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Viruses2025; 17(5); 612; doi: 10.3390/v17050612

Investigation of Selected Prevalence Factors Associated with EHV-2 and/or EHV-5 Infection in Horses with Acute Onset of Fever and Respiratory Signs.

Abstract: The purpose of this study was to determine any associations of EHV-2, EHV-5, and dual infection with EHV-2/-5 with demographic parameters, clinical signs, and coinfection with other common respiratory pathogens. Nasal swabs collected from 9737 horses were tested for EHV-2 and EHV-5, as well as EHV-1, EHV-4, EIV, , ERAV, and ERBV, by qPCR. Clinical signs and demographic parameters were recorded, and prevalence factors were evaluated for significance regarding EHV-2 and/or EHV-5 infection. Out of the 9737 horses in this study, 17.8% tested EHV-2-positive ( = 1731), 15.8% tested EHV-5-positive ( = 1536), 33.4% tested positive for both viruses EHV-2/-5 ( = 3247), and 33.1% tested negative for both viruses ( = 3223). When comparing EHV-2 and/or EHV-5 infected horses to horses testing qPCR-negative for both viruses, horses infected with EHV-2 alone were more likely to be younger Thoroughbreds with a history of recent transportation, presenting with fever, and having a higher rate of coinfections with EHV-4 and . Horses infected with EHV-5 alone were less likely to be used for pleasure purposes, had fewer clinical signs, and were more likely to be coinfected with EHV-4. Horses dually infected with EHV-2 and EHV-5 were much more likely to be younger, used for competition, presenting with a fever, and coinfected with additional respiratory pathogens. It is apparent from the study population that horses infected with EHV-2 alone or in combination with EHV-5 had breed predilections, greater frequency of clinical signs, and a higher rate of coinfections with EHV-4, ERBV, and .
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Publication Date: 2025-04-25 PubMed ID: 40431624PubMed Central: PMC12116073DOI: 10.3390/v17050612Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study examined the relationship of EHV-2 and EHV-5 infections with demographic and clinical factors in horses. It found that factors such as age, breed, employment (competition or pleasure), recent transport and co-infections had a significant bearing on the prevalence of these infections.

Research methodology

  • The study aimed to identify any connections between infection with EHV-2, EHV-5, or both, and certain demographic factors, clinical indicators, and coexistence with other common respiratory pathogens.
  • Nasal swabs from 9,737 horses were examined for EHV-2, EHV-5, EHV-1, EHV-4, EIV, ERAV, and ERBV using quantitative Polymerase Chain Reaction (qPCR).
  • Various clinical signs and demographic data were noted, and prevalence factors were checked for their significance in relation to EHV-2 and/or EHV-5 infection.

Findings

  • Of the horses included, 17.8% tested positive for EHV-2, 15.8% for EHV-5, 33.4% for both viruses and 33.1% were free of both viruses.
  • Comparing the horses that tested positive for either or both viruses to those that were negative for both, revealed that horses with only EHV-2 were likely to be younger Thoroughbreds that had recently been transported and presented with fever. This group also had a high rate of co-infections with EHV-4.
  • Horses infected solely with EHV-5 were less likely to be used for pleasure riding, had fewer clinical signs, and also had a higher incidence of EHV-4 co-infection.
  • Horses infected with both EHV-2 and EHV-5 were more likely to be younger, used for competition, showing symptoms of fever, and be co-infected with other respiratory pathogens.

Conclusion

  • The research data indicates that horses with EHV-2 infection, either alone or in concert with EHV-5, had breed preferences and showed clinical signs more frequently.
  • These horses also had a higher co-infection rate with pathogens EHV-4, ERBV, and .
  • These findings suggest that demographic factors like age, breed, purpose of use and recent transportation, as well as co-infections with other respiratory pathogens, play a significant role in the susceptibility of horses to EHV-2 and EHV-5 infections.

Cite This Article

APA
James K, Chappell DE, Craig B, Pariseau C, Wright C, van Harreveld P, Barnum S, Pusterla N. (2025). Investigation of Selected Prevalence Factors Associated with EHV-2 and/or EHV-5 Infection in Horses with Acute Onset of Fever and Respiratory Signs. Viruses, 17(5), 612. https://doi.org/10.3390/v17050612

Publication

Viruses
ISSN: 1999-4915
NlmUniqueID: 101509722
Country: Switzerland
Language: English
Volume: 17
Issue: 5
PII: 612

Researcher Affiliations

James, Kaitlyn
  • Department of Obstetrics, Gynecology and Reproduction Biology, Massachusetts General Hospital, Boston, MA 02114, USA.
Chappell, Duane E
  • Merck Animal Health, Rahway, NJ 07065, USA.
Craig, Bryant
  • Merck Animal Health, Rahway, NJ 07065, USA.
Pariseau, Chrissie
  • Merck Animal Health, Rahway, NJ 07065, USA.
Wright, Cara
  • Merck Animal Health, Rahway, NJ 07065, USA.
van Harreveld, Philip
  • Merck Animal Health, Rahway, NJ 07065, USA.
Barnum, Samantha
  • Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Pusterla, Nicola
  • Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.

MeSH Terms

  • Animals
  • Horses
  • Horse Diseases / virology
  • Horse Diseases / epidemiology
  • Prevalence
  • Herpesviridae Infections / veterinary
  • Herpesviridae Infections / epidemiology
  • Herpesviridae Infections / virology
  • Coinfection / veterinary
  • Coinfection / virology
  • Coinfection / epidemiology
  • Male
  • Female
  • Fever / veterinary
  • Fever / virology
  • Fever / epidemiology
  • Respiratory Tract Infections / veterinary
  • Respiratory Tract Infections / virology
  • Respiratory Tract Infections / epidemiology

Grant Funding

  • 000 / Merck Animal Health

Conflict of Interest Statement

N.P., S.B., and K.J. declare no conflicts of interest. D.E.C., B.C., C.P., C.W., and P.v.H currently work for Merck Animal Health, Rahway, NJ, USA.

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