1. Department of Medicine, Bayero University, Kano, Nigeria
2. Institute of Human Virology, University of Maryland, Baltimore, Maryland, United States
3. Department of Family and Community Medicine, Meharry Medical College, Nashville, Tennessee, United States
4. Department of Preventive Medicine, Vanderbilt University School of Medicine, Nashville Tennessee, United States
5. Medicine Infectious Diseases Section, King Fahad Medical City, Riyadh, Saudi Arabia