Michigan EPM Studies--Exposure, Testing, Control

Research from Michigan State University (MSU) estimates that 60% of horses in the state have been exposed to Sarcocystis neurona, the parasite that causes equine protozoal myeloencephalitis (EPM). Analysis showed that seroprevalence (presence of EPM antibodies in horses) was lowest in the colder parts of the state that had the fewest opossums. Increasing age and exposure to pasture were associated with increased odds of being positive. No association was found between farm size, animal gender, hay types, horse-housing types, or exposure to natural surface water and a positive test result. Of the 1,121 horses in the study, none were currently being treated for EPM and only 10 (0.9%) had been diagnosed with EPM by a veterinarian within the past year. Researchers said that information suggests that despite high rates of exposure, relatively few horses develop clinical signs of EPM.

Several Michigan State researchers are working on projects designed to help solve the problems associated with EPM. Linda Mansfield, VMD, PhD, is head of the Emerging Parasitic Diseases Laboratory. She supplied the information for this report.

Other projects that have been done or are ongoing at MSU include the development of a new Western blot test to reduce the number of false positives. (MSU does not recommend testing of normal horses.) Another project seeks to develop a diagnostic test to detect the S. neurona parasite directly and is designed to be used in conjunction with the Western blot.

Practicing veterinarians have suggested that the daily feeding of Strongid C decreases the prevalence of EPM. Studies in the laboratory and in the field will seek to provide answers to this question. Other research is dedicated to understanding the parasite that causes EPM in order to develop vaccines and diagnostic tests. (More on this research can be found at http://www.thehorse.com/TopicSearch/Default.aspx?n=Equine+Protozoal+Myeloencephalitis+(EPM)&nID=6&ID=60.)

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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