* 21 May 1997: Lethal flu virus H5N1 isolated from human patient in Hong Kong. Six people in close contact with poultry die. Hong Kong's chicken population culled.
* February 2003: Virus kills person in Hong Kong.
* December 2003: South Korea's first outbreak.
* January 2004: Outbreaks in China and Japan; eight die in Thailand and Vietnam. WHO starts developing vaccine candidates in US and UK.
* March 2004: Virus widespread among bird flocks in Asia. More human deaths in Vietnam and Thailand.
* August 2004: 100 million chickens culled. Chinese report avian flu in pigs.
* Nov 2004: WHO warns of pandemic that could kill millions of people, and "much of the world is unprepared".
* December 2004: Year's death toll is 32.
* February 2005: 12 more deaths in Vietnam; flu spreads to Cambodia.
* May 2005: WHO reports 53 deaths in Vietnam, Cambodia and Thailand since January 2004.
* October 2005: Cases in Romania, Turkey, Greece and Russia. Mass culling. * 16 October 2005: Sir Liam Donaldson, chief medical officer, says deadly outbreak of avian flu would come when strain mutated with human flu. It would probably kill 50,000 in the UK, but epicentre likely to be East Asia.
* 17 October 2005: Greece reports first case in poultry.