Comparison of prevalence factors in horses with and without seropositivity to Neospora hughesi and/or Sarcocystis neurona.
Authors: Pusterla Nicola, Tamez-Trevino Eva, White Alexandria, Vangeem Joshua, Packham Andrea, Conrad Patricia A, Kass Philip
Journal: Veterinary journal (London, England : 1997)
Summary
Equine protozoal myeloencephalitis, caused by *Sarcocystis neurona* and/or *Neospora hughesi*, remains a significant neurological concern across North America, yet the epidemiological factors distinguishing affected from unaffected horses remain poorly characterised. This large-scale serological survey analysed 3123 submissions from horses across all 49 US states, stratifying animals into four groups: *N. hughesi* seropositives (38 horses), *S. neurona* seropositives (840 horses), dual seropositives (25 horses), and seronegatives (2220 horses). Geographic location, seasonal patterns (month of submission), and breed emerged as significant variables correlating with serological status, indicating that exposure risk and susceptibility are not uniformly distributed across the equine population. These findings have direct implications for practitioners developing targeted prevention strategies—geographical risk assessment and breed-specific monitoring protocols may help identify high-risk populations, whilst seasonal submission patterns suggest temporal clustering of clinical disease that warrants further investigation into environmental or management-related triggers. Understanding these epidemiological associations enables farriers, vets, and coaches to implement contextualised biosecurity and management practices rather than adopting a one-size-fits-all approach.
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Practical Takeaways
- •S. neurona is substantially more prevalent than N. hughesi in North American horses with EPM, so consider this higher likelihood when investigating neurological disease cases
- •Geographic location and breed appear to be risk factors; practitioners should consider regional prevalence patterns when screening horses for protozoal myeloencephalitis
- •Seasonal variation in submission timing suggests temporal clustering of disease occurrence—monitor for seasonal patterns in your region to improve early detection and management
Key Findings
- •27% of submissions (840/3123) were seropositive for S. neurona only, making it the most common protozoal infection identified
- •Only 1.2% of horses (38/3123) tested seropositive for N. hughesi alone, indicating this pathogen is less prevalent than S. neurona
- •Co-infection with both N. hughesi and S. neurona occurred in less than 1% of horses (25/3123)
- •Significant associations were found between serological status and geographical location, breed, and month of submission