The H5N1 strain of avian flu isn't new. It was discovered in China in 1996. But in recent years it's started passing from mammal to mammal and it's now rife on cattle farms in the United States. How much should humans worry?
David Aaronovitch speaks to:
Professor Wendy Barclay, action medical research chair in virology at Imperial College London\nKai Kupferschmidt, science journalist and molecular biologist\nDr Caitlin Rivers, epidemiologist at the Johns Hopkins School of Public Health.\nProfessor Ian Brown, avian virology group at The Pirbright Institute
Production team: Sally Abrahams, Kirsteen Knight and Ben Carter\nEditors: Richard Vadon and Emma Rippon\nProduction Co-ordinator: Gemma Ashman\nSound engineers: Rod Farquhar