Researchers have suggested that among the copious species of poultry in China, quail and chickens are the likely sources of infection of H7N9 influenza virus to humans
The H7N9 avian influenza virus was first reported in humans in March 2013 in China. Since then over 375 human cases have been confirmed and over 100 have died.
Only 1 case has been reported outside of China: A woman from Guangdong Province who was traveling in Malaysia and is presumed to have contracted the virus in China. According to the World Health Organization, most known human infections have resulted from direct or indirect contact with poultry.
Corresponding author David Suarez, of the United States Department of Agriculture, laboratory originally became concerned about H7N9 after sequences from several isolates were made available in public databases, early in the outbreak.
In the study, Suarez and his collaborators first infected seven species of poultry with a human isolate of the Chinese H7N9 virus. The virus replicated well in quail and chickens, and the former quickly infected their cage-mates, says Suarez.
The virus replicated less well in other poultry species, and did not transmit efficiently. Pigeons were notably resistant to becoming infected. In additional experiments, quail transmitted virus efficiently, while pekin ducks and pigeons did not.
None of the poultry species became sick when infected with H7N9, making detection of the virus that much more difficult in the birds, says Suarez.
The study has been published in the Journal of Virology.