1. Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh;
2. Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, Geneva, Switzerland;
3. Department of Microbiology and Immunology, McGill University, Montreal, Canada;
4. Centre for Medicine and Society, University Medical Centre Freiburg, Freiburg, Germany