1 Guy's, King's and St Thomas' School of Medicine, King's College London, London SE1 1UL, UK; London School of Hygiene & Tropical Medicine, London, UK. Electronic address: faheem.ahmed@kcl.ac.uk.
2 St George's Hospital, London, UK.
3 London School of Hygiene & Tropical Medicine, London, UK; King's College Hospital, London, UK.
4 HOPE Foundation for Women and Children of Bangladesh, FL, USA.
5 Guy's, King's and St Thomas' School of Medicine, King's College London, London SE1 1UL, UK.
6 London School of Hygiene & Tropical Medicine, London, UK; Nuffield Orthopaedic Centre, University of Oxford, Oxford, UK.