Neospora hughesi (EPM)

Test code: X0009

Test name: Ultrasensitive qualitative detection of Neospora hughesi by real time polymerase chain reaction

Equine Protozoal Myeloencephalitis (EPM) is one of the most challenging and exasperating diseases in horses, not only for veterinary scientists but for horse owners as well. EPM is the most commonly diagnosed neurologic disease of horses in North America (MacKay, 1997). It occurs when protozoal parasites infect and invade the central nervous system. EPM infection results in characteristic lesions in the brain and spinal cord that are evident during necropsy. The presence of these lesions correlates well with the clinical signs generally attributed to EPM (ataxia, muscle atrophy, etc).

Until the availability of molecular testing, it was almost impossible to definitively identify the causative agent and infection status of an affected horse. If a horse showed signs of neurologic problems, the veterinarian began a process of elimination to determine what was NOT causing the symptoms. Traditional EPM tests were only effective at determining that the horse did not have EPM. If traditional EPM test results were positive, that only definitively revealed that the horse had been exposed in the past to the parasites that cause EPM. Testing could not show whether the horse had an active infection by those parasites.

Until recently the parasitic organism Sarcocystis neurona was thought to be the sole cause of EPM. However, a newly identified parasite, Neospora hughesi, has now been recognized as another cause of this disease. Both species are challenging to treat due to the concealment of cysts in tissue, which can result in recrudescence of infection even after treatment. Because infections from N. hughesi, their lesions and the actual parasites are so similar to S. neurona, it is likely that some Neospora infections have been mistaken in the past for Sarcocystis infections.

PCR is the most specific and sensitive method available for detection of Neospora hughesi. This testing technique is vital to correctly identifying the EPM pathogen in affected horses.

Utilities:

• Confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of N. hughesi infection.
• Ensure that herds are free of N. hughesi
• Early prevention of spread of this parasite among a herd
• Minimize personnel exposure to this parasite
• Safety monitoring of biological products and vaccines that derive from horses

References:
MacKay, R.J. (1997) Equine protozoal myeloencephalitis. Vet. Clin. North Am. Equine Pract. 13:79–96.

Specimen requirements: 1 ml whole blood in EDTA (purple top) or ACD (yellow top) tube, or 1 ml fresh plasma, serum or CSF, shipped overnight at room temperature; or 1 ml frozen plasma, serum or CSF.

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 real time PCR

Normal range: Nondetected