An equine protozoal myeloencephalitis challenge model testing a second transport after inoculation with Sarcocystis neurona sporocysts.

The study evaluates the impact of a second transportation on horses infected with Sarcocystis neurona sporocysts, a parasite causing equine protozoal myeloencephalitis (EPM). The research shows that horses subjected to a second transport exhibited less severe symptoms compared to those not transported a second time.

Research Methodology

• The researchers used a transport-stress model that was previously conducted at Ohio State University. In this model, study animals were exposed to the parasite Sarcocystis neurona sporocysts immediately upon arrival.
• In this study, the horses were subjected to a second transportation event after being infected with the parasite.
• The horses were arbitrarily divided into four groups. Group 1 was transported 4 days after infection, Group 2 at 11 DAI, Group 3 at 18 DAI, and Group 4 served as a control group and did not undergo a second transport.

Results and Analysis

• A neurological score was used to assess the severity of the disease in the horses, with 5 being the most severely affected.
• The mean scores for Groups 1, 2, 3, and 4 were 2.42, 2.5, 2.75, and 3.25 respectively. Given that Group 4 did not experience a second transport, its score was compared with scores of the other groups.
• Statistical analysis revealed significant differences between Group 4 and Groups 1 and 2, with Group 4 exhibiting more acute symptoms.
• No significant differences were identified in the time of seroconversion (the period from infection to the presence of detectable antibodies in the blood) between the groups.
• However, differences were seen in the onset of the first clinical signs between Group 1 and Group 4, which was likely due to varying examination days.
• Differences in housing and handling were proposed as potential contributing factors to the variations in symptom severity.

Conclusions

• The study found that the model resulted in consistent, significant clinical signs in all horses around the same period post-infection.
• The most severe symptoms were seen in horses that did not undergo a second transport, implying that stress from multiple transports may mitigate the severity of the parasitic infection to some extent.