Early migration of Sarcocystis neurona in ponies fed sporocysts.

This research aims to understand how Sarcocystis neurona, a parasite causing neurological disorders in horses, spreads within its host’s body. The study suggests that this parasite disseminates relatively quickly in naive ponies’ tissue following oral inoculation.

Introduction to the Research

• The study focuses on Sarcocystis neurona, a parasite known to cause equine protozoal myeloencephalitis (EPM), a serious neurological disease in horses.
• The primary goal is to understand the kinetics of S. neurona invasion or how rapidly this parasite spreads within the equine model after the ponies are orally exposed to it.

Methodology

• Six ponies were orally inoculated with a substantial amount of S. neurona sporocysts – the infective stage of the parasite – through a nasogastric tube.
• The ponies were euthanized at different intervals post-inoculation (1, 2, 3, 5, 7, and 9 days) for analyzing the spread of the parasite within their bodies.
• At the time of necropsy, tissue samples from various body parts were procured for testing.

Findings

• The researchers found S. neurona in the mesenteric lymph nodes – an integral part of the immune system situated in the abdominal region – at days 1, 2, and 7 post-inoculation.
• The parasite was discovered in the liver on days 2, 5, and 7 and in the lungs on days 5, 7, and 9, using bioassays in interferon gamma gene knock out mice and from cell culture.
• Microscopic lesions suggestive of EPM infection were noticed in the brain and spinal cord of ponies euthanized at 7 and 9 days post-inoculation.

Conclusion

• The evidence suggests that in naive ponies – those without prior exposure or immunity to Sarcocystis neurona – the parasite disseminates quickly across various tissues.
• The presence of the parasite in the mesenteric lymph nodes early on and its subsequent appearance in the liver and lungs indicate its rapid spread. Its presence in the brain and spinal cord, resulting in EPM infection, reflects its neuro-invasive nature.