1. Department of General Surgery, Northwick Park Hospital, Harrow, London HA1 3UJ, UK
2. Imperial College London Faculty of Medicine, London SW7 2AZ, UK
3. Department of Pathology, St. Mark’s Hospital, Harrow, London HA1 3UJ, UK
4. Department of Pathology, University College Hospital, London NW1 2BU, UK
5. Department of Infectious Diseases, Northwick Park Hospital, Harrow, London HA1 3UJ, UK