Equine Herpesvirus-1 Outbreak During a Show-Jumping Competition: A Clinical and Epidemiological Study.
Authors: Couroucé Anne, Normand Camille, Tessier Caroline, Pomares Rita, Thévenot Jérôme, Marcillaud-Pitel Christel, Legrand Loïc, Pitel Pierre-Hugues, Pronost Stéphane, Lupo Coralie
Journal: Journal of equine veterinary science
Summary
# Equine Herpesvirus-1 Outbreak During Show-Jumping Competition: Editorial Summary When 752 horses converged on the CES Valencia Spring Tour in 2021, an equine herpesvirus-1 (EHV-1) outbreak forced competition cancellation and site lockdown, providing researchers with a unique opportunity to characterise infection patterns and risk factors across 160 remaining horses. Through retrospective case-control analysis of 60 horses using clinical examination and quantitative PCR genotyping, the team identified the A2254 ORF30 strain and documented that 83% developed fever, 50% remained asymptomatic beyond pyrexia, and 40% progressed to neurological signs (myeloencephalopathy), with 3% mortality. Male horses proved six times more susceptible to infection overall, whilst animals over nine years old and those stabled in the centre of tents faced substantially elevated risk of developing myeloencephalopathy—findings that underscore how stable design, airflow patterns, and housing position critically influence viral transmission and disease severity. These results reinforce the importance of qPCR-based quarantine management in outbreak scenarios and provide practical evidence that equine professionals should evaluate ventilation infrastructure and stalling arrangements when designing competition facilities or managing high-risk gathering spaces.
Read the full abstract on PubMed
Practical Takeaways
- •Stable location and ventilation design significantly influence EHV-1 outbreak severity — middle tent positions showed higher neurological complication rates
- •Sex-based risk stratification may guide quarantine protocols: male horses require closer monitoring for clinical disease development
- •Rapid qPCR testing is essential for outbreak management; negative results enable evidence-based quarantine release decisions
Key Findings
- •83.3% of exposed horses (50/60) developed fever; 40% (20/60) developed neurological signs with 3% mortality
- •Stallions and geldings were 6 times more likely to develop EHV-1 infection compared to mares
- •Horses older than 9 years and those housed in the middle of the tent were more likely to develop EHM
- •EHV-1 was genotyped as A2254 (ORF30) and qPCR testing proved crucial for quarantine management