Seroepidemiological Survey Of Aiv Of H5 And H7 Ha Subtypes Among Domestic Ducks In Xiangxi

To understand the rate, the scope and the time of H5 and H7 AIV infection in domestic duck raised in sporadic field in Xiangxi region, hemagglutination inhibition assay was conducted on 159 serum specimens collected seasonly from nonimmune ducks in Xiangxi by using inactivated H5 and H7 AIV as detective antigens respectively. The results showed 20.75%(198/954) and 3.17%(36/954) antibody positive rate against H5 and H7 AIV respectively, which indicated the prevalence of H5 AIV was much higher in nonimmune ducks, and the highest infection rate occurred in winter.To further determine the immune state and the potential infection of HPAI in large scaled duck herd, different aged ducks immunized with inactivated H5 AIV vaccine from four herds were tested for H5 and H7 AIV antibody. The results showed H5 AIV antibody qualification rate for four duck herds was 65.56%(59/90),67.78% (61/90),53.33%(48/90),47.78%(43/90) respectively, indicated the antibody level induced by immunization need to be improved to provide full protection against AIV; No antibody against H7 AIV was detected, proved no H7 AIV infection in large scaled duck herds.