Frequency of Detection of Respiratory Pathogens in Clinically Healthy Show Horses Following a Multi-County Outbreak of Equine Herpesvirus-1 Myeloencephalopathy in California.
Abstract: Actively shedding healthy horses have been indicated as a possible source of respiratory pathogen outbreak, transmission, and spread. Using nasal swabs from clinically healthy sport horses submitted for qPCR testing after an outbreak of equine herpesvirus-1 (EHV-1) myeloencephalopathy (EHM) in the spring of 2022, this study aimed to identify the rate of clinically healthy horses shedding common and less characterized respiratory pathogens within the sport horse population to better understand their role in outbreaks. Swabs were collected during a required quarantine and testing period, according to the United States Equestrian Federation (USEF), and showed return-to-competition requirements. Common respiratory pathogens, such as equine influenza virus (EIV), EHV-4, and equine rhinitis B virus (ERBV), were found at low but stable frequencies within previously reported ranges, whereas EHV-1 and Streptococcus equi subspecies equi (S. equi) were found at or above previously reported frequencies. Less characterized respiratory pathogens, such as EHV-2, EHV-5, and S. equi subspecies zooepidemicus (S. zooepidemicus), were found within previously reported ranges. Common respiratory pathogens, especially EHV-1 following the multiple EHM outbreaks, were found to be circulating in clinically healthy sport horse populations, reflecting their silent transmission. The strategy of quarantine and EHV-1 qPCR testing of clinically healthy horses was successful at eliminating additional EHM outbreaks and facilitating safe return to competition with no reported respiratory disease outbreaks following the subsequent shows in California.
Publication Date: 2022-10-08 PubMed ID: 36297218PubMed Central: PMC9612363DOI: 10.3390/pathogens11101161Google Scholar: Lookup
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- Journal Article
Summary
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This research paper discusses a study aimed at understanding the rate at which healthy sport horses shed respiratory pathogens after an equine herpesvirus-1 (EHV-1) outbreak in California in 2022. The objective of the study was to better understand the role of healthy horses in pathogen outbreaks. Results indicate that common respiratory pathogens are present in healthy horse populations. The implementation of a quarantine and testing strategy for EHV-1 was successful in preventing additional outbreaks.
Background of The Research
- The study was conducted in response to an outbreak of Equine Herpesvirus-1 (EHV-1) Myeloencephalopathy (EHM) in the spring of 2022. EHV-1 is a virus that causes respiratory disease in horses and can lead to severe neurological disorders.
- The researchers sought to understand the role that healthy horses may have in transmitting this virus, given that they were identified as a possible source of the outbreak.
Methodology
- Nasal swabs were taken from clinically healthy sport horses and tested using quantitative PCR (qPCR), a laboratory technique used to measure the amount of a specific RNA (or DNA) in a sample.
- This testing was conducted during a required quarantine and testing period set by the United States Equestrian Federation (USEF), following the EHV-1 outbreak.
Data Analysis and Findings
- The researchers discovered that common respiratory pathogens, such as equine influenza virus (EIV), EHV-4, and equine rhinitis B virus (ERBV), were present in the tested horses at low but consistent frequencies within previously reported ranges.
- On the other hand, EHV-1 and certain unidentified subspecies were found at or above previously reported frequencies. EHV-2, EHV-5, and other unidentified subspecies were found within previously reported ranges.
- These findings suggest that the healthy sport horse population is silently transmitting the common respiratory pathogens, especially EHV-1 following the multiple EHM outbreaks.
Implications and Conclusion
- The strategy of quarantine and EHV-1 qPCR testing of clinically healthy horses after the outbreak proved effective in preventing further EHM outbreaks. It also allowed for the safe return of the horses to competition without any new reported respiratory disease outbreaks following the subsequent shows in California.
- This study illuminates the role of healthy horses in silently transmitting the EHV-1 virus, emphasizing the need for quarantine and testing strategies to detect and control virus transmission.
Cite This Article
APA
Wilcox A, Barnum S, Wademan C, Corbin R, Escobar E, Hodzic E, Schumacher S, Pusterla N.
(2022).
Frequency of Detection of Respiratory Pathogens in Clinically Healthy Show Horses Following a Multi-County Outbreak of Equine Herpesvirus-1 Myeloencephalopathy in California.
Pathogens, 11(10).
https://doi.org/10.3390/pathogens11101161 Publication
Researcher Affiliations
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
- United States Equestrian Federation, Lexington, KY 40511, USA.
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Grant Funding
- 2022 / Boehringer Ingelheim Animal Health
- 2022 / Center for Equine Health, University of California, Davis
Conflict of Interest Statement
The authors declare no conflict of interest.
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