Melvyn Bragg and his guests discuss the origins of infectious disease. Infectious disease has been with us for millennia. There are reports of ancient outbreaks of plague in the Bible, and in numerous historical sources from China, the Middle East and Europe. Other infections, including smallpox, tuberculosis and measles, have also been known for centuries. But some diseases made their first appearances only recently: HIV emerged around a century ago, while the Ebola virus was first recorded in the 1970s.But where do the agents of disease come from, and what determines where and when new viruses and bacteria appear? Modern techniques allow scientists to trace the histories of infective agents through their genomes; the story of disease provides a fascinating microcosm of the machinery of evolution.With:Steve JonesProfessor of Genetics at University College LondonSir Roy AndersonProfessor of Infectious Disease Epidemiology at Imperial College LondonMark PallenProfessor of Microbial Genomics at the University of Birmingham.Producer: Thomas Morris.