Wild birds are believed to be the reservoir of influenza A viruses, and poultry may serve as a key intermediate in the cross-species avian influenza virus (AIV) transmission from wild birds to human. Backyard poultry, especially those located in the flyway of migratory birds, is thought to play a vital role in the introduction of wild bird AIVs, according to an announcement from Science China Press.

A novel reassortant AIV, influenza A(H7N4), has been identified in such a scenario, according to a new study published by Science Bulletin, the announcement said.

Based on epidemiological and laboratory investigations conducted at the Jiangsu Provincial Center for Disease Control & Prevention in Nanjing, China, and other institutions in China, the novel H7N4 virus originated from wild bird AIVs, infected backyard chickens and ducks and caused a severe human infection, the announcement said.

A comprehensive investigation has been conducted on this case, confirming the viral infection and the transmission route. Early identification and response to this incident interrupted the spread of this novel virus.

"Threats from AIVs never stop. For early warning and preparedness regarding influenza pandemic, it is important to keep alert on the AIV infection of backyard poultry and feeders," the authors said.

Based on the genome sequencing, the accountable novel virus is distinct from previously reported avian H7N4 and H7N9 viruses, the announcement said. It is low pathogenic to avian species, susceptible to antivirals and has binding preference of avian-like alpha-2, 3-linked sialic acid receptor.

More information on the findings can be found in the following links:

* Huo Xiang, Cui Lun-biao, Chen Cong et al. Severe human infection with a novel avian-origin influenza A(H7N4) virus. Sci Bull, 2018, 63:1043-1050

* Yuen KY. Another avian influenza A subtype jumping into human: this time is H7N4. Sci Bull, 2018, 63:1025-1026.