Abstract

The brief history and major events of subtypes H9N2 and H5N1 avian influenza in China during 1992-2008 are summarized. For the control of H5N1 HPAI , government-subsidized intensive vaccination program and other control measures including enforced biosecurity of poultry farms, restriction on the movement of poultry and products, culling, quarantine and disinfection has been implemented in China since 2004. In general, these strategies are successful in terms of reducing the number of outbreaks, losses from clinical disease and virus load of poultry in endemic areas. On the other hand, the long term endemicity of H5N1 viruses in poultry populations in China, especially in domestic ducks, constitutes the real threat to public health and agriculture. It has a long way to go for reaching the final goal of H5N1 virus eradication. China produces about two billion domestic ducks each year, almost 75% of world total yield. The author emphasizes the importance that domestic ducks play in the maintenance and evolution of H5N1 avian influenza viruses.