The discovery of bird flu in turkeys at Redgrave Park Farm in Suffolk is the latest episode of the virus now affecting the UK.
In April 2006 a strain was found in chickens at a Norfolk farm and the month before that the deadly H5N1 strain was found in a dead swan on the Fife coast.
Below are the key developments in the UK so far:
10 January 2008 Three mute swans in Dorset are found dead with the virulent H5N1 strain of bird flu.
19 December 2007 All restrictions on bird gatherings and movements of poultry and poultry meat are lifted.
8 December 2007 Bird flu protection measures around the infected farms begin to be lifted.
23 November 2007 The national ban on bird shows and pigeon races, in place since 12 November, is lifted. Restrictions remain within the surveillance and protection zones in Suffolk and Norfolk.
21 November 2007 A further 68,000 birds are slaughtered on a sixth poultry farm in Suffolk in a bid to control the outbreak. The cull is more than double the other five combined.
19 November 2007 A case of the virulent H5N1 strain of bird flu is confirmed at Hill Meadow Farm, in Knettishall, Suffolk. The farm is near to Redgrave Park Farm where the outbreak began on 12 November.
16 November 2007 The outbreak forces organisers to axe the Royal Welsh Winter Fair, at Llanelwedd, for the second time in three years.
14 November 2007 A further 24,000 turkeys are slaughtered as a precaution on four premises run by the same company as that which operates the infected farm.
12 November 2007 About 5,000 birds slaughtered after the H5 strain of avian flu is confirmed in turkeys at Redgrave Park Farm, Suffolk. A 3km protection zone and a 10km surveillance zone are set up.
7 June 2007 The low pathogenic H7 strain of bird flu is found at a smallholding near St Helens in Merseyside.
27 May 2007 Following the death of chickens at a farm in Conwy, North Wales, the low pathogenic H7N3 strain is confirmed.
9 March 2007 Defra announces that all remaining control measures will be lifted at one minute past midnight on 12 March. Poultry movement and sale will now be allowed in the area. The UK's chief vet urges bird keepers to remain vigilant.
Bernard Matthews takes out full-page adverts in several newspapers, telling the public: "My turkey is completely safe to eat."
8 March 2007 Public Health Minister Caroline Flint reveals that 850 tons of turkey passed through the plant and into the food chain during the outbreak. Nearly 100 tons came from Hungary, she says, but the Food Standards Agency says none of the meat went near infected birds.
1 March 2007 The 3km exclusion zone around the plant is lifted, meaning turkeys no longer have to stay indoors. The wider 10km surveillance zone remains in place.
27 February 2007 Bernard Matthews lays off another 38 workers. It blames the move on a fall in demand.
Anti-viral drugs are offered to 480 workers and clean-up staff. The Health Protection Agency says it is a precautionary measure.
22 February 2007 The government announces that bird flu has not been found anywhere else in the UK.
20 February 2007 Market information company AC Nielsen says turkey sales have fallen by up to one third across the UK.
19 February 2007 At least 130 Bernard Matthews workers are to be laid off. The Transport and General Workers' Union say employees at Great Witchingham, Norfolk, will be stood down for 20 days from Tuesday, but the company refuses to confirm details.
Environment Secretary David Miliband says the disease inquiry is still focused on links to Hungary. He says restrictions in Suffolk will not be lifted before the second week of March and warns there is a "continual risk" of more outbreaks.
16 February 2007 Imported poultry from Hungary is the "most plausible" cause of the UK bird flu outbreak, government scientists say in a report.
They also list various failings at the Bernard Matthews plant in Suffolk where the outbreak started - including gulls carrying waste from the site.
15 February 2007 Bernard Matthews speaks out in defence of his company for the first time, saying allegations that information may have been withheld are "completely untrue".
14 February 2007 Some Bernard Matthews turkey products are cleared by the Food Standards Agency (FSA) to be released for sale.
13 February 2007 Scientists say the strains of H5N1 bird flu found in England and Hungary are "essentially identical", as the Suffolk farm at the centre of the UK outbreak resumes the slaughtering and processing of turkeys.
Also, the government gives the Holton plant the go-ahead to restart operations - poultry is brought in under a special licence that allows it to cross into the exclusion zone around the site.
11 February 2007 Environment Secretary David Miliband defends the government's handling of the outbreak. He says a ban on imports from Hungary, where the virus is thought to have originated, would have breached EU rules.
10 February 2007 Supermarkets deny there has been a slump in poultry sales after the outbreak.
9 February 2007 Bernard Matthews defends its import policy and says meat products it brought to the UK from Hungary came from outside the infected bird flu zone. The FSA confirms it is investigating whether meat infected with bird flu could have entered the food chain.
8 February 2007 The Suffolk outbreak may be linked to imports from the Bernard Matthews plant in Hungary, a government vet says. Culled birds from three more sheds on the Holton farm show strains of H5N1. But two more workers involved in dealing with the cull test negative for bird flu.
7 February 2007 A vet who became ill after working at Holton tests negative for bird flu.
6 February 2007 The cull of 159,000 turkeys is completed, the government announces.
4 February 2007 Government vets start gassing infected birds at the Holton farm.
3 February 2007 The European Commission says tests confirm that the avian flu is the H5N1 virus.
1 February 2007 Vets are called to the Bernard Matthews farm, in Holton, Suffolk. Early tests suggests the H5 strain of avian flu is responsible for the deaths of 2,600 turkeys.
26 April 2006 Chickens test positive for bird flu - early tests suggests the H7 strain - at a farm near Dereham, Norfolk, leading to the slaughter of 35,000 birds. The H7 strain is virulent among chickens but less of a risk to humans than the H5N1 strain.
22 April 2006 Protection zone affecting how poultry is kept within 3km of where the dead swan was found is lifted. The 10km surveillance zone, where movement of poultry products is restricted - and the broader risk area - remain in place until at least the end of the month.
20 April 2006 Scotland's first minister announces that restrictions imposed in the wake of the discovery of the dead swan are to be lifted.
11 April 2006 Dead bird identified as a whooper swan, not native to the UK, but scientists remain unsure whether it contracted the disease abroad or after it arrived in Britain.
6 April 2006 H5N1 is confirmed in the swan, and Scotland's contingency plan is put into effect. Tests on more birds are carried out.
5 April 2006 Laboratory tests confirm the presence of highly-pathogenic H5 avian flu in the dead swan. Further tests are carried out to establish whether it is the lethal H5N1 strain.
A two-day exercise to test the UK's bird flu plans is abandoned so that resources can be switched to the Scotland incident.
31 March 2006 Samples from the bird are received at the main testing laboratories in Weybridge, Surrey, for further analysis.
30 March 2006 The swan is collected and taken away for laboratory tests.
29 March 2006 A mute swan found dead in the harbour at Cellardyke, near Anstruther, Fife, is reported to the authorities.
15 November 2005 Subsequent tests show the disease is most likely to have come from the finches rather than the parrot. A government report blames the confusion on a mix-up of tissue samples.
21 October 2005 The lethal H5N1 strain is confirmed in one of the parrots, but because the bird was in quarantine, the discovery does not affect the UK's disease-free status.
14 October 2005 Some of the finches and parrots are found dead and tested for bird flu.
27 September 2005 A group of finches arrives at the same quarantine premises in Essex as part of a mixed consignment of birds from Taiwan.
19 September 2005 Department of Health publishes its latest pandemic flu contingency plan. Scotland issues its own updated plan.
16 September 2005 A consignment of parrots arrives in quarantine in Essex from Surinam, in South America.