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  • The Equine Flu in South America

    Patricia F. Favaro 1   Leonardo J. Richtzenhain 1  

    1 Department of Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Science (FMVZ), University of São Paulo (USP), São Paulo - SP, Brazil

    Author Contributions
    Received 02 Aug 2018; Accepted 20 Aug 2018; Published 30 Aug 2018;

    Copyright ©  2018 Patricia F. Favaro. et al.

    Creative Commons License     This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

    Competing interests

    The authors have declared that no competing interests exist.


    Patricia F. Favaro, Leonardo J. Richtzenhain (2018) The Equine Flu in South America. Journal of Air and Water Borne Diseases - 1(1):1-3.

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    In the pre-virological era equine flu outbreaks were described based on clinical signs and on disease spreading pattern. Human flu cases were also described concomitant with those animal outbreaks. By that time there was none/or little knowledge about the agent that was causing those clinical signs in humans and animals. The equine influenza (EI) would cause serious impact in cities where horses were the major type of transportation1.

    With science evolution, the agent that was causing flu was first identified from pigs2, from humans in 19333 and from equines in 1956 (H7N7 subtype) and in 1963 (H3N8 subtype)4. The H7N7 EIV subtype is considered to be extinct since 19805 and H3N8 subtype continues to cause outbreaks worldwide.

    The techniques HA - hemagglutination assay, HI - inhibition of hemagglutination assay and virus isolation in embryonated chicken eggs, are deeply used to study EIV outbreaks6.With the advance of molecular techniques, globalization and the high visibility of journals/articles/communications, the epidemiology of EIV started to be more deeply studied.

    Initially, the EIVs H3N8 subtypes were defined in a single phylogenetic group7 that evolved into two lineages, American and Eurasian, according to the geographic region8. The American lineage diverged into South America, Kentucky and Florida sub-lineages9. The strains from the Florida sub-lineage suffered two mutations in the hemagglutinin and diverged into Florida Clade 1 (FC1) and Clade 2 (FC2)9,10 represented by the strains A/equine/South Africa/4/03 and A/equine/Newmarket/5/03, respectively11. The FC1 and FC2 strains are responsible for the EIV outbreaks that occurred worldwide in the last years and are the predominant EIVs12,13,14,15,16,17,18,19,20,21.

    In South America, EIV outbreaks caused by the H3N8 subtype were described in Brazil in 1963, 1969, 1985, 1988, 2001, 2012 and 201516,21,22,23,24,25,26,27,28, in Chile in 1963, 1985, 1992, 2006 and 201229,30,31, in Argentina in 2001 and 2012 30,32 and Uruguay in 2012 30. The H3N8 EIVs that were sequenced were more identical to the North American strains than to the European EIVs16, 21, 28, 30, 33.

    In 2012, outbreaks occurred in the United States, Argentina, Brazil, Uruguay and Dubai. The strains had high nucleotide identity and belonged to FC116, 19, 21, 30. According to Perglione et al (2016), the outbreak might have initiated in South America and went to Dubai. Brazil has reported 129 confirmed EIV outbreaks to the OIE in 2012 (World Animal Health Information Database (WAHID) Interface:].

    An outbreak occurred in Brazil in 2015 in a veterinary hospital in the city of São Paulo (State of São Paulo) and different variants were found suggesting the evolution the virus suffered during the same outbreak28.

    Before 2012, only a few studies about the circulating EIVs in South America were described. The surveillance studies of EIV in South America provide information about which strains are causing the outbreaks and control/prevention actions that might be applied such as the use of epidemiologically relevant strains in EIV vaccination11.


    1.Morens D M, Taubenberger J K. (2010) Historical thoughts on influenza viral ecosystems, or behold a pale horse, dead dogs, failing fowl, and sick swine.Influenza OtherRespiViruses.4(6):. 327-337.
    2.Shope R E. (1931) Swine influenza - Filtration experiments and etiology.J Exp Med. 373-385.
    3.Smith W, Andrewes C H, Laidlaw P P. (1933) A virus obtained from influenza patients.Lancet. 222(5732), 66-68.
    4.Waddel G H, Teigland M B, Sigel M M. (1963) A new influenza virus associated with equine respiratory disease.J Am Vet Med Assoc. 143, 587-590.
    5.Webster R G. (1993) Are equine 1 influenza viruses still present in horses?Equine. , Vet J 25(6), 537-538.
    6. (2016) . OIE. WORLD ORGANISATION FOR ANIMAL HEALTH.Terr Man - EquineInflu.Accessed:September11,2017(cap.2.5.7.): 1-16.
    7.Kawaoka Y, Bean W J, Webster R G. (1989) Evolution of the hemagglutinin of equine H3 influenza viruses.Virology. 169(2), 283-292.
    8.Daly J M, ACK Lai, Binns M M, Chambers T M, Barrandeguy M et al. (1996) Antigenic and genetic evolution of equine H3N8 influenza A viruses.J GenVirol. 77(4), 661-671.
    9.ACK Lai, Chambers T M, Holland R E, Morley P S, Haines D M. (2001) Diverged evolution of recent equine-2 influenza (H3N8) viruses in the Western Hemisphere.ArchVirol. 146(6), 1063-1074.
    10.Bryant N A, Rash A S, Russell C A, Cooke A, Bowman S. (2009) Antigenic and genetic variations in European and North American equine influenza virus strains (H3N8) isolated from2006to2007.Vet Microbiol;138(1-2):. 41-52.
    11. (2017) OIE. WORLD ORGANISATION FOR ANIMAL HEALTH. Expert surveillance panel on equine influenza vaccines - conclusions and recommendations.National Institute for Medical Research.,2017
    12.Bryant N A, Rash A S, Woodward A L, Medcalf E, Helwegen M. (2011) Isolation and characterisation of equine influenza viruses. (H3N8) from Europe and North America from2008to2009.Vet Microbiol;147(1-2);19 - 27.
    13.Virmani N, Bera B C, Shanumugasundaram K, Singh B K, Gulati B. (2011) Genetic analysis of the matrix and non-structural genes of equine influenza virus (H3N8) from epizootic of 2008–2009 in India.Vet Microbiol. 152, 169-175.
    14.Bera B C, Virmani N, Shanmugasundaram K, Vaid R K, Sigh B K. (2013) Genetic analysis of the neuraminidase (NA) gene of equine influenza virus (H3N8) from epizootic of 2008-2009 in India.Indian JVirol. 24(2), 256-264.
    15.Gildea S, Fitzpatrick D A, Cullinane A. (2013) Epidemiological and virological investigations of equine influenza outbreaks. in Ireland (2010-2012).Influenza Other Respi Viruses;7(suppl.4): 61-72.
    16.EMC Villalobos, Mori E, MCCSH Lara, AFC Nassar, PRC Braga. (2013) Isolation, sequencing and phylogenetic analysis of equine influenza virus causing the 2012 outbreak. in São Paulo,Brazil.Virus Reviews and Research. In:XXIV Brazilian Congress of Virology, VIIIEncontrodeVirologiaDoMercosul. Vol 18.Porto Seguro,Bahia,Brazil.246 .
    17.Yondon M, Heil G L, Burks J P, Zayat B, Waltzek T B. (2013) Isolation and characterization of H3N8 equine influenza A virus associated with the 2011 epizootic in Mongolia.Influenza OtherRespiViruses. 7(5), 659-665.
    18.Karamendin K, Kydyrmanov A, Kasymbekov Y, Khan E, Daulbayeva K. (2014) Continuing evolution of equine influenza virus in Central Asia,2007-2012.ArchVirol. 159(9), 2321-2327.
    19.Woodward A L, Rash A S, Blinman D, Bowman S, Chambers T M. (2014) Development of a surveillance scheme for equine influenza in the UK and characterisation of viruses isolated. in Europe, Dubai and the USA from 2010-2012.Vet Microbiol;169(3-4): 113-127.
    20.Legrand L J, PHY Pitel, Cullinane A A, Fortier G D, Pronost S L. (2015) Genetic evolution of equine influenza strains isolated in France from2005to2010.Equine VetJ;47(2):. 207-211.
    21.Beuttemmüller E A, Woodward A, Rash A, LES Ferraz, Alfieri A F. (2016) Characterisation of the epidemic strain of H3N8 equine influenza virus responsible for outbreaks in South America in 2012.VirolJ. 13(1), 45.
    22.Andrews C, Pereira H G.. Wildy P (1978)Viruses of Vertebrates. 4th ed , London, United Kingdom: Balliére Tindall .
    23.Cunha R G. (1970) Isolamento do vírus de influenza A/equi 2noEstadodaGuanabara.Rev Bras Biol;. 30(4), 491-498.
    24.Pereira H G, Takimoto S, Piegas N S, do Valle LA. (1972) Antigenic variation of equine (Heq2Neq2) influenzavirus.Bull World Health Organ. 47(4), 465-469.
    25.Cunha R G, Passos W S, MCC Pagano, Souza D M. (1986) Surto de gripe equina produzido por vírus de influenza A/equi 2 no Estado do Rio de Janeiro, Brasil.Rev Bras Med Veterinária. 8(3), 88-91.
    26.DAP Mancini, Geraldes E A, Pinto J R, Soares M A. (1988) Ocorrência de influenza equina na fazenda São Joaquim, São Roque. SP, do Instituto Butantan.Rev da Fac Med Veterinária e Zootec da Univ São Paulo 25(1), 93-100.
    27.Loureiro B O. (2004) Estudo de um surto de influenza eqüina ocorrido em2001no Estado do Rio de Janeiro mediante a caracterização do vírus e avaliação do esquema vacinal.
    28.Favaro P F, Fernandes W R, Reischak D, Brandão P E, SOS Silva. (2018) Evolution of equine influenza viruses (H3N8) during a Brazilian outbreak . , 2015.Brazilian J Microbiol 49(2), 336-346.
    29.Müller I, Pinto E, Santibáñez M C, Celedón M O.. Valenzuela PD.(2009) Isolation and characterization of the equine influenza virus causing the 2006 outbreak in Chile.Vet Microbiol;137(1-2): 172-177.
    30.Perglione C O, Gildea S, Rimondi A, Miño A, Vissani A. (2016) Epidemiological and virological findings during multiple outbreaks of equine influenza in South America in 2012.Influenza OtherRespiViruses. 10(1), 37-46.
    31.Berríos P E.Influenza equina en Chile(1963-1992).(2005) Un posible caso en un ser humano.RevChilinfectología. 22(1), 47-50.
    32.Sguazza G H, Fuentealba N A, Tizzano M A, Galosi C M, Pecoraro M R. (2009) Complete genome amplification of equine influenza virus subtype 2.Rev Argent Microbiol. 41, 207-211.
    33.Müller I, Jaureguiberry B, PDT Valenzuela. (2005) Isolation, sequencing and phylogenetic analysis of the hemagglutinin, neuraminidase and nucleoprotein genes of the Chilean equine influenza virus subtypes H7N7 and H3N8.Biol Res. 38(1), 55-67.