The Sweet Nile Virus: Understanding Its Prevalence in Horses

West Nile virus, also known as WNV, is a single-stranded RNA virus that can cause neurological diseases in both humans and horses. As a notifiable disease in horses within the UK, it is essential to understand its prevalence in the equine population. A recent study conducted in South East England aimed to investigate the seroprevalence of WNV in resident horses.

A total of 988 serum samples were collected from horses between August and November 2019 through the Animal and Plant Health Agency's equine testing service. The samples were tested using two enzyme-linked immunosorbent assays (ELISAs) to detect both flavivirus antibodies and WNV-specific immunoglobulin M (IgM) antibodies.

The results showed that 274 samples tested positive for flavivirus antibodies, with two of these samples subsequently testing positive for WNV-specific IgM antibodies. However, upon further investigation, it was found that all IgM-seropositive cases were due to previous vaccination, rather than recent infection.

Interestingly, a significant proportion of the UK equine population may be susceptible to WNV infection, as 714 samples tested negative for WNV-specific antibodies. This highlights the importance of considering vaccination history when interpreting serological test results in horses.

The study's findings suggest that there is no evidence of cryptic WNV infection in the sampled cohort of horses. Moreover, all positive ELISA results were found to be due to previous vaccination, rather than recent infection. These results are significant for future epidemiological surveys, as they demonstrate the importance of knowing a horse's clinical history when distinguishing between vaccinated and infected animals.

The study's authors conclude that while WNV is not endemic in the UK, it is essential to remain vigilant due to the potential movement of competent vectors and viraemic hosts. As vaccines against WNV are commercially available within the UK, it is crucial for equine owners and veterinarians to be aware of the virus and its potential impact on horse health.

In summary, this study provides valuable insights into the seroprevalence of WNV in the UK equine population. While there may be a significant proportion of susceptible horses, vaccination can provide protection against infection. As WNV is a notifiable disease in horses within the UK, it is essential to remain informed about its prevalence and take steps to prevent outbreaks.

Weet nile virus