Quiz 4 Flashcards
What type of lifecycle do ALL cestodes have
Indirect
Where do adult cestodes inhabit in definitive host
GI tract
Where do larval cestodes inhabit in intermediate host
Extraintestinally
What is a larval cestode called
Metacestode
What is the gravid part of the cestode called
Proglottid
Where are nutrients absorbed in cestodes
Skin
What is the anterior part of the cestode called
Scolex
What type of tissue makes up the neck of the cestode
Undifferentiated tissue
What are the chain segments of cestodes called?
Strobila
T/F - Proglottids contain male and female genitalia
True! They are hermpaphrodites
Are proglottids more mature anteriorly or posteriorly
Posteriorly - they mature as they move away from the neck region
What are cestode eggs called
Oncospheres
What’s this

Hydatid cyst
What’s this

Coenurus
What’s this

Strobilocercus
What’s this

Cysticercus
What’s this

Tetrathyridium
What’s this?

Plerocercoid
What’s this

Procercoid
What’s this?

Oncosphere
How many suckers do Taenia have?
4 suckers
What do some Taenia suckers have?
Non-retractile rostellum – with 2 concentric rows of hooks
What are these

Taenia eggs
- Spherical*
- Thick-walled*
Definitive host of most Taenia
Canids, humans
Where are gravid segments shed?
Shed in intestine of definitive host
Proglottids in feces
How are Taenia eggs released
They are shed inside proglottis. They are then either
a) while the proglotid crawls on host’s fur
b) while proglottid is on fecal surface
Where are metacestodes typically found
In the liver, peritoneal membrane, or cardiac/skeletal muscle of intermediate host
Intermediate host forms fibrous tissue capsule around the metacestode
What is the most common Taenia tapeworm of dogs in the US?
T. pisiformis
What is the intermediate host of Taenia pisiformis? Where are metacestodes found?
Rabbits, hares.
Metacestodes (Cysticercus pisiformis) in liver, peritoneum
Describe metacestode of T. pisiformis
Cysticercus
Single fluid filled sac with one invaginated scolex

You see an eviscerated rabbit while walking in the woods. What do you suspect is growing on its intestines?

Cysticercus pisiformis
Cysticerci of Taeniae pisiformis
Fluid filled sac with an inverted scolex
What is the intermediate host of Taenia ovis? Where do metacestodes develop
Sheep
Metacestodes develop in skeletal and cardiac muscles
You’re at a slaughter house and they notice cysticerus in a sheep’s quadricep muscle. Are you concerned? What do you suspect?
This is probably Cysticercus ovis (Taenia ovis). Yes you are concerned —> lesions willcondemn sheep at slaughter
This is a sheep’s heart. What is wrong with it?

Cysticercus ovis growing in cardiac muscle
What is known as a ‘thin necked bladder worm’
Taenia hydatigena
What’s this

Taenia hydatigena
What’s this

Taenia hydatigena
What is the intermediate host of Taenia hydatigena? Where does the metacestode live?
Ruminants and swine
Metacestode migrates through lvier and encysts in peritoneum
- *Hepatitis cysticercosa**
- *Black Disease**
The fox is a definitive host of which Taenia spp.?
Taenia ovis
The cat is a definitive host of which Taenia spp?
- T. taeniaeformis *most common*
- Taenia hydatigena (wild felids)*
Humans are the definitive host of which Taenia spp.?
- T. saginata*
- T. solium*
Dogs are the definitive hosts of which Taenia spp?
- T. pisiforms *most common
- T. ovis
- T. hydatigena
- T. multiceps
What is the definitive host of T. hydatigena
Canids and wild felids
What is the metacestode stage of Taenia hydatigena called?
Cysticercus tenuicolis
What does Cysticercus tenuicolis cause? In who?
Causes hepatitis cysticercosa and black disease in intermediate host (ruminants and swine)
Your client is a pig farmer and sends you a photo of the liver of a sow he just slaughtered. What do you suspect is causing this?

Hepatitis caused by Cysticercus tenuicolis
What is ‘Black Disease’ and what causes it
Green nodules on surface of liver caused by Cysticerucs tenuicolis + Clostridium noyvi
Which Taenia spp has a metacestode that switches from Cysticercus to Strobilocercus
Taenia taeniaeformis
What is the definitive host of Taenia taeniaeformis
Cats
What is the intermediate host of Taenia taeniaeformis and where does it live
Mice and rodents
Lives in liver
What does this?

Taenia taeniformis
What is this

Coenurus cerebralis (the metacestode of Taeni multiceps)
What is the metacestode of Taenia multiceps called? What does it look like
Coenurus cerebralis
It is large, fluid filled with clusters of scolices in internal wall

What is definitive host of Taenia multiceps
Dogs and Wild Canids
What is host of Coenurus cerebralis? Where does it live?
Sheep and goats, Cows
Rarely in cats —> fatal
Lives in cranial cavity and spinal cord
What is ‘True Gid’ caused by
Coenurus cerebralis
Neurologic signs due to progessive SOL (blindness, incoordination)
What are two differentials for True Gid
Bacterial encephalitis
Rabies
(caused by Coenurus cerebralis)
Which Taenia spp are zoonotic and reportable?
- T. saginata*
- T. solium*
How can you tell the difference between T. solium and T. saginata
T. saginata doesnt have rostellum or hooks
Which reportable Taenia spp has cattle as intermediate host? Where does it live in cattle?
T saginata
Found in striate muscle - viable for 9+ months
How are humans infected with T. saginata? What are the c/s?
Ingesting cysts from raw/undercooked beef
C/S
- Diarrhea
- Hunger pains
- Usually asymptomatic
Which reportable Taenia spp has pigs as intermediate host? Where does it live in pigs?
T. solium
Lives in striated muscle
What’s this?

Taenia solium
(Identifiable feature: rostellum, 2 rows of hooks)
What’s the accidental intermediate host of Taenia solium?
Humans —> BAD NEWS!
Causes cysticerocis – nervous, ocular, pulmonary
A human consumes a T. solium cysticerci in raw pork. Should that person be concerned
No - humans are the definitive host of Taenia solium and consuming the cysticerci will cause no symptoms
A human consumes raw pork which was found to contain T. solium eggs. Should that person be concerned?
YES - humans can the an accidental intermediate host.
Can cause cysticercosis - nervous, ocular, pulmonary disease
Also can affect human muscle –> requires surgical removal
What would cause this?

Cysticercus cellulosae
Taenia solium cystercerci - very dangerous
Your client is a swine farmer and has been complaining about muscular and occular pain. You notice his eye looks strange. What’s a worrying differential?

Cysticerucs cellulosae
(Taenia solium cystercerci)
Name 3 ways you can diagnose Taenia solium in humans
CAT scan
MRI
X-ray
What is this?

Echinococcus
Definitive host of Echinococcus
Domestic and wild dogs
Intermediate host of Echinococcus
Everything else - incl humans
What can cause a hydatid infection in humans?
Echinococcus
What is a hydatid infection
Cysts forming that contain tapeworm larvae (Echinococcus)
A cat has a hydatid infection. Is surgery the best treatment option
NO - you need to PAIR
Puncture
Aspirate
Insert solution
Re-aspiration
Intermediate host of Echinococcus granulosus
Ruminants
Horses
Pigs
Camelids
Humans
How are intermediate hosts infected with Echinococcus granulosus
Ingesting eggs (fecal-oral)
Definitive host of Echinococcus granulosus? How are they infected and what are c/s?
- Dogs and wild dogs
- Infected by ingesting cysts from organs of IH
- Asymptomatic
What is cystic hydatid disease?
Disease caused by ingesting Echinococcus granulosus eggs
- Unilocular
- Liver, lungs
- Humans: respiratory signs, abdominal distension
- Allergic reaction to hydatid fluid leaks = death (anaphylaxis)
What causes this

Echinococcus granulosus
You have a pygmy goat come in with an Echinococcus granulosus cyst on its liver. What would you do to treat it?
Aspirate it taking care not to let fluid leak –> anaphylactic shock!
T/F Echinococcus granulosus is asymptomatic in most animals
True - symptoms usually stem from pressure atrophy on surrounding organs
T/F - Echinococcus granulosus cysts invade organs
False
Definitive host of Echinococcus multilocularis
Dogs, cats, wild canids
How are dogs infected with Echinococcus multilocularis? What are c/s?
Ingest cysts from ogans of IH - asymptomatic
Intermediate host of Echinococcus multilocularis? How are they infected
- Small rodents
- Cows
- Horses
- Swine
- Humans!
Infected by eating eggs
What causes alveolar hydatid disease? What is it?
Echinococcus multilocularis
Multilocular disease in liver - usually fatal!
Your PM’ing a cow and the liver looks like this. What do you suspect?

Alveolar hydatid disease caused by cysts of Echinococcus multilocularis
Which Echinococcus spp infiltrates tissues
E. multilocularis
Which Echinococcus spp forms brood capsules
E. multilocularis
Which Echinococcus sp causes respiratory signs and abdominal distension in humans?
Echinococcus granulosa
Which Echinococcus sp is unilocular
Echinococcus granulosa
You are PM’ing a rat and see these infiltrative masses. What do you suspect?

Echinococcus multilocularis
T/F - you can differentiate Echinococcus eggs from Taenia eggs as they are morphologically very distinct
False - they look identical
What forms a unilocular hydatid cyst
Echinococcus granulosum
What forms an alveolar hydatid cyst
Echinococcus multilocularis
Which cestode species forms egg packets
Dipylidium caninum

What’s this

Dipylidium caninum eggs
What’s this

Diplydium caninum
What is the intermediate host of Dipylidiums caninum? What must definitive host eat to get infected
Intermediate host = fleas
- Definitiive host must eat the flea
What’s this

Dipylidium caninum
What is the metacestode of Taenia saginata called
Cysticercus bovis
T/F - Dipylidium canis is pathogenic in definitive host? What is a C/S?
False, but may cause ‘pruitus ani’ - scooting (due to discomfort)
How do you educate owners on D canis prevention?
Flea control
An owner found these on her dog’s butt. What are they?

Dipylidium caninum
What is the metacestode of Taenia ovis called
Cysticercus ovis
What is the metacestode of Taenia pisiformis called?
Cysticercus pisiformis
What is the metacestode of Taenia taeniformis called
Strobilocercus or Cysticercus fasciolaris
(changes formation 45 days in)
What is the metacestode of Taenia solium called
Cysticercus cellulosae
A butcher calls to ask about a parasite he has found the in the abdominal muscles of a cow. What do you suspect?

Cysticercus bovis
(from Taenia saginata)
Metacestode of Dipylidium caninum
Cysticercoid caninum
Main diagnostic stage of Taenia
Proglottids and eggs in feces