Neospora

Question 1

Which species are affected by Neospora caninum?

Answer 1

Cattle and Dogs

Question 2

How do Neospora diseases differ in cattle and dogs?

Answer 2

Disease in dogs – neonatal paresis

Disease in cattle – abortion

Question 3

What kind of parasite is Neospora caninum?

Answer 3

Apicomplexan protozoa

Question 4

What are the 3 life cycle stages of Neospora caninum?

Answer 4

• Tachyzoite
• Bradyzoite
• Oocyst

Question 5

What is the definitive host of Neospora caninum?

Answer 5

Dogs

Question 6

What is the intermediate host of Neospora?

Answer 6

Dogs

Cattle

Question 7

How does disease transmission of Neospora occur?

Answer 7

Horizontal transmission e.g. dog to cow, dog to dog

Vertical transmission - to offspring

Question 8

Describe the life cycle of Neospora, through both hosts

Answer 8

• Bradyzoites released in dog duodenum
• Unsporulated oocyst passed in dog faeces
• Becomes sporulated in food, water or soil
• Ingested by intermediate host
• Becomes a cyst in the muscle tissue of the intermediate host
• Dog ingests tissue cysts

Question 9

Describe the life cycle of Neospora from a dog to a cow to a foetus

Answer 9

= Exogenous transplacental transmission

• Oocysts excreted in dog faeces, contaminate food and water, ingested by pregnant cows
• Tachyzoites cross the placenta and infect the foetus

Question 10

What are the two outcomes for an infected foetus?

Answer 10

• Abortion

- Persistent infection

Question 11

Describe the life cycle of Neospora from a cow to a foetus, without the definitive host

Answer 11

• Endogenous transplacental transmission
• Persistently infected cow – recrudescence of infection
• Slow growing bradyzoites persist within the tissue cysts in neural tissue
• Cow doesn’t show any clinical signs
• During pregnancy bradyzoites differentiate into rapidly dividing tachyzoites – thought to be due to a drop in the cows immunity during pregnancy

Question 12

What are the consequences for the calf if infected in each of the 3 pregnancy trimesters?

Answer 12

1 - early embryonic death
2- foetal death, abortion, born with congenital defects
3 - weak, brain damaged or normal

Question 13

How can abortion due to Neospora caninum be diagnosed?

Answer 13

Maternal serology - ELISA - test for antibodies in the second half a pregnancy
Foetus - antibody detection in foetal fluids
Foetal histology of brain or heart

Question 14

How can endogenous transmission of Neospora be controlled?

Answer 14

• Identification of positive cows: serology of the whole herd
• Cull infected cows
• Embryo transfer, insuring recipients are negative

Question 15

How can exogenous transmission of Neospora be controlled?

Answer 15

• reduce the risk of infection of dogs
• dispose of afterbirth and aborted material
• minimise risk of contamination of cattle feed with dog faeces
• no current drug development or vaccine