Humans ; Influenza A Virus, H1N1 Subtype ; Influenza, Human ; epidemiology ; virology

Humans ; Influenza A Virus, H1N1 Subtype ; Influenza, Human ; epidemiology ; virology

Humans ; Influenza A Virus, H1N1 Subtype ; Influenza, Human ; epidemiology ; virology

From February 2013, a novel avian influenza A H7N9 virus causing human infection with fatal outcomes has been identified in eastern China. This avian influenza A H7N9 virus is a triple reassortant of viruses that are avian-origin only and it is low pathogenic in poultry. Several characteristic amino acid mutations in HA and PB2 polymerase subunit (including G186V, Q226L and E627K substitution) have been found through sequence analysis, and these mutations probably facilitate binding to human-type receptors and efficient replication in mammals. Other mutations in NA, M2 and NS genes were also found. Although sustained human-to-human transmission has not been conclusively established, limited human-to-human transmission of the H7N9 virus remains possible. Intensified surveillance for the H7N9 virus in humans and animals is needed to answer questions about the viral origin, spread and potential threat.
Animals ; Birds ; virology ; China ; epidemiology ; Humans ; Influenza A virus ; genetics ; Influenza in Birds ; virology ; Influenza, Human ; transmission ; virology ; Mutation

Animals ; Birds ; China ; Humans ; Influenza A Virus, H7N9 Subtype ; pathogenicity ; Influenza in Birds ; epidemiology ; virology ; Influenza, Human ; epidemiology ; virology

Humans ; Influenza A virus ; Influenza Vaccines ; Influenza, Human ; epidemiology ; prevention & control ; virology

China ; epidemiology ; Humans ; Influenza A Virus, H7N9 Subtype ; pathogenicity ; Influenza, Human ; epidemiology ; virology

Child ; China ; epidemiology ; Female ; Humans ; Influenza A Virus, H7N9 Subtype ; Influenza, Human ; epidemiology ; virology

Aged, 80 and over ; China ; epidemiology ; Communicable Diseases ; epidemiology ; virology ; Female ; Humans ; Influenza A Virus, H7N9 Subtype ; Influenza, Human ; epidemiology ; virology

Wild birds (mainly Anseriformes and Charadriiformes) are recognized as the natural reservoir of avian influenza viruses (AIVs). The long-term surveillance of AIVs in wild birds has been conducted in North America and Europe since 1970s. More and more surveillance data revealed that all the HA and NA subtypes of AIVs were identified in the wild ducks, shorebirds, and gulls, and the AIVs circulating in wild birds were implicated in the outbreaks of AIVs in poultry and humans. Therefore, the AIVs in wild birds pose huge threat to poultry industry and human health. To gain a better understanding of the ecology and epidemiology of AIVs in wild birds, we summarize the transmission of AIVs between wild birds, poultry, and humans, the main results of surveillance of AIVs in wild birds worldwide and methods for surveillance, and the types of samples and detection methods for AIVs in wild birds, which would be vital for the effective control of avian influenza and response to possible influenza pandemic.
Animals ; Animals, Wild ; virology ; Birds ; virology ; Humans ; Influenza A virus ; genetics ; isolation & purification ; physiology ; Influenza in Birds ; epidemiology ; transmission ; virology ; Influenza, Human ; epidemiology ; transmission ; virology ; Sentinel Surveillance ; veterinary