wildlife and zoo assay data sheet
agent of equine protozoal myeloencephalitis (EPM)
X0004 - Ultrasensitive qualitative detection of
by real time polymerase chain reaction
protozoal myeloencephalitis (EPM), also known as "equine
protozoa myelitis" is primarily caused by the apicomplexan
parasite Sarcocystis neurona. EPM is the most commonly diagnosed
neurologic disease of the horse in the US (Dubey et al., 2001).
Based on reported surveys from individual horse owners, EPM has
been labeled as the most important infectious disease facing the
equine industry ( NAHMS, 2001). Several surveys conducted in
Ohio have revealed greater than 50% (53.6%) of horses with
circulating S. neurona
antibodies (Saville et al., 1997). Opossums (Didelphis
virginiana) serve as definitive hosts for
S. neurona in the US
and are responsible for shedding infective
sporocysts (Fenger et al., 1997; Dubey and Lindsay, 1998).
However, it is not clear how the opossum became infected because
hosts harboring sarcocysts have not been identified. Recently,
sarcocysts have been identified in the muscles of cats,
raccoons, armadillos, sea otters and skunks. Recent studies from
Michigan and Florida have reported
antibodies in 5% of domestic cats. A subsequent study has
confirmed domestic cats to be natural carriers of this parasite
(Stanek et al., 2003).
an aberrant intermediate host of
Sporocysts are eaten, pass into the small intestine and excyst
there. The infective stage of the organism, the sporozoite, then
enters the horse's blood stream. In some horses, these undergo
several replicative cycles in endothelial cells (in blood
vessels), becoming tachyzoites, and migrate to the central
nervous system. They replicate asexually within neurons and
microglial cells without forming tissue cysts. In the central
nervous system of the horse, they slowly divide and grow,
gradually destroying the nervous tissue, causing incoordination
and the other clinical signs that result from EPM. At this
stage, the organism found in horses cannot be transmitted to
other horses. Because the organism does not encyst in horse
tissues, it cannot be transmitted to opossums, even if an
opossum were to eat the tissue. Therefore, the horse is a dead
end host for the protozoan.
Help confirm the disease causing agent
Shorten the time required to confirm a clinical
diagnosis of S. neurona
Help ensure that animal populations are free of
Early prevention of spread of this protozoan
Minimize human exposure to this protozoan
Safety monitoring of biological products that derive
from host animals
Dubey, J.P. and Lindsay, D.S. (1998) Isolation in
immunodeficient mice of Sarcocystis neurona from opossum (Didelphis
virginiana) faeces, and its differentiation from Sarcocystis
falcatula. Int. J. Parasitol. 28:1823–1828..
Lindsay, D.S., Saville, W.J.A., Reed, S.M., Granstrom, D.E. and
Speer, C.A. (2001) A review of Sarcocystis neurona and equine
protozoal myeloencephalitis (EPM). Vet. Parasitol. 95: 89–131.
Fenger, C.K., Granstrom, D.E., Langemeier, J.L. and Stamper,
S. (1997) Epizootic of equine protozoal myeloencephalitis on a
farm. J. Am. Vet. Med. Assoc 210: 923–927.
Equine Protozoal Myeloencephalitis (EPM) in the US. APHIS:VS,
CEAH, National Animal Health Monitoring System. USDA, Fort
Saville, W.J.A., Reed, S.M., Granstrom, D.E.,
Hinchcliff, K.W., Kohn, C.W., Wittum, T.E. and Stamper, S.
(1997) Prevalence of serum antibodies to Sarcocystis neurona in
horses residing in Ohio. J. Am. Vet. Med. Assoc. 210:519–524.
Stanek, J.F., Stich, R.W., Dubey, J.P., Reed, S.M., Njoku, C.J.,
Lindsay, D.S., Schmall, L.M., Johnson, G.K., LaFave, B.M. and
Saville, W.J. (2003) Epidemiology of Sarcocystis neurona
infections in domestic cats (Felis domesticus) and its
association with equine protozoal myeloencephalitis (EPM) case
farms and feral cats from a mobile spay and neuter clinic. Vet
Specimen requirements: 0.2 ml whole blood in EDTA (purple top) or ACD (yellow top)
tube, or 0.2 ml CSF, or 0.2 ml fresh, frozen or fixed CNS
tissue, or 0.2 ml feces from opossum or other carrier species.
types other than those listed here, please call to confirm
specimen acceptability and shipping instructions.
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.
2 business days
real time PCR