Abstract
H5 high pathogenicity avian influenza viruses, which emerged in Guangdong Province, China, in 1996, has now been persistently transmitted among various wild birds due to the "silent spreading" of the viruses among vaccinated poultry and domestic waterfowl. These viruses traveled long distances along with bird migration; therefore, the threat of H5 high pathogenicity avian influenza viruses is now a global issue. Furthermore, infection in wild mammals has become more prominent since 2020. The contamination of the wild bird population by the virus is considered to be an irreversible situation, and thus, the reduction of virus levels in the environment is an urgent issue to prevent further deterioration of the situation. This review will describe the history and current situations of influenza virus infection in wild birds and mammals, and discuss the research and countermeasures that are required to stop the damage caused by this virus.
