Fatal West Nile Virus Infection in Horse Returning to United Kingdom from Spain, 2022.

Fatal West Nile Virus Infection in a Horse Returning to the United Kingdom from Spain in 2022 highlights a case of a fatal infection in a horse that had traveled from an area where the virus is prevalent. This study emphasizes the importance of vaccinating horses against West Nile Virus when traveling to endemic regions.

Overview of the Case

• A 7-year-old mare was infected with West Nile Virus (WNV) after returning from Spain to the United Kingdom in 2022.
• The infection resulted in a fatal outcome for the horse.
• Timing of the infection and genetic analysis of the virus suggest the horse contracted the virus in Andalusía, a region in southern Spain known to be endemic for WNV.

Significance of the Virus and Its Transmission

• West Nile Virus is a mosquito-borne flavivirus that can infect birds, humans, and horses.
• In horses, WNV infection can lead to neurological disease and sometimes fatal outcomes.
• The virus is endemic in parts of southern Europe, including Andalusía, Spain, and poses risks to unvaccinated animals traveling in these regions.

Case Timeline and Molecular Analysis

• The infected horse had recently traveled from Spain back to the United Kingdom when symptoms and infection were detected.
• Molecular sequencing of the virus isolated from the horse showed close genetic similarity to recent WNV isolates from Andalusía.
• This clustering supports the conclusion that the horse contracted the infection during its stay in Spain, rather than in the UK.

Implications for Equine Health and Travel

• The case underscores the risk of WNV infection in horses traveling from endemic areas to non-endemic countries.
• It highlights the critical importance of vaccination against WNV prior to travel to reduce the risk of infection and fatal illness.
• Veterinarians and horse owners should consider implementing vaccination protocols as part of travel and biosecurity measures for horses going to or returning from WNV-endemic regions.
• Continued surveillance and viral monitoring are essential for early detection and response to WNV cases in non-endemic countries, especially those importing animals from endemic regions.

Conclusion

• This report describes the first fatal West Nile virus infection in a horse returning to the UK from Spain in 2022.
• The findings reinforce the need for preventive measures such as vaccination and monitoring to protect equine health against WNV.