Background: The recent avian influenza epidemic in Asia and the H1N1 pandemic demonstrated that influenza A viruses pose a threat to global public health. The animal origins of the viruses confirmed the potential for interspecies transmission. Swine are hypothesized to be prime "mixing vessels" due to the dual receptivity of their trachea to human and avian strains. Additionally, avian and human influenza viruses have previously been isolated in swine. Therefore, understanding interspecies contact on smallholder swine farms and its potential role in the transmission of pathogens such as influenza virus is very important.Methods: This qualitative study aimed to determine swine-associated interspecies contacts in two coastal areas of Peru. Direct observations were conducted at both small-scale confined and low-investment swine farms (n = 36) and in open areas where swine freely range during the day (n = 4). Interviews were also conducted with key stakeholders in swine farming.Results: In both locations, the intermingling of swine and domestic birds was common. An unexpected contact with avian species was that swine were fed poultry mortality in 6/20 of the farms in Chancay. Human-swine contacts were common, with a higher frequency on the confined farms. Mixed farming of swine with chickens or ducks was observed in 36% of all farms. Human-avian interactions were less frequent overall. Use of adequate biosecurity and hygiene practices by farmers was suboptimal at both locations.Conclusions: Close human-animal interaction, frequent interspecies contacts and suboptimal biosecurity and hygiene practices pose significant risks of interspecies influenza virus transmission. Farmers in small-scale swine production systems constitute a high-risk population and need to be recognized as key in preventing interspecies pathogen transfer. A two-pronged prevention approach, which offers educational activities for swine farmers about sound hygiene and biosecurity practices and guidelines and education for poultry farmers about alternative approaches for processing poultry mortality, is recommended. Virological and serological surveillance for influenza viruses will also be critical for these human and animal populations.
Bibliographical noteFunding Information:
Thank you to all of the study participants for allowing us to observe their daily lives and for sharing their opinions on swine farming in Peru. Thanks also to Juana Veramendi and Maria Alvarez, who were instrumental in locating participants and assisting with fieldwork. The authors are especially grateful to Dr. Elli Leontsini and Gabrielle Hunter of John Hopkins University for their valuable input on swine farming. Fieldwork in Tumbes was supported in part by funding from the Bill and Melinda Gates Foundation (23981), the NIH/NSF “Ecology and Evolution of Infectious Diseases” award from the Fogarty International Center at the U.S. National Institutes of Health (3R01-TW005869), and a Training grant from the Fogarty International Center (D43-TW001140)002E 1Asociación Benéfica Proyectos en Informática, Salud, Medicina y Agricultura (AB PRISMA), Lima, Peru. 2Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima, Peru. 3Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. 4Facultad de Salud Pública y Administración, Universidad Peruana Cayetano Heredia, Lima, Peru. 5Center for Global Health, Universidad Peruana Cayetano Heredia, Tumbes, Peru. 6Centers for Disease Control and Prevention, Atlanta, GA, USA. 7Naval Medical Research Unit - 6, Lima, Peru. 8Division of Infectious Diseases, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.