Abstract:

【Objective】 This study engaged in epidemiological surveillance of low pathogenic avian influenza A viruses in poultry in Eastern China. 【Method】 From July 2002 to September 2009, 11 645 cloacal swab samples were collected from poultry in the LPMs (live–poultry markets), which were from different provinces. All cloacal swabs were tested for hemagglutinating viruses by inoculating embryonated hens eggs. 【Result】 There were 1 158 strains of AIVs were isolated with an isolation rate of 9.94%. These strains of AIV belonged to eight HA subtypes, the isolation rate of high to low were H3, H6, H11, H1, H4, H9, H10, and H8. 【Conclusion】The isolation rate of AIVs was distributed with significant seasonal variations, higher in winter and spring and lower in summer. The distribution of HA subtypes of AIVs was also uneven in different months. So far, eight HA subtypes (H1, H3, H4, H6, H8, H9, H10 and H11) and seven NA subtypes (N1, N2, N3, N4 , N5, N6 and N8) were isolated from domestic ducks. Strains in HA and NA subtypes combination included the following 17 subtypes. Domestic duck is still the most prone to mixed infections, and since 2007 H6 subtypes have played an important role that are able to mix infect poultry with H3, H11, H4, H9 subtype etc, providing a good vector to generate new subtypes and variation of virulence.

Key words: LPAI, epidemiology, poultry