Here's what the experts say: Lee Jong-wook, director-general of the World Health Organisation: 'The world recognises this is a major public health challenge. The WHO is ready to focus its resources to reduce the risk of a human pandemic.' Bernard Vallat, director-general of the World Organisation for Animal Health: 'It [H5N1 bird flu] is worse now than in 1997 because the capacity to infect birds, the capacity to spread, the pathogenicity, the number of birds dying is worse than before.' Louise Fresco, assistant director-general of the Food and Agriculture Organisation: 'Fighting the disease in animals is key to our success in limiting the threat of a human pandemic.' David Nabarro, senior United Nations system co-ordinator for avian and human influenza: 'This is an issue that is very high up on the agenda of the international organisations because so many political leaders are saying to us, 'we need you to take this seriously and to help us'.' Margaret Chan Fung Fu-chun, representative of WHO director-general for pandemic influenza: 'We have been saying this for a long time: avian influenza is a big problem. The risk of a pandemic is great.' Leung Pak-yin, Hong Kong's controller of Centre for Health Protection: 'Unpredictable and yet inevitable. Only those who prepare well can respond well.'