It was back in 1997 when Hong Kong health authorities identified the first cases of bird flu virus being passed from birds to humans. It happened after an outbreak affected chickens and other fowl: 18 people caught the illness, six of whom died.The World Health Organisation reacted swiftly to the crisis. “It is possible that both bird to man and man to man transmission could occur,” an official said. Action in hospitals and by vets halted the spread of the disease. But the source of the infection, the H5N1 virus, didn’t go away. It remains common among birds in Asia. The strain can be transmitted through saliva and faeces. Millions of chickens and ducks have been slaughtered in recent years to stem the illness. The more recent outbreak, originally starting two years ago, affected eight Asian countries. Now it is spreading into Russia, Central Asia and Turkey. The World Health Organisation issued a fresh alert: the new strain can sometimes affect humans. The recent H5N1 virus has proved capable of being transmitted from fowl such as chickens. This proved fatal in several cases. In the past two years, there have been 116 cases of the human strain in Vietnam, Thailand, Cambodia and Indonesia, including 60 deaths. It is generally believed the virus is carried across the world by wild birds. In spite of drastic measures, including mass culling across South East Asia, the outbreak is working its way towards eastern Europe. Public health guidelines are widely available and doctors say they must be followed if a pandemic is to be avoided.