• Open Access

Serologic evidence of human influenza virus infections in swine populations, Cambodia

Authors

  • Sareth Rith,

    1. Institut Pasteur in Cambodia, Virology Unit, Réseau International des Instituts Pasteur, Phnom Penh, Cambodia.
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    • These authors contributed equally.

  • Punnaporn Netrabukkana,

    1. School of Veterinary and Biomedical Sciences, Division of Health Sciences, Murdoch University, Murdoch, WA, Australia.
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    • These authors contributed equally.

  • San Sorn,

    1. National Veterinary Research Institute, Department of Animal Health Production, Ministry of Agriculture Forestry and Fisheries, Phnom Penh, Cambodia.
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  • Elizabeth Mumford,

    1. World Health Organization, Global Influenza Programme, Geneva, Switzerland.
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  • Channa Mey,

    1. Institut Pasteur in Cambodia, Virology Unit, Réseau International des Instituts Pasteur, Phnom Penh, Cambodia.
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  • Davun Holl,

    1. School of Veterinary and Biomedical Sciences, Division of Health Sciences, Murdoch University, Murdoch, WA, Australia.
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  • Flavie Goutard,

    1. Institut Pasteur in Cambodia, Virology Unit, Réseau International des Instituts Pasteur, Phnom Penh, Cambodia.
    2. French Agricultural Research Center for International Development (CIRAD), Animal and Integrated Risk Management Research Unit (AGIRs), Montpellier, France.
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  • Bunthin Y,

    1. Institut Pasteur in Cambodia, Virology Unit, Réseau International des Instituts Pasteur, Phnom Penh, Cambodia.
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  • Stan Fenwick,

    1. School of Veterinary and Biomedical Sciences, Division of Health Sciences, Murdoch University, Murdoch, WA, Australia.
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  • Ian Robertson,

    1. School of Veterinary and Biomedical Sciences, Division of Health Sciences, Murdoch University, Murdoch, WA, Australia.
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  • François Roger,

    1. French Agricultural Research Center for International Development (CIRAD), Animal and Integrated Risk Management Research Unit (AGIRs), Montpellier, France.
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  • Philippe Buchy

    1. Institut Pasteur in Cambodia, Virology Unit, Réseau International des Instituts Pasteur, Phnom Penh, Cambodia.
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Philippe Buchy, Virology Unit, Institut Pasteur in Cambodia, Réseau International des Instituts Pasteur, 5 Monivong blvd, PO box 983, Phnom Penh, Cambodia. E-mail: pbuchy@pasteur-kh.org

Abstract

Background  This study was conducted from 2006 to 2010 and investigated the seroprevalence of influenza A viruses in Cambodian pigs, including human H1N1, H3N2, 2009 pandemic H1N1 (A(H1N1)pdm09), and highly pathogenic avian H5N1 influenza A viruses.

Methods  A total of 1147 sera obtained from pigs in Cambodia were tested by haemagglutination inhibition (HI) assays for antibody to human influenza A viruses along with both HI and microneutralization (MN) tests to assess immunological responses to H5N1 virus. The results were compared by year, age, and province.

Results  Antibodies against a human influenza A virus were detected in 14·9% of samples. A(H1N1)pdm09 virus were dominant over the study period (23·1%), followed by those to human H1N1 (17·3%) and H3N2 subtypes (9·9%). No pigs were serologically positive for avian H5 influenza viruses. The seroprevalence of human H1N1 and H3N2 influenza viruses peaked in 2008, while that of A(H1N1)pdm09 reached a peak in 2010. No significant differences in seroprevalence to human influenza subtypes were observed in different age groups.

Conclusions  Cambodian pigs were exposed to human strains of influenza A viruses either prior to or during this study. The implications of these high prevalence rates imply human-to-swine influenza virus transmission in Cambodia. Although pigs are mostly raised in small non-commercial farms, our preliminary results provide evidence of sustained human influenza virus circulation in pig populations in Cambodia.

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