Possible role of songbirds and parakeets in transmission of influenza A(H7N9) virus to humans

Abstract

Avian-origin influenza A(H7N9) recently emerged in China, causing severe human disease. Several subtype H7N9 isolates contain influenza genes previously identified in viruses from finch-like birds. Because wild and domestic songbirds interact with humans and poultry, we investigated the susceptibility and transmissibility of subtype H7N9 in these species. Finches, sparrows, and parakeets supported replication of a human subtype H7N9 isolate, shed high titers through the oropharyngeal route, and showed few disease signs. Virus was shed into water troughs, and several contact animals seroconverted, although they shed little virus. Our study demonstrates that a human isolate can replicate in and be shed by such songbirds and parakeets into their environment. This finding has implications for these birds' potential as intermediate hosts with the ability to facilitate transmission and dissemination of A(H7N9) virus.

Keywords: China; Passeriformes; Psittaciformes; budgerigar; finch; host intermediate; influenza virus H7N9; influenza virus avian; influenza virus human; parakeets; songbird; sparrow; transmission; zoonoses.

Figure

Virus shedding into water trough. A 500-μL sample of water was collected daily for 6 days, and virus was titrated in chicken eggs. The lower limit of detection was 0.75 50% egg infectious dose/mL.