TARA WOMERSLEY works on press and public relations for the College of Medicine and Veterinary Medicine at the University of Edinburgh. She started her career in journalism and has worked for newspapers including The Daily Telegraph and The Sunday Times and is a former health correspondent for The Scotsman. She was also involved in coordinating the media launch of the Make Poverty History campaign in Australia, while also working in media relations for an overseas aid agency. DOROTHY CRAWFORD qualified in medicine from St Thomas's Hospital, London and gained a PhD from Bristol University. She was appointed to the Robert Irvine Chair of Medical Microbiology at the University of Edinburgh in 1997 and was made Assistant Principal for Public Understanding of Medicine in 2007. She has published around 200 research papers on this subject and was elected a Fellow of the Royal Society of Edinburgh in 2001 and awarded an OBE for services to medicine and higher education in 2005. She is the author of The Invisible Enemy: A Natural History of Viruses, ISBN 9780198564812 and Deadly Companions: How microbes shaped our history, ISBN 9780199561445.