Abstract
Background: The emergence of human infection with avian influenza A(H7N9) virus was reported in Wenshan City, southwestern China in 2017. The study describes the epidemiological and virological features of the outbreak and discusses the origin of the infection. Methods: Poultry exposure and timelines of key events for each patient were collected. Samples derived from the patients, their close contacts, and environments were tested for influenza A(H7N9) virus by real-time reverse transcription polymerase chain reaction. Genetic sequencing and phylogenetic analysis were also conducted. Results: Five patients were reported in the outbreak. An epidemiological investigation showed that all patients had been exposed at live poultry markets. Virus isolates from these patients had low pathogenicity in avian species. Both epidemiological investigations of chicken sources and phylogenetic analysis of viral gene sequences indicated that the source of infection was from Guangxi Province. Conclusions: The transmission route spanned a long geographical region, with virus spreading from east to west. Chickens were an important carrier in the H7N9 virus spreading from Guangxi to Wenshan. Hygienic management of live poultry markets and virological screening of chickens transported across regions should be reinforced to limit the spread of H7N9 virus.
Spatial and temporal analysis of human infection with the avian influenza A (H7N9) virus in China and research on risk assessment agent-based model
