Equine Encephalosis Virus.
Authors: Tirosh-Levy Sharon, Steinman Amir
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Equine Encephalosis Virus Equine encephalosis virus (EEV) is a Culicoides-borne Orbivirus that causes acute febrile disease in horses without direct horse-to-horse transmission, with seven distinct serotypes recognised within the serogroup. First documented in South Africa in 1967, EEV remained geographically contained until its detection in Israel during 2008–2009, with retrospective serological analysis revealing the pathogen had actually been circulating beyond southern Africa since at least 2001. Whilst EEV typically presents as a relatively mild clinical condition, its significance lies in serving as a sentinel for the geographic expansion of related and considerably more pathogenic viruses, particularly African horse sickness virus (AHSV), and its emergence in the Middle East, central Africa and India mirrors patterns seen with West Nile virus expansion. This review by Tirosh-Levy and Steinman synthesises current understanding of EEV epidemiology, structure, pathogenesis and clinical presentation across affected regions. Practitioners should broaden diagnostic considerations when confronted with clusters of febrile cases or suspected arboviral outbreaks, as EEV's geographic range expansion demonstrates how established geographic boundaries for equine pathogens can rapidly shift, with important implications for biosecurity protocols and disease surveillance strategies.
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Practical Takeaways
- •Include EEV in differential diagnosis when investigating febrile or neurological cases in horses, particularly in geographic regions beyond traditional southern African endemic areas
- •Recognize EEV emergence as an indicator of changing pathogen distribution patterns; maintain vigilance for other related arboviruses like AHSV that may follow similar epidemiological trajectories
- •Implement vector control measures targeting Culicoides midges where EEV is confirmed or suspected to reduce transmission risk
Key Findings
- •Equine encephalosis virus has seven identified serotypes (EEV-1-7) within the Orbivirus genus of Reoviridae family transmitted by Culicoides vectors
- •EEV emerged from South Africa to the Middle East, central Africa, and India between 2001-2009, with retrospective serology confirming circulation outside South Africa since 2001
- •Although EEV typically causes mild clinical disease, its emergence signals potential spread of more pathogenic related viruses such as African horse sickness virus