Submitted to: Journal of Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/26/2004
Publication Date: 5/24/2004
Citation: Saville, W.J., Sofaly, C.D., Reed, S.M., Dubey, J.P., Oglesbee, M.J., Lacombe, V.A., Keene, R.O., Gugisberg, K.M., Swensen, S.W., Shipley, R.D. 2004. An equine protozoal myeloencephalitis (epm) challenge model testing a second transport following inoculation with Sarcocystis neurona sporocysts. Journal of Parasitology. 90:1406-1410. Interpretive Summary: Sarcocystis neurona is a single-celled parasite that causes a fatal neurologic disease in horses, equine protozoal myeloencephalitis (EPM). It is difficult to induce EPM experimentally. Scientists at the Beltsville Agricultural Research Center and the Ohio State University report that stress can aggrevate EPM. The reuslts will be of interest to biologists, parasitologists and veterinarians.
Technical Abstract: Previous challenge studies performed at Ohio State University involved a transport-stress model where the study animals were dosed with Sarcocystis neurona sporocysts on the day of arrival. This study was to test a second transportation of horses following oral inoculation with S. neurona sporocysts. Horses were randomly assigned to groups: Group 1 were transported 4 days after inoculation (DAI); Group 2 at 11 DAI; Group 3 at 18 DAI; and Group 4 horses were not transported a second time (controls). An overall neurologic score was determined based on a standard numbering system used by veterinarians. All scores are out of 5 which is the most severely affected animal. The mean score for the Group 1 horses was 2.42; Group 2 horses was 2.5; Group 3 horses was 2.75; and Group 4 horses was 3.25. Since the Group 4 horses did not have a second transport, they were compared to all other groups. Statistically different scores were present between Group 4 and Groups 1 and 2. There were no differences in the time of seroconversion between groups. There was a difference between the time of onset of first clinical signs between Groups 1 and 4. This difference was likely due to the different examination days. Differences in housing and handling were likely the reason for the differences in severity of clinical signs. This model results in consistent, significant clinical signs in all horses at approximately the same time period post inoculation but was most severe in horses that did not experience a second transport.