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

Abstract

ObjectivesWe aimed to determine the frequency of pH1N1 transmission between humans and swine on backyard farms in Tumbes, Peru.DesignTwo‐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).SampleBackyard swine serum, tracheal swabs, and lung sample were collected during each sampling period.Main outcome measuresWe 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.ResultsAmong 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.ConclusionsOur 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.

Serological surveillance and factors associated with influenza A virus in backyard pigs in Southern Brazil

“…This result corroborates a previous study performed in Guatemala, where a high percentage of the pandemic H1 was detected in backyard pig farms, but exposure to swine-origin IAVs from other H1 clades was only found in commercial pig farms showed 24% of seropositive pigs in holdings with intensive production system (Almeida et al, 2017). Similarly, a seroprevalence of 1% was found in backyard pig samples collected in post-pandemic period in Peru (Tinoco et al, 2016). The fact that the backyard pig population is usually composed by few animals of different ages that are housed in low density could partially explain the lower prevalence of anti-IAV antibodies observed here.…”

“…Thereby, there are IAV reports in backyard pig populations in North America, Europe, Africa and Asia (Couacy-Hymann et al, 2012;Monger et al, 2014;Osbjer et al, 2017;Weller, Cadmus, Ehrhart, Powers, & Pabilonia, 2013). In Latin America, recent reports showed IAV seroprevalence and evidence of transmission from human into pigs (Bravo-Vasquez et al, 2017;Dibarbora et al, 2017;Gonzalez-Reiche et al, 2017;Tinoco et al, 2016). Information regarding IAV seroprevalence (Almeida et al, 2017) and/or virus characterization from backyard pig population in Brazil is still scarce, and it is unknown which IAV subtypes circulate in these pig populations, as well the risk of inter-species transmission.…”

Novel Human-like Influenza A Viruses Circulate in Swine in Mexico and Chile

“…Since the 2009 H1N1 pandemic, our understanding of the global diversity and evolution of influenza A viruses in swine (IAV-S) has increased. A more complete picture of the genetic diversity of IAV-S circulating globally has been provided by the expansion of IAV-S surveillance in many countries, including Argentina 1 , Australia 2 , Cameroon 3 , Canada 4 , China 5 , Peru 6 , Japan 7 , Mexico 8 , Sri Lanka 9 , Thailand 10 , the United States 11 , Vietnam 12 , and multiple countries in Europe 13 , 14 , 15 . The expansion of surveillance has advanced our understanding of how IAV diversity evolves in swine hosts, including the importance of frequent transmission of IAVs from humans to swine 16 , 17 , reassortment 5 , 11 , 13 , 15 , 18 , 19 , and the role of the live swine trade in disseminating viral diversity between countries and continents 20 , 21 .…”

“…Recently increased IAV-S surveillance in Argentina, Brazil, Colombia, and Mexico has identified multiple IAV-S lineages of human origin, including pandemic and seasonal IAVs as well as reassortants 1 , 6 , 8 , 24 , 25 , 26 , 27 . In Argentina, IAVs of human origin have been identified in swine, including the H1N1, H1N2, and H3N2 subtypes, with evidence of circulation for many years prior to detection 16 , 24 .…”

A Systematic Review Analyzing the Prevalence and Circulation of Influenza Viruses in Swine Population Worldwide

“…The A(H1N1)pdm09 virus antibodies were detected in 110 backyard swine in Peru during March 2009-October 2011. Total four A(H1N1)pdm09 virus isolates were retrieved and sequenced which determined that there were at least two separate events of A(H1N1)pdm09 virus transmission from human to backyard swine in Peru [331].…”