Virological and serological study of human infection with swine influenza A H1N1 virus in China

Background: Pigs are considered to be mixing vessels for the emergence of influenza viruses with pandemic potential. 2009 Pandemic Influenza H1N1 further proved this hypothesis, and raised the needs for risk assessment of human cases caused by swine influenza virus. Methods: A field investigation was conducted after a case identified with infection of European avian-like swine influenza H1N1 virus. The diagnosis was confirmed by real-time PCR, virus isolation, whole genome sequencing and serological assays. Samples from local pigs and close contacts were tested to identify the source of infection and route of transmission. Results: The virus from the index case was similar to viruses circulating in the local pigs. The case's grandfather was asymptomatic with sero-conversion. A total of 42.8% of swine sera were positive for European avian-like swine H1N1. Conclusions: This study highlighted the importance of performing surveillance on swine influenza to monitor new virus emergence in humans. (C) 2013 Elsevier Inc. All rights reserved.