Professor Aziz Sheikh, Professor of Primary Care Research & Development and Co-Director of the University's Centre for Population Health Scientist, delivers the third lecture in the 2014 Medical Detectives series entitled, "The Sign of Three: Progress Report on an Investigation into the Epidemic of Itch, Sneeze and Wheeze". In this lecture, Professor Sheikh will present a summary of the main culprits identified to-date and share his thoughts on where the investigation should now focus attention. Recorded on 23 October 2014, at the University of Edinburgh's Anatomy Lecture Theatre.