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Information on Diseases

Crichton dairy cow and calf
Pictured: PhD student Aluna Chawala meeting with a dairy farmer.

Neospora

What is Neospora?

Neospora caninum is a parasite that infects cattle and can cause abortion.  Cattle can become infected in two ways:

  • By eating Neospora oocysts (eggs) from the environment along with food or water
  • As an unborn calf when Neospora crosses the placenta from an infected cow

Infection can arrive on farm by several routes:

  • Via purchase of an infected cow
  • Via recently infected dogs
  • In feed or water contaminated by dog faeces

Dogs are a vital part of the Neospora story.  They become infected by eating Neospora infected placentae, foetuses, calves or wildlife.  The parasite multiplies in their intestine and oocysts are passed in faeces for two to three weeks.  After this the dog is immune and no longer a risk.  As oocysts are only shed when the dog is infected for the first time this is most likely to occur in pups or young dogs.  The oocysts are thought to survive in the environment for many months.  After being eaten by a cow the oocysts multiply and then become dormant within tissue cysts.  This has no ill effects on the cow which continues to appear healthy.  The danger comes during pregnancy when the parasite re-activates and travels to the placenta and unborn calf.  What happens next can include:

  • Abortion – abortion storms can occur when infection is introduced to a herd for the first time
  • The birth of a healthy, but infected, calf which may go on to abort during its first pregnancy
  • The birth of a calf showing signs of nervous disease, however, this is uncommon

Infected cows remain infected for life and maintain Neospora in the herd by giving birth to infected heifer replacements.  There is no evidence of direct cow to cow spread.

How can PCHS members become accredited for Neospora?

Within CHeCS, the Neospora programme is moving to risk-level certification (similar to the Johne’s programme).   This change has been made in light of reviewing the latest research and to make the programme achievable for all herds to participate. Herds will be assigned a risk level, from 1 to 5 as below, with 1 being associated with the lowest risk of being a source of Neospora infected stock.

Level 1:  Three or more consecutive clear annual herd screens.

Level 2:  One or two consecutive clear annual herd screens.

Level 3:  The number of test positive animals does not exceed 5% of the herd eligible for testing in the Neospora programme.

Level 4:  More than 5% of eligible animals identified as test positive animals at the most recent test.

Level 5:  These herds may be carrying out a testing programme, but are not adhering to the mandatory requirements of the programme.

All breeding females over one year of age must be tested annually. Testing can be carried out on the same day or at intervals throughout the year to fit in with management purposes. The programme has mandatory control elements to ensure that infected females are not retained in the herd for breeding. A health plan must be in place to ensure that farm dogs cannot acquire or pass on infection to cattle. Abortions must be investigated. Herds can choose how quickly they wish to progress through the risk levels. It is possible for example to retain high genetic merit test-positive cows to breed bulls. If doing this however, the herd cannot progress above level 3 until the test positive animals are removed. For further information contact the PCHS team.

 

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