1. Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
2. Centre for Enteric Diseases, National Institute for Communicable Diseases, a division of the National Health Laboratory Service, Johannesburg, South Africa
3. University of East Anglia, Norwich, UK
4. National Microbiology Reference Laboratory, Harare, Zimbabwe
5. Unit of Chemistry and Environmental Microbiology, Pasteur Institute, Ivory Coast