Name the two subspecies of Echinococcus and their intermediate hosts.

Answer 16

E. granulosus subsp granulosus - sheep, human, cattle etc E. granulosus subsp equinus - horse

Question 17

Describe the morphology of E. granulosus.

Answer 17

Small adult tapeworm - 5mm Four suckers on scolex Rostellum present

Question 18

What clinical signs are associated with human hydatid disease?

Answer 18

Slow growing, space occupying cysts of hydatids Liver - jaundice, cholangitis, abdominal pain Lung - pleurisy Anaphylaxis if rupture occurs

Question 19

Alveolar echinococcosis is cause by which Echinococcus species?

Answer 19

Echinococcus multilocularis - fox tapeworm

Question 20

Why is alveolar echinococcosis considered extremely pathogenic?

Answer 20

large, slow growing cysts difficult to diagnose and treat long incubation tume metastisize and spread

Question 21

Which areas of EU are fox tapeworm usually found?

Answer 21

East and central - increasing urban fox population in UK may lead to greater risk here.

Question 22

How long before entry into the UK must dogs receive a tapeworm treatment?

Answer 22

1-5 days

Question 23

Describe the morphology of Dipylidium caninum.

Answer 23

Adults - 50cm long 4 unarmed suckers on the scolex Protrusable armed (4-7 rows of hooks) rostellum +++ Segments Barrel shaped gravid proglottids - 10-15 eggs per egg capsule Two genital pores per PG

Question 24

Which flea species are implicated in transmission of D. caninum?

Answer 24

Ctenocephalides felis Also Trichodectes canis

Question 25

What is the pre-patent period of D. caninum?

Answer 25

4-6 weeks

Question 26

Outline the life cycle of D. caninum.

Answer 26

Adult tapeworm in the SI. Motile proglottids excreted in faeces. Eggs eaten by the flea and develop within to a cysticercoid. Infected flea is eaten as the animal grooms.

Question 27

Dipylidium are considered to show little pathogenesis. Why then are they considered?

Answer 27

Owners often find the motile proglottids very distressing to observe. Motile proglottids may cause minor irritation