Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2001
Publication Date: N/A
Interpretive Summary: Sarcocystis neurona is a single-celled parasite. It causes a fatal disease in horses called EPM. Horses become infected by ingesting the resistant stage of this parasite (sporocyst) passed in feces of opossums. Scientists at the Beltsville Agricultural Research Center and the Mississippi State University investigating various risk factors associated with S. neurona infection in opossums collected from horse farms. The season and body condition were associated with increased odds of an animal harboring sporocysts. These findings will be of interest to horse owners, biologists, and parasitologists.
Technical Abstract: Sarcocystis neurona is the most important cause of equine protozoal myeloencephalitis in horses in horses in the Americas. The only known definitive host for this parasite in the United States is the opossum (Didelphis virginiana); however, despite the importance of the disease, the epidemiology of the parasite in the definitive host is poorly understood. To begin addressing these data gaps, potential risk factors were evaluated for their association with the presence of sporocysts of S. neurona in opossums live-trapped in March, 1999 and November, 1999-May, 2000. Sporocysts of S. neurona were found in 19 of the 72 animals examined. Potential risk factors evaluated were locality, trap date, age, gender, the presence of young in the pouch of females, and body condition score. Variables that were associated with the presence of S. neurona sporocysts were used in logistic regression analysis. Of the factors examined, season nand body condition score were associated with increased odds of an animal harboring sporocysts.