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Flashcards in SA Protozoa Deck (19):

Describe Neospora caninum

An apicomplexan protozoan similar to T. gondii


Neonatal paresis and abortion in cattle is characteristic of which parasite?

Neospora caninum


Outline the lifecycle of Neospora caninum.

  1. Dogs scavenge infected bovine tissues and ingest bradyzoite cysts
  2. Enteric sexual cycle
  3. Oocysts excreted in dog faeces. Contaminate cattle food and water.
  4. Asexual reproduction of tachy and bradyzoites
  5. Tachyzoites in cattle cross the placenta and infect the foetus

A image thumb

How do number of oocysts excreted by the definitive host differ between Neospora and Toxoplasma?

Toxo ++++

Neospora - only up to 500k


The dog can act as an intermediate and definitive host of N. caninum. How does this work?

Which method of transmission of N. caninum results in neonatal paresis?

How do these dogs serology compare?

  1. Host types
    1. Definitive host: ingestion of bradyzoite cysts from bovine tissues
    2. Intermediate host: transplacental transmission
  2. Transplacental transmission
  3. Definitive hosts are not Ab positive whereas intermeds are. Also intermeds do not have oocysts in their faeces.


What clinical signs are associated with N. caninum in puppies?

  • Ataxia
  • Hindlimb paresis
  • Loss of reflexes
  • Ascending paralysis
  • Dysphagia
  • Hyperextension of hindlimbs


What clinical signs are associated with N. caninum in older dogs?


  • CNS disturbances
  • abnormal behaviour
  • vision defects
  • seizures
  • myocarditis
  • dermatitis
  • pancreatitis


Describe diagnostic techniques which can be used for N. caninum

Clinical signs - see prev slide

Serology - intermediate vs definitive hosts

CK elevation - muscle damage

Muscle biopsy - PCR or immunocytochemistry of parasites


How is N. caninum treated in dogs and cattle?

  1. No current approved treatment in Cattle
  2. Dogs: prolonged clindamycin/ potentiated sulphonamides 

Remember: Prognosis is variable


Name two other minor protozoal species in dogs and describe their clinical signs.

  1. Isospora - diarrhoea in puppies and kittens
  2. Sarcocystis - abortion and meat condemnation in cattle and sheep 


Traveller's diarrhoea in humans can be caused by which protozoal species?



Describe the morphology of Giardia trophozoites and cysts.

  1. T - Binucleated, tear drop shaped, 8 flagella, adhesive disc
  2. C - Oval/ ellipsoid, 8x12um, 2-4 nucleii

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Which Giardia spp. is most relevant in the domestic species?

What is conveyed by the spp. strain assemblages? Which assemblages are associated with multi-host infection?

Giardia duodenalis

Assemblages of G. duodenalis convey species specific infectivity.

  • A - Human, livestock, dog, cat
  • B - Human, dog, rat


Outline the lifecycle of Giardia.

  1. Infective cysts are ingested by the host
  2. Encyst in the small intestine and develop to trophozoites
  3. Trophozoites multiply asexually by binary fission (longitudinal)
  4. Fate
    1. Single trophozoites excreted disintegrate
    2. Multinucleated resistant cysts excreted in the faeces

A image thumb

What clinical signs are associated with Giardia infection?

How can infection be diagnosed?

  • Trophozoites erode mucosa and villi
  • Malabsorptive diarrhoea
  • Steatorrhoea (greasy stools)

Diagnosis is via identification of trophozoites and cysts in stools.


Name two ways in which Giardia can be transmitted.

  • Faecal-oral ingestion of cysts
  • Asymptomatic carriers


What control measures can be put in place to reduce risk of Giardia infection?

Outline the treatment of Giardia in dogs.

  1. Good hygiene, poo picking, clean drinking water
  2. Treatment with metronidazole, FBZ is liscenced in puppies


Tritrichomonas foetus is associated with what clinical signs in cats and cows?

How can it be treated/ diagnosed?

Cows - abortion and infertility (eradicated in the UK)

Cats - diarrhoea/ colitis

Tx. Metronidazole/ FBZ



What are the morphological features of Tritrichimonas foetus?

  • 5-25 µm
  • Spindle shaped
  • Four flagella - three of which are motile
  • Undulating or wavy membrane