Neospora caninum

Test code: X0011 - Qualitative detection of Neospora caninum by polymerase chain reaction

Neospora caninum is a recently discovered, apicomplexan, coccidial protozoan that causes abortion in many mammals including cattle, goats, horses and sheep. Some evidence also indicates association of this organism with neonatal neurological and neuromuscular disease in mammals such as dogs, cattle, sheep and deer.

N. caninum-induced bovine abortion has been reported in many countries including the United States, Mexico, Canada, western Europe, Central and South America, Australia and Japan. N. caninum is a major cause of bovine abortion in USA. Prospective and retrospective studies show that 20-45% of bovine abortions in drylot dairies in California were attributable to neosporosis.

In adult cattle infected with this parasite, abortion seems to be the only clinical sign. Bovine fetuses from three months to nine months of gestational age can be infected with this parasite, with most cases occurring between the fifth and seventh month of gestation. Infected calves may be born clinically normal or with neurological signs such as weakness and ataxia.

In infected neonatal dogs, progressive hind limb paresis and paralysis are the most common clinical signs. Skin involvement has only been reported in older dogs. In infected adult horses encephalomyelitis, polyradiculoneuritis and myeloencephalitis can result.

The life cycle of this parasite consists of three stages known as tachyzoite, tissue cyst and oocyst. Tachyzoites are the rapidly multiplying form of the parasite that invades a variety of cells, producing the characteristic lesions of neosporosis in affected animals. The latent form is the tissue cyst, which contains bradyzoites and is found in peripheral and central nervous tissue.

Although other animals may be potential hosts of this parasite, only dogs can serve as both definitive (ie have tachyzoites in their tissues) and intermediate (ie shed oocysts in their feces) hosts of this parasite. When a definitive host ingests tissue cysts from infected intermediate host tissues, sexual development of this parasite takes place. This results in shedding of unsporulated oocysts in the feces. Sporulation occurs outside the host. Intermediate hosts such as cattle, dogs, sheep, goats, horses and deer may then become infected by ingesting food or water contaminated with the oocysts.

Neospora caninum infection is sometimes diagnosed by serology or by specific identification of parasites within tissue lesions using immunohistochemistry (IHC) techniques. However, these methods are not very sensitive and cannot detect some N. caninum infections. Molecular detection by polymerase chain reaction is the most specific, sensitive and rapid method to detect this parasite (Baszler et al., 1999).

Utilities:

• Confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of N. caninum infection
• Ensure that herds and animal populations are free of N. caninum
• Early prevention of spread of this parasite among a herd or population
• Minimize human exposure to this parasite

References:
Baszler, T.V., Gay, L.J., Long, M.T. and Mathison, B.A. (1999) Detection by PCR of Neospora caninum in Fetal Tissues from Spontaneous Bovine Abortions. J. Clin. Microbiol. 37: 4059-4064.

Specimen requirement: 1 ml feces, or 1 ml whole blood in EDTA (purple top) or ACD (yellow top) tube, or 1 ml aborted material, CSF, brain or heart tissue, shipped overnight at room temperature; or frozen tissue shipped frozen.

For specimen types other than those listed here, please call to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative PCR

Normal range: Nondetected