Table 1

Isolation of AIV from duck farms in Dongting Lake region of Hunan Province, China, between winter 2011 and spring 2012

Sampling timeNo. of duck farms sampledTotal no. of samples from ducksTotal no. of samples from duck farm environmentNo. of influenza virus isolates of HA subtypeNo. of viruses isolated from:Total no. of viruses
Winter 2011541,62054020430209117421
Spring 2012471,4104702166202021609019109