Neosporosis: a Major Cause of Reproductive Failure in Cattle

Moredun-logoSummary written by Elisabeth A Innes BSc (Hons) PhD and Frank Katzer BSc (Hons) DPhil

Taken from Moredun Foundation Newsheet Volume 5 No. 10 (2011)



  • angus cattle copyright Fran-RogersNeosporosis is an important, infectious disease of cattle world-wide that results in abortion and stillbirth. Economic losses associated with bovine neosporosis include: abortion, premature culling and reduced milk yields.
  • Neosporosis is caused by Neospora caninum, a single-celled organism (a protozoan parasite).
  • Neosporaeggs (oocysts) are produced by infected dogs and excreted in their faeces. Cattle become infected if they eat food or drink water contaminated with Neospora oocysts.
  • Infection in cattle is common and may frequently be passed from mother to calf during pregnancy, often over successive generations. The parasite has evolved this important mechanism to aid its survival.
  • Disease occurs when Neospora multiplies in the cells of the developing calf and its placenta and causes sufficient damage to trigger abortion or stillbirth.
  • The timing of infection during pregnancy is critical to the disease outcome: the earlier in gestation that the parasite infects the placenta and foetus the more severe the consequences.
  • Moredun has recently developed a new rapid diagnostic test for neosporosis based on detection of tiny quantities of specific genetic material from the parasite.
  • Control of neospora abortion is difficult but certain management rules and biosecurity measures can be applied to reduce the risks. Pharmaceutical preparations are known that will kill Neospora in laboratory conditions, but their use to control infection/disease in cattle is either impracticable or not effective.
  • There is accumulating evidence that cattle having experienced abortion due to Neospora are less likely to abort again due to the same infectious agent.
  • No vaccine is currently licensed for preventing neosporosis in cattle in the UK. Although a vaccine, Bovilis Neoguard® is available in the USA and some other countries worldwide.
  • Current knowledge suggests that Neospora does not cause disease in human beings.


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