Tapeworms of Ruminants Flashcards
What are some generic features of cestodes/tapeworms?
Adult worms are segmented
Indirect life cycles
Adult parasite in difinitive host, generally considered less pathogenic
Stage in the intermediate host is referred to as the metacestode, can be considered pathogenic
Describe the outside structure of an adult tapeworm?
Scolex at top of head- sometimes with suckers- and attaches to host
Extends into a neck and then segments
Newly produced segments- proglotids- near head
All the segments together form the Strobila
Describe the inside strucutre of an adult tapeworm’s proglottid
Testes lined up around the outside
Dark structure at bottom of segment- vitelline gland- produces egg shell
Viteline gland connected to ovary and uterus which extends through middle
Connected to genital pore
How do tapeworms ingest food?
The tegument- body wall- allows passage of food
No gut
What is the order and families of the relevant tapeworms?
Order: Cyclophillidae
Families:
Taeniidae
Dilepididae
Anoplocephalidae
Describe the general life cycle of a tapeworm
Adult tapeworm always found in difinitive host, metacestode found in intermediate host
Adults found in SI
Proglottids break off
Eggs/proglottids shed in faeces
Eggs immediatley infective
Eggs eaten by intermediate host
Metacestode develops in intermediate host
Metacestode eaten by difinitive host
What are the 4 different types of metacestode?
Cysticercus
Coenurus
Hyatid
Cysticercoid
What kind of metacestode is this and why?
Cysticercus- one single invaginated scolex
What type of metacestode is this and why?
Coenurus- several invaginated scolex
What type of metacestode is this and why?
Hyatid- endogenous and exogenous cysts containing several scolex
What type of metacestode is this and why?
Cysticercoid- exvaginated scolex, not fluid filled- solid structure
Very small
What are the 4 tapeworms which are metacestodes in sheep and dogs are the definitive host?
Taenia ovis
T.hydatigena
T.multiceps
Echinococcus granulosus
Where are the metacestode of taenia ocivs found in sheep?
Cysticercus in muscles
Where is the metacestode of Taenai hydatigena found in sheep?
Cysticercus in peritoneum
Where are the metacestode of taenia multiceps found in sheep?
Coenurus in brain
Where is the metacestode of echinococcus granulosus found in sheep?
Hydatid cyst in liver or lung
What parasite causes sheep measles?
Taenia ovis- cysticercus in muscles
What is the problem and solution for ‘sheep measles’?
Affects value of carcase
Major economic losses in Australia and New Zealand
Vaccine produced- recombinant oncosphere antigen. Highly effective, no commercial take up
New Zealand- education and regular worming of dogs
Canada- Liver condemnations have increased a lot
What is the problem of Taenia hydatigena in sheep?
Cysticercus migrates through the sheep
Forms mature cysticercus in the peritoneum
Liver condemnation
What are the complications of taenia multiceps and why?
Neurological complications
Space occupying lesion from cyst in the brain of the sheep- (coenrus)
What is the problem with Echinocococcus granulosus
Hyatid cyst in liver and lungs- no pathogenic significance for sheep and cattle
Serious Human pathogen
How can tapeworms (metacestode) of sheep be controled?
Praziquantel treatment of dogs to remove adult tapeworm (dictated by PPP, every 6 weeks)
Break the life cycle through controlling access to intermediate host/metacestode stage
Can’t treat metacestode
What tapeworms have humans as their definitive host?
Taenia saginata- beef tapeworm
Taenia solium- pork tapeworm
How does taenia saginata affect the UK?
Rare
Adult in SI of humans
Metacestode in muscle of cattle- cysticercus
No disease in cattle
Mild disease in humans- hunger pains, aesthetically unpleasant
How are tapeworms (taenia saginata) in humans controlled?
Meat inspection- heart, masseter muscles- heavy infestation leads tos carcase condemnation
Cooking or freezing meat
Sewage disposal
How does Taenia solium affect the UK?
Not in the UK (eradicated)
Where are the different stages of Taenia solium?
Adult tapeworms in humans- non pathogenic
Metacestode in pigs AND humans
Cysticercus in mucle of pigs
Highly pathogenic cysticercosis and neurocysticercosis in humans
What causes human cysticercosis from taenia solium and what does it cause?
Ingestion of eggs associated with poor sanitation
Ingestion of metacestode
Presence of cysticerci in pigs/lack of meat inspection
Human disease- epilepsy, head aches, sub-cutaneous lumps, neuro and ocular cysticercosis
What adult tapeworms are found in sheep and cattle?
Monezia spp
Where is Monezia spp found in cattle and sheep?
SI of sheep- long 2m+
What is the metacestode stage of Monezia spp?
Cysticerdoid develops in oribatid mite
What is the name of the metastronglye lung worm found in sheep?
Muellerius capillaris
Where are meullerius capillaris found in sheep and how are they infected?
Found in the lung parenchyma- eosinophilic nodules, grey/green
L1 in faces
Intemediate hosts are slugs and snails
Not pathogenic in sheep- highly pathogenic in goats
What area bunch of fluid filled cysts in the peritoneum associated with the liver of the sheep at an abattoir likely to be?
Taenia hydatigena
During meat inspection you find a 1 cm cyst in the (a) leg of a sheep, (b) the masseter of a cow, (c) lungs of a lamb. What are they likely to be?
(a) Taenia ovis
(b) Taenia saginata
(c) Echinococcus granulosus
Name three Zoonotic parasites of sheep anc cattle that you can detect at the abbatoir and which stage is found?
Echinococcus granulosis- metacestode in sheep and cattle
Taenia saginata- cysticercus in muscle
Fasciola hepatica- immature and mature fluke in liver/bile ducts
How are sheep infected with T. hydatigena and T. ovis?
Through ingesting eggs shed in dog faeces (dogs are definitive host, harbour the adult tapeworm, mestacodes found in sheep)
What is this?
Monezia spp egg- world cup trophy
Adult tapeworms in gut of sheep
What is this?
Taenia spp or echinococcus eggs found in faces of dogs
How would you differentiate between L1 larvae of meulleris capillaris and dictyocaulus filaria in faeces of a sheep?
D. filaria has a circular knob on the anterior end
M.capilaris has a spike on the tail
How are sheep infected with D.filaria and M.capillaris?
D.filaria has a direct life cylcle, infection via L3 that develops on pasture
M.capillaris has an indirect life cycle with a mollusc intermediate host, infectoin via L3 in snail/slug
Mc not pathogenic
