Live animal markets in Minnesota: A potential source for emergence of novel influenza a viruses and interspecies transmission

Mary J. Choi, Montserrat Torremorell, Jeff B. Bender, Kirk Smith, David Boxrud, Jon R. Ertl, My Yang, Kamol Suwannakarn, Duachi Her, Jennifer Nguyen, Timothy M. Uyeki, Min Levine, Stephen Lindstrom, Jacqueline M. Katz, Michael Jhung, Sara Vetter, Karen K. Wong, Srinand Sreevatsan, Ruth Lynfield

Research output: Contribution to journalArticlepeer-review


Background.Live animal markets have been implicated in transmission of influenza A viruses (IAVs) from animals to people. We sought to characterize IAVs at 2 live animal markets in Minnesota to assess potential routes of occupational exposure and risk for interspecies transmission. Methods.We implemented surveillance for IAVs among employees, swine, and environment (air and surfaces) during a 12-week period (October 2012-January 2013) at 2 markets epidemiologically associated with persons with swine-origin IAV (variant) infections. Real-time reverse transcription polymerase chain reaction (rRT-PCR), viral culture, and whole-genome sequencing were performed on respiratory and environmental specimens, and serology on sera from employees at beginning and end of surveillance. Results.Nasal swabs from 11 of 17 (65%) employees tested positive for IAVs by rRT-PCR; 7 employees tested positive on multiple occasions and 1 employee reported influenza-like illness. Eleven of 15 (73%) employees had baseline hemagglutination inhibition antibody titers ≥40 to swine-origin IAVs, but only 1 demonstrated a 4-fold titer increase to both swine-origin and pandemic A/Mexico/4108/2009 IAVs. IAVs were isolated from swine (72/84), air (30/45), and pen railings (5/21). Whole-genome sequencing of 122 IAVs isolated from swine and environmental specimens revealed multiple strains and subtype codetections. Multiple gene segment exchanges among and within subtypes were observed, resulting in new genetic constellations and reassortant viruses. Genetic sequence similarities of 99%-100% among IAVs of 1 market customer and swine indicated interspecies transmission. Conclusions.At markets where swine and persons are in close contact, swine-origin IAVs are prevalent and potentially provide conditions for novel IAV emergence.

Original languageEnglish (US)
Pages (from-to)1355-1362
Number of pages8
JournalClinical Infectious Diseases
Issue number9
StatePublished - Nov 1 2015

Bibliographical note

Publisher Copyright:
© The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America.


  • human
  • influenza
  • live animal markets
  • swine


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