7:15pm UK, Friday September 29, 2006

The avian virus has been slowly spreading across the world for years.

More than 40 have died in Vietnam from the killer H5N1 strain. But death tolls are also rising in other countries.

180 Poultry

The virus has spread through poultry

Scientists fear the virus could mutate into a strain that passes between humans.

Chief medical officer Sir Liam Donaldson said a bird flu pandemic could kill thousands in Britain.

The Numbers:

148 - The number of worldwide bird flu deaths recorded so far.

55,000 - The number of deaths estimated by the Government if a pandemic hit the UK.

700,000 - The possible UK death toll in a worst case scenario.

7.4 million - The number of people who could die worldwide, according to the World Health Organisation.

50 million - The death toll from the 1918 flu pandemic.

150 million - The number of people who could die worldwide from bird flu, according to a United Nations official.

30 years - The interval between major flu pandemics.

1968 - The year of the last flu pandemic.

56 - The number of countries that have reported cases of the H5N1 strain, including: Korea, Vietnam, Japan, Thailand, Cambodia, Laos, Indonesia, China, Malaysia, Russia, Kazakhstan, Mongolia, Turkey, Romania, Croatia, Ukraine, Cyprus, Iraq, Nigeria, Egypt, India, France, Niger, Bosnia, Azerbaijan, Albania, Cameroon, Myanmar, Afghanistan, Israel, Pakistan, Jordan, Burkina Faso, Germany, Austria, Bulgaria, Czech Republic, Denmark, Greece, Hungary, Iran, Italy, Kuwait, Poland, Serbia and Montenegro, Slovakia, Slovenia, Sweden, Switzerland and UK.