Ahead of Print -Equine Influenza A(H3N8) Virus Isolated from Bactrian Camel, Mongolia - Volume 20, Number 12—December 2014 - Emerging Infectious Disease journal - CDC
Volume 20, Number 12—December 2014
Equine Influenza A(H3N8) Virus Isolated from Bactrian Camel, Mongolia
Since the first isolation in 1963 of an avian-origin influenza A(H3N8) virus from horses (1), subtype H3N8 influenza viruses have continued to circulate panzootically among horses, causing severe outbreaks of equine influenza respiratory disease. In the United States, these viruses jumped from horses to dogs and continue to circulate among dogs (2,3). In Mongolia, the site of some of the world’s largest epizootics of equine influenza A(H3N8) virus (EIV) infection, transmission of this virus is sustained among 2.1 million free-ranging horses, causing significant economic losses among rural herders. Major epizootics of EIV infection occurred in Mongolia during 2007–2008 (459,000 cases, 24,600 deaths) and again in 2011 (74,608 cases, 40 deaths) (4).
Over previous decades in Mongolia, outbreaks of respiratory disease, thought to be influenza, among camels have been reported. In the 1980s, the virus was characterized, and researchers speculated that it was related to a reassortant influenza A(H1N1) virus vaccine strain, A/PR-8/34 + A/USSR/77, generated in a Soviet laboratory and administered to humans in Mongolia and possibly transmitted from vaccinated humans to camels in a reactivated form (5,6). However, only 1 genetic sequence from this outbreak among camels is available in GenBank: A/camel/Mongolia/1982/H1N1. Despite reports of serologic activity against influenza A virus among camels in several African countries (7,8), the lack of isolated virus from these populations highlights how little is known about the ecology of influenza viruses in camels. Questions about the potential role of camels in human cases of Middle East respiratory syndrome (9) further highlight our lack of knowledge of infectious diseases in camels and the merits of increased surveillance at this unique human–animal interface.
Since January 2011, surveillance of equine influenza viruses has been enhanced in 3 Mongolian aimags (provinces). Surveillance among camels was also initiated in response to anecdotal reports of signs of respiratory illness in Bactrian camels (Camelus bactrianus). We describe the isolation, full-genome sequencing, and phylogenetic characterization of an influenza A(H3N8) virus of equine lineage isolated from a Bactrian camel, thereby identifying a novel route of influenza virus interspecies transmission and raising further questions about influenza A virus ecology in under-studied regions such as Mongolia.
Dr Yondon is a researcher in the Virology Laboratory at the Institute of Veterinary Medicine, Ulaanbaatar, Mongolia. His research interests include the development of new methods and technology for diagnosing, controlling, and preventing viral diseases in animals and their application in veterinary medical practice.
We thank Badarch Darmaa for her help with validating the influenza culture work.
This research was supported by multiple grants: contracts HHSN266200700005C (St. Jude Children’s Research Hospital) and HHSN272200900007C (J. Craig Venter Institute) from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, USA; R01 AI068803-ARRA supplement (G.C.G.) from the National Institute of Allergy and Infectious Diseases; and multiple grants (G.C.G.) from the US Department of Defense Armed Forces Health Surveillance Center, Global Emerging Infections Surveillance and Response Program. This research was conducted within the context of the Multinational Influenza Seasonal Mortality Study, an ongoing international collaborative effort to understand influenza epidemiology and evolution, led by the Fogarty International Center, National Institutes of Health, with funding from the Office of Global Affairs at the Department of Health and Human Services (M.I.N.).
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Suggested citation for this article: Yondon M, Zayat B, Nelson MI, Heil GL, Anderson BD, Lin X, et al. Equine influenza A(H3N8) virus isolated from Bactrian camel, Mongolia. Emerg Infect Dis [Internet]. 2014 Dec [date cited]. http://dx.doi.org/10.3201/eid2012.140435