MSU research zeroes in on EPM

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Aug 01, 2001
By dvm360.com staff

East Lansing, Mich.-At least six of every 10 horses in the state of Michigan have been exposed to Sarcocystis neurona, the parasite responsible for Equine Protozoal Myeloencephalitis (EPM), according to study results from researchers at Michigan State University.

Researchers at the Emerging Parasitic Diseases Laboratory at Michigan State University, headed by Linda Mansfield, VMD, Ph.D., launched the EPM study after being approached by horse producer groups within the state who listed EPM as their number one disease concern.

According to Mansfield, the study proved that the most significant contributing factor to the prevalence of EPM were opossums.

"There was this dramatic correlation with the prevalence of opossums and the prevalence of the disease," Mansfield tells DVM Newsmagazine. "It is very clear that the majority of horses are living in the areas with the majority of opossums in the southern tier of the state. Those have been traditionally the horse rearing areas."

The presence of EPM antibodies in horses was less common in colder areas in the state, which had less opossums.

Probable reasons for exposure include increased exposure to pasture. Factors such as farm size, animal gender, hay types or exposure to water seemed to have no influence on test results.

Researchers tested 1,121 horses, and of those, none were presently being treated for EPM and only 10 were diagnosed by a veterinarian within the last year.