A Brief Introduction to Equine Influenza and Equine Influenza Viruses.
Abstract: Equine influenza virus (EIV) is a common respiratory pathogen of horses and other equids in most parts of the world. EIV are Type A influenza viruses and two subtypes are known: H3N8 and H7N7. Both are believed to have evolved from avian influenza virus ancestors. The H3N8 subtype circulates widely, but the H7N7 subtype is thought to be extinct. The clinical disease in horses, caused by either subtype, is an upper respiratory infection of varying severity depending upon the immune status of the individual animal. It is not normally life-threatening in itself except in very young foals; however it predisposes infected equids to secondary infections capable of producing life-threatening pneumonias. Vaccines are available and widely used in some horse populations, but their effectiveness is limited by antigenic drift and other factors, and vaccinated animals with subclinical infections have been responsible for introduction of EIV into susceptible populations. EIV has spread into canines.
Publication Date: 2020-03-15 PubMed ID: 32170701DOI: 10.1007/978-1-0716-0346-8_26Google Scholar: Lookup
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Summary
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This research article examines the nature of Equine Influenza Virus (EIV) and its subtypes H3N8 and H7N7, their origin, effects on horses and other equids, and the apparent limitations in the efficacy of available vaccines. The study also highlights the transmission of EIV to canines.
Understanding Equine Influenza Virus
- Equine Influenza Virus is a prevalent respiratory pathogen affecting horses and other animals belonging to the equid family across the globe.
- This article discusses how EIV comes from the family of Type A influenza viruses and exists in two subtypes: H3N8 and H7N7. These subtypes are believed to have evolved from avian influenza virus ancestors.
- The more commonly found subtype H3N8 is widely prevalent, while the H7N7 subtype is considered extinct.
Clinical Manifestation and Impact
- When contracted by horses, both subtypes of the EIV can cause a respiratory infection which varies in severity depending on the animal’s immunity.
- While the disease itself is not generally life-threatening except in very young foals, EIV can leave the infected equids more vulnerable to secondary infections. This could result in life-threatening pneumonias.
Limited Efficacy of Vaccines
- The study indicates that while vaccines against EIV are available and are often administered in some horse populations, their effectiveness has been seen to be limited.
- Factors such as antigenic drift (changes in the virus that may make the vaccine less effective over time) and others are believed to be responsible for this limited effectiveness.
- It has been observed that vaccinated animals with subclinical infections could potentially introduce EIV to susceptible populations, thus posing a risk.
Transmission to Canines
- Lastly, the study illuminates the concern regarding the transmission of EIV to canines, demonstrating the virus’s capability of spreading across different species.
Cite This Article
APA
Chambers TM.
(2020).
A Brief Introduction to Equine Influenza and Equine Influenza Viruses.
Methods Mol Biol, 2123, 355-360.
https://doi.org/10.1007/978-1-0716-0346-8_26 Publication
Researcher Affiliations
- Department of Veterinary Science, Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY, USA. tmcham1@uky.edu.
MeSH Terms
- Animals
- Horse Diseases / epidemiology
- Horse Diseases / immunology
- Horse Diseases / transmission
- Horse Diseases / virology
- Horses / virology
- Influenza A Virus, H3N8 Subtype / physiology
- Influenza A Virus, H7N7 Subtype / physiology
- Orthomyxoviridae Infections / immunology
- Orthomyxoviridae Infections / transmission
- Orthomyxoviridae Infections / veterinary
- Orthomyxoviridae Infections / virology
- Population Surveillance
- Vaccination / veterinary
Citations
This article has been cited 13 times.- Gonzalez-Obando J, Forero JE, Zuluaga-Cabrera AM, Ruiz-Saenz J. Equine Influenza Virus: An Old Known Enemy in the Americas. Vaccines (Basel) 2022 Oct 14;10(10).
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- Li X, Liu J, Qiu Z, Liao Q, Peng Y, Chen Y, Shu Y. Host-Adaptive Signatures of H3N2 Influenza Virus in Canine. Front Vet Sci 2021;8:740472.
- Altan E, Hui A, Li Y, Pesavento P, Asín J, Crossley B, Deng X, Uzal FA, Delwart E. New Parvoviruses and Picornavirus in Tissues and Feces of Foals with Interstitial Pneumonia. Viruses 2021 Aug 14;13(8).
- Alnaeem A, Shawaf T, Ali AM, Hemida MG. Clinical observations and molecular detection of Type-A influenza virus in some of the family Equidae in eastern Saudi Arabia winter-2019. Vet Res Commun 2021 Dec;45(4):423-430.
- Bruno L, Nappo MA, Frontoso R, Montinaro S, Di Lecce R, Guarnieri C, Ferrari L, Corradi A. Avian Influenza Viruses: Global Panzootic, Host Range Expansion and Emerging One-Health Threats. Vet Sci 2026 Jan 9;13(1).
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- Gonzalez-Obando J, Jaimes-Dueñez J, Zuluaga-Cabrera A, Forero JE, Diaz A, Rojas-Arbeláez C, Ruiz-Saenz J. Seroprevalence of Equine Influenza Virus Antibodies in Horses from Four Localities in Colombia. Viruses 2025 Jul 16;17(7).
- Spruit CM, Palme DI, Li T, Ríos Carrasco M, Gabarroca García A, Sweet IR, Kuryshko M, Maliepaard JCL, Reiding KR, Scheibner D, Boons G-J, Abdelwhab EM, de Vries RP. Complex N-glycans are important for interspecies transmission of H7 influenza A viruses. J Virol 2024 Apr 16;98(4):e0194123.
- Ricci I, Tofani S, Lelli D, Vincifori G, Rosone F, Carvelli A, Diaconu EL, La Rocca D, Manna G, Sabatini S, Costantini D, Conti R, Pacchiarotti G, Scicluna MT. First Reported Circulation of Equine Influenza H3N8 Florida Clade 1 Virus in Horses in Italy. Animals (Basel) 2024 Feb 12;14(4).
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- van der Vossen N, Cavalcante P, Glynn S, Achappa D, Mehmood W, Oikawa M, Vinardell T, Jamieson C. A case-control study of atypical guttural pouch empyema in Arabian foals. Vet Med Sci 2023 Jul;9(4):1599-1609.
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