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Equine veterinary journal2020; 52(4); 509-515; doi: 10.1111/evj.13210

Annual booster vaccination and the risk of equine influenza to Thoroughbred racehorses.

Abstract: Equine influenza (EI) outbreaks occurred among horses on four racing yards (two National Hunt, one Flat, one mixed National Hunt racing/breeding yard) in Ireland within a 4-week period. Objective: To carry out a detailed analysis of racing yards affected in order to identify the source of infection and monitor virus spread among a vaccinated population. Methods: Observational field study. Methods: Epidemiological and vaccination data along with repeat clinical samples were collected from 118 horses on four premises. Results: Failure to implement appropriate biosecurity measures following the introduction of new arrivals and the return of horses from equestrian events contributed to disease spread as did the movement of horses within premises. Mixing of racing and non-racing populations with inadequate vaccination histories also facilitated virus transmission. The index case(s) on all premises was vaccinated in accordance with the Turf Club rules. Vaccine breakdown was observed across all products in 27/80 horses (33.8%) with an up-to-date vaccination record. Eighteen of the 27 (66.7%) horses had not received a booster vaccination within the previous 6 months and 10 (37%) horses were due annual booster vaccination at the time of developing clinical signs. Conclusions: The interpretation of laboratory results followed a delay in veterinary intervention. Conclusions: Annual booster vaccination should not be relied on as the sole preventative measure against EI. The findings of this study suggest that increasing the frequency of booster vaccinations may be beneficial particularly in young horses and that synchronised scheduling of vaccination regimes across racing yards may contribute to high-risk periods for EI virus (EIV) transmission.
Publication Date: 2020-02-12 PubMed ID: 31750956DOI: 10.1111/evj.13210Google Scholar: Lookup
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  • Journal Article
  • Observational Study
  • Veterinary

Summary

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The research investigates how the failure to uphold appropriate biosecurity measures and a dependence on annual booster vaccinations contributed to equine influenza (EI) outbreaks among Thoroughbred racehorses in Ireland. The study indicates that additional preventative measures, such as increased frequency of booster vaccinations, especially for young horses, might be more effective against EI.

Methodology

  • The research is an observational field study conducted on four racing yards in Ireland where EI outbreaks occurred within a four-week period.
  • The researchers gathered epidemiological and vaccination data as well as clinical samples from 118 horses across the aforementioned four premises.

Findings

  • The study found that the absence of biosecurity measures following the introduction of new arrivals and the return of horses from events played a significant role in the spread of the disease. Movement of horses within the premises was also found to facilitate transmission of the virus.
  • The mixing of racing and non-racing horses with inadequate vaccination histories was identified as another factor contributing to virus transmission.
  • Interestingly, the first identified cases (the index cases) in all premises had been vaccinated following the Turf Club rules. However, vaccine failure was observed in 33.8% of the horses that had up-to-date vaccination records. Furthermore, 66.7% of these horses had not received a booster vaccination within the preceding 6 months and 37% were due for their annual booster vaccination when they started showing clinical signs of EI.

Conclusion

  • The researchers concluded that annual booster vaccinations alone should not be the sole preventative measure against EI.
  • They also warned that there was a delay in the interpretation of laboratory results due to late veterinary intervention, which could have implications for controlling an outbreak.
  • Based on their observations, the researchers suggested that more frequent booster vaccinations, especially for young horses, could be beneficial. They also proposed that synchronising vaccination schedules across racing yards might mitigate periods of high-risk virus transmission.

Cite This Article

APA
Gildea S, Lyons P, Lyons R, Gahan J, Garvey M, Cullinane A. (2020). Annual booster vaccination and the risk of equine influenza to Thoroughbred racehorses. Equine Vet J, 52(4), 509-515. https://doi.org/10.1111/evj.13210

Publication

ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 52
Issue: 4
Pages: 509-515

Researcher Affiliations

Gildea, Sarah
  • Virology Unit, The Irish Equine Centre, Johnstown, Naas, Kildare, Ireland.
Lyons, Pamela
  • Virology Unit, The Irish Equine Centre, Johnstown, Naas, Kildare, Ireland.
Lyons, Rachel
  • Virology Unit, The Irish Equine Centre, Johnstown, Naas, Kildare, Ireland.
Gahan, Jacinta
  • Virology Unit, The Irish Equine Centre, Johnstown, Naas, Kildare, Ireland.
Garvey, Marie
  • Virology Unit, The Irish Equine Centre, Johnstown, Naas, Kildare, Ireland.
Cullinane, Ann
  • Virology Unit, The Irish Equine Centre, Johnstown, Naas, Kildare, Ireland.

MeSH Terms

  • Animals
  • Horse Diseases
  • Horses
  • Influenza Vaccines
  • Influenza, Human
  • Ireland
  • Orthomyxoviridae Infections / veterinary
  • Vaccination / veterinary

Grant Funding

  • OIE/2014 / Department of Agriculture Food and the Marine

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Citations

This article has been cited 7 times.
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