Dan Howe, PhD, a professor and molecular parasitologist at the University of Kentucky Gluck Equine Research Center, and colleagues are finishing up a three-year Sarcocystis neurona genome project. The primary goal of the project, titled “Genome Sequence for the apicomplexan Sarcocystis neurona,” has been to sequence and assemble the genome of S. neurona, the protozoan (single-cell) parasite that causes protozoal myeloencephalitis (EPM) in horses.

Prior to the S. neurona genome project, Howe had been conducting preliminary sequencing studies in his lab funded by a gift from Thoroughbred breeders John and Jerry Amerman. In 2009 he received a $500,000 grant from the USDA-CSREES (U.S. Department of Agriculture-Cooperative State Research and Extension Service) competitive grants for his research.

S. neurona causes equine protozoal myeloencephalitis (EPM), which is one of the most important and commonly diagnosed neurologic diseases in the United States. EPM has a tremendous ongoing impact on the equine industry and equine health due to the considerable cost of diagnosis and care to fully recover an affected horse. Some horses might never recover entirely. Clinical signs vary from horse to horse but include loss of coordination, muscle atrophy, sore back, stumbling, locking of the stifle joint, and weakness.

The parasite’s life cycle initially begins in the definitive host, which is the opossum that passes the S. neurona oocysts and sporocysts in its feces. To complete its life cycle, this parasite needs two hosts, one definitive (final) and one intermediate