Researchers have discovered that the striped skunk serves as an intermediate host for Sarcocystis neurona, the single-celled protozoan parasite that causes the neurological disease equine protozoal myeloencephalitis (EPM) in horses. The striped skunk’s range of habitat encompasses much of the United States, Canada, and northern Mexico, so this discovery better explains the wide geographic distribution of EPM. The results of this project follow a previous one that identified the nine-banded armadillo as a natural intermediate host for EPM.

This study involved the collaboration of various researchers from different institutions. Ellis Greiner, PhD, Andy Cheadle, Charles Yowell, Pamela Ginn, DVM, Robert MacKay, BVSc, PhD, Dipl. ACVIM, and John B. Dame, PhD, worked from the University of Florida. Debra Sellon, DVM, PhD, Dipl. ACVIM, and Melissa Hines, DVM, PhD, Dipl. ACVIM, worked on the study from Washington State University, and Antoinette E. Marsh, PhD, contributed from the University of Missouri. Greiner, who is a professor in the Department of Pathobiology at the UF’s College of Veterinary Medicine said, “We were looking at a variety of aspects of (S. neurona), and how it interacts with the horse, skunk, and opossums. Major research contributions are made this day and age by teams—I don’t think any of us could do this type of thing alone.”

In this study, striped skunks initially negative for antibodies to S. neurona were inoculated with the parasite collected from a naturally infected opossum. Skunks developed antibodies to S. neurona, sarcocysts developed in their muscles, and the muscles were fed to laboratory-reared opossums that then shed sporocysts in their feces. A pony foal and laboratory mice were inoculated with the sporocysts. The foal developed antibodies to S. neurona in the central nervous system fluid. The mice all developed antibodies and central nervous system disease and died or had to be euthanized.

“The beauty of it is that this fills out the rest of S. neurona’s range for North America and explains how opossums could be infected where we don’t have armadillos,” explained Greiner. The domestic cat also has been identified as an intermediate host in the laboratory, although it hasn’t been proven that the cat serves as a natural intermediate host