Y3 Parasitology S2 > Tapeworms > Flashcards

Tapeworms Flashcards

(53 cards)

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1
Q

Tapeworms come from which group of parasites?

A

Cestodes

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2
Q

Describe the steps in the general lifecycle of tapeworms

A
  • Adults in small intestine (they have no gut so rely on host completely)
  • Proglottids break off and eggs/proglottids shed in faeces
  • Eggs immediately infective
  • Eggs eaten by intermediate host
  • Metacestode develops in intermediate host
  • Metacestode eaten by definitive host where the adult tapeworm develops in the SI
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3
Q

Name the 4 metacestode types in the intermediate host

A
  • Cysticercus
  • Coenurus
  • Cysticercoid
  • Hydatid
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4
Q

What is a cysticercus?

A

Single evaginated protoscolex

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5
Q

What is a coenurus?

A

Complex, several protoscolices, which can all potentially develop into an adult worm

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6
Q

What is a cysticercoid?

A

Microscopic, single protoscolex, found in invertebrate intermediate host

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7
Q

What is a hydatid?

A

Highly complex, numerous protoscolices, potential for metastasis to set up another hydatid cyst

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8
Q

Name the 5 species of Taenia that dogs are the definitive host of

A
  • Taenia ovis
  • Taenia hydatigena
  • Taenia multiceps
  • Taenia pisiformis
  • Taenia serialis
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9
Q

Dogs are also the definitive host of which 3 other tapeworm spp?

A
  • Echinococcus granulosus
  • Echinococcus multilocularis
  • Dipylidium caninum
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10
Q

Cats are the definitive host of which cestode?

A

Taenia taeniformis

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11
Q

Where are adult Taenia found?

A

Small intestine

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12
Q

Describe the characteristic Taenia eggs

A

Thick embryophore, hexacanth embryo, ~40μm in diameter (these eggs are also the same as Echinococcus and can’t be differentiated)

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13
Q

Describe the morphology of Taenia

A
  • Large 30cm-5m
  • +/- armed rostellum
  • Hooks and suckers
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14
Q

How long is the PPP of Taenia?

A

4-10 weeks (spp. dependent)

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15
Q

Sheep are the intermediate host of which Taenia spp?

A

Taenia ovis
Taenia multiceps
Taenia hydatigena

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16
Q

Rabbits are the intermediate host of which Taenia spp?

A

Taenia pisiformis

Taenia serialis

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17
Q

Describe the features of a Taenia ovis infection

A
  • Cysticercus in muscles
  • ‘Sheep measles’
  • Adult tapeworm is 1.2-1.5m long
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18
Q

Describe the features of a Taenia hydatigena infection

A
  • Cysticercus in peritoneum
  • Thin necked bladder worm
  • ‘Grape’ appearance
  • Adult = 1m long
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19
Q

Describe the features of a Taenia multiceps infection

A
  • Coenurus in brain
  • Gid cyst causes neurological disease
  • Space occupying CNS lesion
  • Circling, head pressing and tilting
  • Adult = 1.2m long
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20
Q

Describe the features of a Taenia pisiformis infection

A

Cysticercus in peritoneum

Adults = 2m long

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21
Q

Describe the features of a Taenia serialis infection

A
  • Coenurus in connective and sub-cutaneous tissue

- Adult = 5m long

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22
Q

What is the intermediate host of Taenia taeniformis in cats?

23
Q

Describe the features of a Taenia taeniformis infection

Study These Flashcards
A
  • Cysticercus in liver
  • Adult = 60cm, bell shaped proglottids
  • PPP = 4 weeks
24
Q

How are Taenia spp diagnosed?

Study These Flashcards
A
  • Rarely associated with clinical signs: anal pruritus

- Faecal sample – eggs or proglottids (10g, sampling on 3 consecutive days)

25
How are Taenia spp treated and controlled?
- Praziquantel treatment to remove adult tapeworm (treatment interval dictated by PPP) - Break the life cycle through controlling access to intermediate host/metacestode stage
26
What are the two intermediate hosts of Dipylidium caninum?
Ctenocephalides felis - flea | Trichodectes canis - canine chewing louse
27
Describe the morphology of Dipylidium caninum
- 50cm long - Scolex: 4 unarmed suckers, protrusible rostellum bearing 4-7 rows of small hooks - Many segments, the gravid ones are barrel shaped (rice grains) - Two genital pores on each proglottid - Eggs packaged into capsules, each containing 10-15 eggs
28
Describe the life cycle of Dipylidium caninum
- Adult tapeworm in SI of cat/dog, PPP = 3-4 weeks - Actively motile proglottids are passed in faeces. Disintegrate and eggs released. - Eggs eaten by flea larvae e.g Ctenocephalides felis - Flea larva on floors, carpets, nooks etc - Oncospheres hatch and develop into cysticercoids in body cavity of adult flea - Infected adult flea is eaten as the dog grooms
29
How is Dipylidium caninum treated?
Praziquantel | Flea Control!
30
What spp are the definitive and intermediate hosts of Echinococcus granulosus?
Definitive host: dog | Intermediate hosts: sheep & cattle
31
What is the definitive host of Echinococcus multilocularis?
Fox
32
Echinococcus cause which disease type?
Hydatid disease
33
Describe the hydatid disease of Echinococcus granulosus
- Cystic/hydatid echinococcosis - Outer bladder wall with daughter cysts within - Lots of protoscolices within endogenous cysts
34
Describe the hydatid disease of Echinococcus multilocularis
- Alveolar echinococcosis | - Break off into smaller cysts
35
Describe the morphology of adult Echinococcus
- Very small – 5mm - Only have three proglottids + head - Final proglottid is largest and gravid, shed in faeces - Normally non-pathogenic in the dog
36
Describe the morphology of Echinococcus eggs
- 40 μm - Thick embryophore (outer wall) - Indistinguishable from Taenia eggs
37
Describe the life cycle of Echinococcus
- Metacestode with a hydatid cyst is ingested from the intermediate host - The protoscolices from the cyst emerge and develop into adult worms within the gut - They then produce all of the eggs within the final proglottid which are released into the environment where they infect the intermediate most
38
What is the PPP of Echinococcus granulosus?
6 weeks
39
What is the PPP of Echinococcus multilocularis
4-5 weeks
40
Which Echinococcus spp is not found in the UK?
Echinococcus multilocularis
41
Which spp are the definitive and intermediate hosts of Echinococcus multilocularis?
Definitive host = fox and dog | Intermediate host = small mammals/rodents
42
How are Echinococcus spp diagnosed?
- Rare to see clinical signs except anal pruritis | - Faecal sample – eggs or proglottids: 10g, sampling on 3 consecutive days – as egg release is slower and delayed
43
How are Echinococcus spp treated and controlled?
- Praziquantel treatment to remove adult tapeworm (treatment interval dictated by PPP) - Break the life cycle through controlling access to intermediate host/metacestode stage - Same as hookworms
44
How do human cases of Echinococcosis (E. granulosus) occur?
Infection by ingesting eggs from dogs in contaminated soil, water, food
45
Describe the pathogenesis of human Echinococcosis (E. granulosus)
- Space occupying cyst (hydatid metacestode stage) - Liver, lungs, bone marrow, brain - Slow growing - Asymptomatic incubation period – several years
46
What are the clinical signs of human Echinococcosis (E. granulosus)?
* Clinical signs associated with location of the cyst - hepatic and pulmonary symptoms common. * Jaundice, cholangitis, abdominal pain * Pleurisy (pleural inflammation around the lungs) * Rupture of the cyst – fever, eosinophilia and anaphylactic reaction
47
Describe the pathogenesis of human Echinococcosis (E.multilocularis)
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 lungs and brain - Invade and destroy tissues
48
What are the clinical signs of human Echinococcosis (E.multilocularis)
Pain, Weight loss, Malaise, Liver failure
49
How is human Echinococcosis diagnosed?
* Ultrasonography imaging and CT/MRI scans | * Serology
50
How is human cystic Echinococcosis treated?
Percutaneous treatment of the hydatid cysts with the PAIR (Puncture, Aspiration, Injection, Re-aspiration) technique, drug treatment, surgery
51
How is human alveolar Echinococcosis treated?
Early diagnosis and radical (tumour-like) surgery followed by treatment with albendazole
52
How is human Echinococcosis controlled?
* Controlling disease in definitive and intermediate hosts * Improved hygiene in slaughtering animals * Education programmes
53
What are the 3 specific PET travel scheme requirements relating to tapeworms in dogs?
1. All dogs must be treated with praziquantel 1 – 5 days before ENTRY into the UK 2. A vet must record treatment in the animal’s passport. 3. Repeat treatment again 28 days after returning
Y3 Parasitology S2
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