Neospora

Question 1

What species does Neospora caninum affect?

Answer 1

Cattle and Dogs

Question 2

What does neospora disease caninum cause in different animals?

Answer 2

Dogs- naonatal paresis

Cattle- abortion

Natural infections in dogs, cattle some sheep, goats, horse and deer

Question 3

What are the life cycle stages of neospora?

Answer 3

Tachyzoite- rapidly dividing, intracellular- preference for monocyte/macrophage but will invade any

Bradyzoite- slowly replicating, forms intracellular cyst, preference for neurological tissues including brain and spinal cord

Tachyzoite differentiated into bradyzoite but can differentiate back into tachyzoite again

Oocysts- result of sexual reproduction, only found int eh faeces of definitive host (dog, wolves, dingoes)

Question 4

What kind of hosts are dogs and cattle of neospora?

Answer 4

Dogs are definitive host but can also be intermediate

Cattle are intermediate host

Question 5

Describe the lifecycle of neospora with a cow and dog

Answer 5

Dogs scavenge infected bovine tissues and ingest bradyzoites

Enteric sexual cycle, syngamy with macro and microgamtetes to form a zygote, excretes as an oocyst

Oocysts sporulate and excreted in dog faeces, contaminate food and water and ingested by cattle

Question 6

Describe the life cycle of neospora with a dog, cattle and a foetus

Answer 6

Exogenous transplacental transmission

Pregnant cows ingest oocysts contaminated food or water

Parasite becomes tachyzoite and infects dam

Tachyzoites cross the placenta and infect the foetus

Leads to either abortion or leads to persistently infected calf

Question 7

Describe the life cycle of neospora with a cow and a foetus

Answer 7

Recrudescence of a persistent infection: endogenous transplacental transmission

Slow growing bradyzoites persist within tissue cysts in neural tissue

During pregnancy bradyzoites differentiate into rapidly dividing tachyzoites

A persistenlty infected cow wither aborts or produces a persistently infected calf

Question 8

What percentage of calves born to neospora infected mothers are born infected themselves?

Answer 8

95%

Question 9

What happens if a pregnant cow is infected with oocysts of neospora?

Answer 9

Exogenous transplacental transmission leading to either abortion and a persistently infected calf

Question 10

What are the two patterns of neospora-associated abortion?

Answer 10

Endemic abortion pattern- annual abortion rate >3%

Epidemic abortion pattern- abortion storm- >10% of at risk cows abort over a 12 week period

Question 11

What is endemic and epidemic neospora associated abortion associated with?

Answer 11

Endemic- endogenous transplacental transmission, very efficient and common route of transmission

Epidemic- exogenous transplacental transmission- ingestion of oocysts during pregnancy

Question 12

How can neospora be diagnosed in a cow?

Answer 12

Maternal serology- ELISA

Antibody levels fluctuate during repro cycle

Testing of cows 2nd half of pregnancy

Eliminate other casues

Question 13

How can neospora be diagnosed in a foetus?

Answer 13

Antibody detection in foetal fluids

Histology- brain/heart, non-supprative encephalitis

Immunohistology

Question 14

How is neospora controlled?

Answer 14

Not easy

No current drugs

No vaccine currently availible

Managment stratagies

Question 15

How is endogenous transmission of neospora controlled?

Answer 15

Identify positive cows- serology of whole herd, test calves at birth

Cull infected cows- Expensive, Depends on the number infected

Selective breeding to beef- no cow to cow transmission, no zoonotic risk

Embryo transfer- ensure recipients are negative

Question 16

How is exogenous transmission of neospora controled?

Answer 16

Reduce risk of infection of dogs- dispose of afterbirth or aborted material carefully

Minimise the risk of contamination of cattle deed with dog faeces

Biosecurity