West Nile Virus in Horses as a Sentinel Host in One Health Surveillance: Epidemiological Insights and Future Perspectives.

Overview

• This research article explores the role of horses as sentinel hosts in detecting West Nile virus (WNV) circulation, highlighting their importance in One Health surveillance to understand and control the spread of this mosquito-borne virus.

Introduction to West Nile Virus and Equine Hosts

• West Nile virus (WNV) is a mosquito-transmitted virus found worldwide that affects both animals and humans.
• Horses, although they do not contribute to spreading the virus (dead-end hosts), can signal the presence of WNV when they are exposed to mosquito bites.
• This sentinel role is valuable because horses often live in consistent geographical locations and interact regularly with mosquito vectors.

Reasons Horses Are Effective Sentinel Hosts

• Frequent Exposure: Horses encounter mosquitoes regularly, increasing chances to detect virus circulation.
• Measurable Immune Response: Horses develop detectable antibodies after WNV infection, which can be measured to identify virus presence.
• Geographical Stability: Horses usually remain within defined areas, providing localized data on virus activity.
• Accessibility: Horses are managed by owners and veterinarians making sample collection and monitoring more feasible.
• Integration within One Health Framework: The use of equine data ties animal, vector, and human health surveillance together effectively.

Evidence Supporting Equine Surveillance

• Research in Europe and the Americas has shown that seroprevalence studies in horses can:
• Identify geographic hotspots of WNV transmission.
• Reveal silent virus circulation where clinical cases in humans or animals are not yet apparent.
• Help understand temporal patterns of virus activity related to seasons or environmental changes.

Challenges and Limitations of Equine Sentinel Surveillance

• Vaccination Effects: Horses vaccinated against WNV produce antibodies making it difficult to distinguish between natural infection and vaccination-induced immunity.
• Flavivirus Cross-Reactivity: Antibodies against other flaviviruses can cross-react with WNV tests, complicating accurate diagnosis.
• Methodological Variability: Differences in testing protocols and data collection methods reduce comparability across different studies or regions.
• Ecological Context: Variation in local ecology, vector species, and horse management affect the interpretation of serological data.

Future Perspectives and Recommendations

• Enhance equine surveillance by adopting standardized diagnostic and monitoring methodologies to ensure consistent data quality.
• Integrate equine serological data with geospatial mapping and predictive modeling to improve early warning systems for WNV outbreaks.
• Leverage One Health approaches by coordinating veterinary, entomological, and human public health efforts for comprehensive arboviral disease control.
• Invest in further research to refine interpretation of antibody responses, especially in vaccinated populations or in regions with multiple circulating flaviviruses.
• Use sentinel surveillance in horses as part of a broader strategy to monitor and control emerging arboviral diseases beyond WNV.