Tapeworms- Dogs and Cats

Question 1

Describe the general life cycle of tapeworms

Answer 1

• Adults in the small intestine
• Proglottids break off
• Egg/proglottids shed in faeces
• Eggs immediately infective
• Eggs eaten by intermediated host
• Metacestode develops in intermediate host
• Metacestode eaten by definitive host
• Adult tapeworm develops in small intestine

Question 2

What are the 4 types of metacestodes found in intermediate hosts?

Answer 2

Cysticerus- single envaginated protoscolex

Coenurus- complex, several protoscolices

Cysticercoid- microscopic, single protoscolex found in invertebrae intemediate host

Hyatid- highly complex, numerous protoscolices potential for metastasis

Question 3

What are the 5 species of taenia in which dogs are the definitive host?

Answer 3

Taenia ovis

Taenia hydatigena

Taenia multiceps

Taenia pisiformis

Taenia serialis

Question 5

What are the two species of echinococcus that dogs are the definitive host of?

Answer 5

Echinococcus granulosus

Echinococcus multiocularis

Question 6

What is the species of dipylidium that has dogs as its definitive host?

Answer 6

Dipylidium caninum

Question 7

Where are taenia spp founf?

What size are normal taenia- what do they sometomes have?

What is their pre-patent period and patency?

Answer 7

Adult worms found in the small intestine

Large- 30cm-5m with or without armed rostellum

The pre-patent period is 4-10 weeks

Patency is months-years

Question 8

What species of tapeworms eggs is this?

Answer 8

Characteristic eggs- thick embryophore, hexacanth embryo

40um in diameter

Taenia spp

Question 9

What are the intermediate hosts of T. ovis, T. hydatigena, T. multiceps?

What are the intermediate hosts of T. pisiformis and T. Serialis?

Answer 9

T. Ovis, T. hydatigena, T. multiceps- sheep

T. pisiformis, T. serioalis- rabbit

Question 10

What does this image show?

Answer 10

Cysticercus in muscles of Taenia ovis- sheep measles

Adult tapeworm 1.2-1.5m

Question 11

What tapeworm does the following image show?

Answer 11

Taenia hydatigena

Cysticercus in peritoneum of sheep- grapes

Thin-necked bladder worm

Liver-liver capsule-peritoneum

Adult tapeworm- 1m

Question 12

What tapeworm can be diagnosed from the following image?

Answer 12

Taenia multiceps

Coenurus in brain

Gid cyst- neurological disease

Space occupying cyst in CNS

Leads to circling, head pressing and tilting

Adult tapeworm- 1.2m

Question 13

This was found in a rabbit, what is the species of tapeworm and how long would the adult tapeworm be?

Answer 13

Taenia pisiformis- rabbit is intermediate

Cysticercus in peritoneum

Adult tapeworm- 2m

Question 14

What intermediate host would this be found in?

What species of tapeworm is it and what size is the adult?

Answer 14

Rabbit- coenrus in connective tissue/sub-cutaneous

Taenia serialis

Adult tapeworm 5m

Question 15

What is the intermediate host for Taenia taeniaeformis?

Where is it found in the intermediate host?

What is the PPP?

Answer 15

Intermediate host- mouse

Found as cysticercus in the liver

PPP- 4 weeks

Question 16

How can a taenia taeniaeformis tapeworm be identified?

Answer 16

Adult is 60cm and has typical bell shaped protoglottids

In a cat

Question 17

What symptoms do taenia spp cause?

How is its diagnosed, treated and controlled?

Answer 17

Disease- rarely associated with clinical signs, anal pruitus

Diagnosis- faecal sample- eggs or proglottids- 10g, sampling on 3 consecutive days

Treatment and control-
Praziquantel treatment to remove adult tapeworm (treatment interval dictated by PPP)
Break the life cycle through controlling access to intermediate host/metacestode stage

Question 18

Where is dipylidium caninum found in the final host?

What is its intermediate host?

What is the size of an adult?

Answer 18

Found in the small intestine of dogs and cats

Intermediate hosts are:
Ctenocephalides felis- flea
Trichodected canis- canine chewing lice

Adult- 50cm

Question 19

What is the anterior end of a tapeworm called?

Answer 19

Scolex

Question 20

What can be found on a dipylidium caninum scolex?

What do their gravid segments loos like?

Answer 20

4 unarmed suckers

Protrusable rostellum bearing 4-7 rows of small hooks

Gravid segments are barrel shaped (rice grains) with 2 genital pores on each proglottid

Question 21

What species of tapeworm are these eggs from?

Answer 21

Dipylidium caninum

each egg capsule containing 10-15 eggs

Question 22

Describe the life cycle of D. caninum

Answer 22

Adult tapeworm in small intestine of cat/dog- PPP- 3 weeks

Actively motile proglottis are passed in faeces
Disintegrate and eggs released

Eggs eated by flea larvae on floors, carpets, nooks etc
Oncospheres hatch and develop into cysticercoids in body cavity of adult flea

Infected adult flea earten as animal grooms

Question 23

Describe the pathogenesis and control of D. caninum

Answer 23

• Very little pathogenesis and rarely any disease
• Crawling, motile proglottids can be irritating
• Owners distressed by presence of motile proglottids
• Gravid proglottids- white, rice grains/cucumber seeds
• Treatment using praziquantel and flea control

Question 24

What is the definitive host and intermediate hosts of echinococcus granulosus

Answer 24

Definitive host- dog- asymptomatic

Intermediate hosts- sheep and cattle

Question 25

Which Echinococcus species are zoonotic?

Answer 25

Echinoccus granulosus- severe disease

Echinococcus multilocularis- poor prognosis

Question 26

What disease can echinococcus spp cause with their metacestodes?

How do they appear slighlty differently between species?

Answer 26

Hyatid disese- hyatic cyst

Highly complex, numerous protoscolices, potential for metastasis

Echinoccous granulosis- cystic/hyatid echinococcosis

Echinococcus multilocularis- alveolar echinococcosis

Question 27

Describe an adult echinococcus and its eggs

Answer 27

Adult tapeworms:

• Very small- 5mm
• Only have three proglottids
• Final proglottis largest and gravis- shed in faeces
• Normally non-pathogenic in the dog

Eggs:

• 40um
• Thick embrophore
• Indistinguishable from Taenia eggs

Question 28

Describe the life cycle of echinococcus spp

Answer 28

• Adult in small intestine
• Embroyated egg in faeces- ingestion by intermediate host
• Oncosphere hatches- penetrates intestinal wall
• Hyatid cyst in organs- commonly liver and lung
• Protoscolex from cyst ingested
• Scolex attached to small intestine
• Possible for human to ingest embronated eggs leading to hyatid cysts in various organs

Question 29

How many species of Echinococcus granulosus sensu lato are there?

Answer 29

Origially considered 1 not split into 5 with wide host variety and zoontoic portential

Question 30

What is the definitive host of echinococcus granulosus?

Where is the adult worm found?

What are the intermediate hosts?

Where is the metacestode found?

Answer 30

Definitive host- dog

Adult worm in small intestine- no disease

Intermediate host- sheep, cattle, camels

Metacestode forms a hyatid cyts- lungs, liver can be all over

Found int UK

Question 31

Where is echinococcus multilocularis found in the world?

Answer 31

Parasite of the northern hemisphere

Present in east and central Europe

Not in the UK- surveillance present

Question 32

What is the definitive host of echinococcus multilocularis?

What is the intermediate hosts?

Where are the metacesodes in the intermediate hosts found?

Answer 32

Definitive host- fox and dog

Intermediate hosts- small mammals and rodents

Metacestodes form hyatid cytsts- small, multiocular lesions

Question 33

How are echinococcus species in dogs diagnosed, treated and controled?

Answer 33

Disease is rarely associated with clinical signs- may cause anal pruritus

Diagnosis- faecal sample- egg or proglottids
10g, sampling on 3 consecutive days

Treatment and control:
Preziquantel treatment to remove adult tapeworm (interval indicated by PPP)
Break life cylce thrugh controlling access to intermediate host/metacestode stage

Question 34

How are humans infected with Echinococcus granulosus and what are the symptoms?

Where is the infection commonly found in humans?

Answer 34

Infection by ingesting eggs from dogs in contaminated soil, water and food

Space occupying cyst forms- liver, lungs, bone marrow brain

Slow growing

Asymptomatic incubation period- several years

Symptoms- depends on the location of the cyst
Hepatic and pulmonary symptoms common
Jaundice, cholangitis, abdominal pain
Rupture of the cyst- fever, anapylactic reaction

Common in developing countries- Asia
~10 cases a year in UK

Question 36

What happens with a human case of Echinococcosis multicularis Alveolar Echinococcosis infection?

Answer 36

Very serious pathogen in humans

Large, slow growing cysts- asymptomatic incubation period of 5-15 years
tumour like lesions in the liver- metastasize and spread to the lungs and brain

Invade and destroy tissues:
Pain, weight loss, malaise, liver failure

Difficult to diagnose and treat- under reported, mortality rate 50-75%

Question 37

Where are cases of Echinococosis multilocularis alveolar echinococcosis found in the world?

Answer 37

Parasite of the northern hemisphere

Public health concern in Asia

Cases reported in Alaska and Canada

Europe- prevalence has increased

Question 38

How is Echinococcus spp in humans diagnosed, treated and controled?

Answer 38

Diagnosis:
Ultrasonography imaging and CT/MRI scans
Serology

Treatment:
Cystic echinococcosis- percutaneous treatment of the hyatid cysts with the PAIR technique, drug treatment, surgery
Alveolar echinococcosis- early diagnosis and radical surgery followed by treatment with albendazole

Control:
Controlling disease is definitive and intermediate hosts
Improved hygiene in slaughtering animals
Education programmes

Question 39

What specific features apply to tapeworms in the PET travel scheme?

Answer 39

All dogs must be treated with praziquantel 1-5 days before entry into the UK

A vet must record treatment in the animals passport

Repeat transport again 28 days after returning