The current H5N1 strain is a fast-mutating, highly pathogenic avian influenza virus (HPAI) found in multiple bird species.

In January 2005 an outbreak of avian influenza affected thirty three out of sixty four cities and provinces in Vietnam, leading to the forced killing of nearly 1.2 million poultry.

In April 2005 an unprecedented die-off began of over 6,000 migratory birds at Qinghai Lake in central China over three months.

David Nabarro later stated that as the virus had spread to migratory birds, an outbreak could start in Africa or the Middle East.

That brings the death toll [...] to 74, comprising 14 victims in Thailand, four in Cambodia, 11 in Indonesia, 42 in Vietnam and three in China.