A study of the relationship between human infection with avian influenza a (H5N6) and environmental avian influenza viruses in Fujian, China

Abstract Background Avian influenza A (H5N6) virus poses a great threat to the human health since it is capable to cross the species barrier and infect humans. Although human infections are believed to largely originate from poultry contaminations, the transmissibility is unclear and only limited information was available on poultry environment contaminations, especially in Fujian Province. Methods A total of 4901 environmental samples were collected and tested for Avian Influenza Virus (AIV) from six cities in Fujian Province through the Fujian Influenza Surveillance System from 2013 to 2017. Two patient-related samples were taken from Fujian’s first confirmed H5N6 human case and his backyard chicken feces in 2017. Chi-square test or Fisher’s exact probability test was used to compare the AIV and the viral subtype positive rates among samples from different Surveillance cities, surveillance sites, sample types, and seasons. Phylogenetic tree analysis and molecular analysis were conducted to track the viral transmission route of the human infection and to map out the evolutions of H5N6 in Fujian. Results The overall positive rate of the H5 subtype AIVs was 4.24% (208/4903). There were distinctive differences (p