Neospora

• 2 main species
  • Neospora caninum in the dog
  • Neospora hughesi in the horse

• Sporulated oocysts measuring just 10μm

• Oocyst contains 2 sporocysts with 4 sporozoites

• Route of transmission not fully understood

• Often misdiagnosed as Toxoplasma gondii
  • Sarcocystis cysts have thicker walls

• Infection diagnosed by IFAT, ELISA or PCR
  • Identification of lesions and organisms in tissue using immunohistochemical staining
  • Eliminate other causes of abortion first

Life cycle

• Life cycle similar to Toxoplasma gondii

• Limited range of warm-blooded intermediate hosts
  • Asexual reproduction occurs in intermediate host forming tissue cysts

• Host range of sexual stage is unknown for N.caninum
  • Intermediate host for N.hughesi is the horse, but the definitive host is unknown

• Final host
  • Dogs pass oocysts
  • Role not fully understood in pathogenesis
  • 5 day prepatent period
  • Other wild canids may also act as final definitive hosts

• Intermediate host
  • Mostly cattle
  • Natural infection has been documented in other herbivores

• Transmission
  • Transplacental infection occurs in all intermediate hosts and in the canine final host
    • Transplacental transmission can occur in successive pregnancies
  • In cattle, vertical transmission occurs
    • Post-natal infection occurs but is less common

• Neospora caninum in myositis

Pathogenesis

Dog Neosporosis

Cattle Neosporosis

Horse Neosporosis

• N. caninum
  • Necrotising inflammation of muscles
  • Myositis more severe than in toxoplasmosis

N. caninum - A disease of cattle with late abortion of mummified or autolysed foetus. May also get foetal malformation, e.g. arthrogryposis.

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