Canis ISSN: 2398-2942

Neospora caninum

Synonym(s): N. caninum

Contributor(s): Kyle Braund, J Dubey, SandyTrees

Introduction

Classification

Taxonomy

  • Phylum: Apicomplexa
  • Class: Sporozoea
  • Subclass: Coccidia
  • Genus: Neospora.

Active Forms

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Resting Forms

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Clinical Effects

Epidemiology

Habitat

  • Identified in tissues of dogs, cattle, goats, sheep, horses and deer; experimentally in cats, monkeys, rodents.
  • Inhabit many cells, eg macrophages, fibroblasts, endothelial cells, myocytes, renal tubular epithelial cells, hepatocytes and neural cells.
  • Cysts in brain, spinal cord, nerves and retina.

Lifecycle

  • Unknown. Recently recognized as distinct from Toxoplasma (1988).

Transmission

  • Transplacental. Frequency of vertical transmission of naturally acquiredN. caninumis variable, but too low to sustain infection alone. Post-natal infection must occur to maintain infection.
  • In cattle - vertical transmission to calves - via placenta and colostrum is probable.
  • Horizontal transmission, via infected dog feces may also be involved although fecal shedding of oocysts is low except in immunosuppressed dogs.
  • Experimentally; orally, parenteral injection.
  • Excretion of oocysts by carnivorous definitive hosts is suspected stage in lifecycle.
  • Higher prevalence ofN. caninumin farm and breeder dogs, as compared with urban dogs, suggests that horizontal transmission ofN. caninumfrom cattle to dogs and from dog to dog may occur.

Pathological effects

  • Inflammation develops around groups of actively multiplying tachyzoites.
  • Intracellular cysts do not provoke host reaction.
  • Cell destruction caused by multiplication of tachyzoites → necrotic lesions.
  • Infiltrate associated with cell destruction includes mononuclear cells, neutrophils and eosinophils.
  • Destruction of large neural cells, eg those in brain/spinal cord can occur.

Other Host Effects

  • Parasites invade cells.
  • Subclinical infection common.
  • Major cause of abortion storms in cattle in Australia and New Zealand.

Control

Control via animal

  • No clinical trials have been undertaken.

Control via chemotherapies

  • No drug licensed for use against N. caninum.
  • Some animals respond to chemotherapy in the early stages of limb weakness.
  • Trimethoprim Trimethoprim /sulfadiazine Trimethoprim : 15 mg/kg BID for 4 weeks (occasionally → gastroenteritis).
  • Pyrimethamine Pyrimethamine : 1 mg/kg/day for 4 weeks.
  • Clindamycin Clindamycin : 20 mg/kg BID for 3-4 weeks (occasionally → gastroenterirtis). Pyogranulomatous dermatitis may be treated over 45 days at 7.5 mg/kg TID.
  • Combination of above drugs.
  • Early treatment more likely to be successful.

Control via environment

  • Prevent access of dogs to expelled placentas, fetuses and possibly raw beef.
  • Selective culling of affected animals.
  • Do not breed from infected animals.
  • No specific control measures.

Other countermeasures

  • Treatment of infected bitches does not prevent subsequent transmission to young.

Diagnosis

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Further Reading

Publications

Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Lorenzo V, Pumarola M & Siso S (2002) Neosporosis with cerebellar involvement in an adult dog. JSAP 43(2), 76-79.
  • Boydell P & Brogan N (2000) Horner's syndrome associated with Neospora infection. JSAP 41, 571-572.
  • Reichel M P (2000) Neospora caninum infections in Australia and New Zealand. Aust Vet J 78, 258-261.
  • Lindsay D S et al (1999) Confirmation that the dog is a definitive host for neospora caninum. Vet Parasitol 82(4), 327-333.
  • Barber J S & Trees A J (1998) Naturally occurring vertical transmission of neospora caninum in the dog. Int J Parasitol 28(1), 57-64.
  • Pearl S et al (1998) Cutaneous neosporosis in a dog in Israel. Vet Parasitol 79(3), 257-261.
  • Barber J S & Trees A J (1996) Clinical aspects of 27 cases of neosporosis in dogs. Vet Rec 139, 439-443. (Diagnosis and treatment of neosporosis.)
  • Barber J S, Payne Johnson C E & Trees A J (1996) Distribution of Neospora caninum in the central nervous system and other tissues of 6 dogs with clinical neosporosis. JSAP 37, 568-574. (Histological recognition.)
  • Dubey J P & Lindsay J S (1996) A review of Neospora caninum and neosporosis. Vet Parasitol 67, 1-59. (A review by the world's expert.)

ADDED