New EPM Research Sheds Light on Spread of Causative Parasite

After years of studying equine protozoal myeloencephalitis (EPM), a serious neurological disease in horses, scientists have mapped the first steps in the migratory path of Sarcocystis neurona--the chief parasitic cause of EPM.

"Before now, it was unclear how the parasite gained entry to the horse's central nervous system to cause disease," explained study co-author William Saville, DVM, PhD, Dipl. ACVIM, chair of the Department of Veterinary Preventive Medicine at The Ohio State University's College of Veterinary Medicine.

After feeding six ponies S. neurona sporocysts, the parasite was identified in abdominal lymph nodes, the liver, and lungs between Days 1 and 9 post-infection.

In addition, microscopic evidence of EPM-like lesions was found in the horses' brains and spinal cords within seven to nine days of infection.

"These results strongly suggest that the parasite spreads through lymph and blood to a number of organs, including the central nervous system, within a matter of days after exposure to S. neurona," explained Saville.

This is the first study to identify the migratory pathway of S. neurona in horses after oral infection. Further research is indicated to determine the mechanism by which the parasite is able to get into the central nervous system.

The study, "Early migration of Sarcocystis neurona in ponies fed sporocysts," was published in the Journal of Parasitology in December 2007.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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