1. Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
2. School of Public Health, University of Ghana, Accra, Ghana
3. Department of Medicine, University of Zambia
4. University Teaching Hospital, Zambian Ministry of Health
5. Department of Medicine, Levy Mwanawasa Medical University, Lusaka, Zambia
6. Department of Infectious Diseases, Bern University Hospital
7. Division of Infectious Diseases, University of California at Los Angeles, Los Angeles, California
8. Division of Gastroenterology, Massachusetts General Hospital, Boston, USA
9. Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
10. Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, USA.