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. 2016 Jan;10(1):47-56.
doi: 10.1111/irv.12329.

Transmission dynamics of pandemic influenza A(H1N1)pdm09 virus in humans and swine in backyard farms in Tumbes, Peru

Yeny O Tinoco  1   2 , Joel M Montgomery  1   3 , Mathew R Kasper  1 , Martha I Nelson  4 , Hugo Razuri  1 , Maria C Guezala  1 , Eduardo Azziz-Baumgartner  5 , Marc-Alain Widdowson  5 , John Barnes  5 , Robert H Gilman  2 , Daniel G Bausch  1   6 , Armando E Gonzalez  7
Affiliations

Transmission dynamics of pandemic influenza A(H1N1)pdm09 virus in humans and swine in backyard farms in Tumbes, Peru

Yeny O Tinoco et al. Influenza Other Respir Viruses. 2016 Jan.

Abstract

Objectives: We aimed to determine the frequency of pH1N1 transmission between humans and swine on backyard farms in Tumbes, Peru.

Design: Two-year serial cross-sectional study comprising four sampling periods: March 2009 (pre-pandemic), October 2009 (peak of the pandemic in Peru), April 2010 (1st post-pandemic period), and October 2011 (2nd post-pandemic period).

Sample: Backyard swine serum, tracheal swabs, and lung sample were collected during each sampling period.

Main outcome measures: We assessed current and past pH1N1 infection in swine through serological testing, virus culture, and RT-PCR and compared the results with human incidence data from a population-based active surveillance cohort study in Peru.

Results: Among 1303 swine sampled, the antibody prevalence to pH1N1 was 0% pre-pandemic, 8% at the peak of the human pandemic (October 2009), and 24% in April 2010 and 1% in October 2011 (post-pandemic sampling periods). Trends in swine seropositivity paralleled those seen in humans in Tumbes. The pH1N1 virus was isolated from three pigs during the peak of the pandemic. Phylogenetic analysis revealed that these viruses likely represent two separate human-to-swine transmission events in backyard farm settings.

Conclusions: Our findings suggest that human-to-swine pH1N1 transmission occurred during the pandemic among backyard farms in Peru, emphasizing the importance of interspecies transmission in backyard pig populations. Continued surveillance for influenza viruses in backyard farms is warranted.

Keywords: Antibodies; backyard pig farms; human-animal transmission; influenza.

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Figures

Figure 1
Figure 1
(A) Map of South America showing the study site region (indicated by a cross) and the geographic provenance of the three viruses (indicated by stars) which clustered most closely on phylogenetic analysis with the viruses obtained from swine in Tumbes. (B) Map of the Tumbes region, Peru, showing sites of backyard farms with pigs positive for antibody to influenza A(H1N1)pdm09 virus during the peak pandemic period (black circles), the 1st post‐pandemic period (blue circles), and during the 2nd post‐pandemic pandemic period (red circles).
Figure 2
Figure 2
Antibody prevalence and isolation of influenza A(H1N1)pdm09 virus (pH1N1) from sera and tracheal swabs of backyard pigs collected in Tumbes, Peru, 2009–2011. The dates of the four sampling periods are circled on the x‐axis. The incidence of pH1N1 influenza in humans in Tumbes is shown in gray, obtained from surveillance through an influenza cohort study conducted by our research team which began on July 27, 2009.24 There was no evidence of pH1N1 influenza activity during November 2010 to September 2011. The first case of pH1N1 influenza in humans in Tumbes was reported by the Peruvian Ministry of Health on July 1, 2009.
Figure 3
Figure 3
Maximum‐likelihood phylogeny of concatenated hemagglutinin and neuraminidase gene sequences from influenza A(H1N1)pdm09 viruses from Latin America, 2009–2011. Virus sequences shown were collected from three swine (orange with circles) and two humans in Tumbes (blue with circles) (see explanation in text), 13 swine in Argentina and Brazil (green), 14 humans in other sites in Peru (blue), 132 humans in other Latin American countries (black), and the red line: Influenza A/California/07/2009. Bootstrap values >70 are included for key nodes, and tree is midpoint rooted for clarity only. GenBank accession numbers of the sequences used in this analysis are listed in Appendix 2.
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References

    1. Nelson MI, Gramer MR, Vincent AL, Holmes EC. Global transmission of influenza viruses from humans to swine. J Gen Virol 2012; 93(Pt 10):2195–2203. - PMC - PubMed
    1. Vijaykrishna D, Smith GJ, Pybus OG et al Long‐term evolution and transmission dynamics of swine influenza A virus. Nature 2011; 473:519–522. - PubMed
    1. Dawood FS, Jain S, Finelli L et al Emergence of a novel swine‐origin influenza A (H1N1) virus in humans. N Engl J Med 2009; 360:2605–2615. - PubMed
    1. Pasma T, Joseph T. Pandemic (H1N1) 2009 infection in swine herds, Manitoba, Canada. Emerg Infect Dis 2010; 16:706–708. - PMC - PubMed
    1. Trevennec K, Leger L, Lyazrhi F et al Transmission of pandemic influenza H1N1 (2009) in Vietnamese swine in 2009–2010. Influenza Other Respir Viruses 2012; 6:348–357. - PMC - PubMed

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