1. Department of Epidemiology Johns Hopkins University Bloomberg School of Public Health Baltimore Maryland USA
2. Department of Emergency Medicine Johns Hopkins University School of Medicine Baltimore Maryland USA
3. Macha Research Trust Macha Zambia
4. Division of Infectious Diseases Johns Hopkins University School of Medicine Baltimore Maryland USA
5. Virology Laboratory University Teaching Hospital Lusaka Zambia
6. Department of Microbiology and Immunology Johns Hopkins University Bloomberg School of Public Health Baltimore Maryland USA