Department of Physiology, School of Biomedical Sciences, College of Health Sciences, Makerere University, Kampala, Uganda. Department of Internal Medicine, School of Medicine, College of Health Sciences Unit Makerere University, Kampala, Uganda. Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine Uganda Research Unit, Entebbe, Uganda. Pulmonary Division, Department of Internal Medicine, Mulago National Referral Hospital, Kampala, Uganda. Department of Immunology and Molecular Biology, School of Biomedical Sciences, College of Health Sciences, Makerere University Kampala, Uganda. Department of Policy and Development Economics, School of Economics, College of Business and Management Sciences Makerere University, Kampala, Uganda. Infectious Diseases Institute, College of Health Sciences, Makerere University, Kampala, Uganda.