- Necrotising encephalomyelitis affecting the grey and white matter of the CNS
- Caused by Sarcocystis neurona
- Opossum thought to be the definitive host
- Horses thought to be accidental hosts
- Natural intermediate hosts currently unknown
- Western Blotting shows 50% of horses in the USA are seropositive
- Risk factors poorly understood
- Causes spinal cord dysfunction
- Ataxia and paralysis