1. Department of Medicine, Faculty of Medicine Siriraj Hospital Mahidol University Bangkok Thailand
2. Department of Pharmacology, Faculty of Medicine Siriraj Hospital Mahidol University Bangkok Thailand
3. Department of Epidemiology Johns Hopkins Bloomberg School of Public Health Baltimore Maryland USA
4. Department of Microbiology, Faculty of Medicine Siriraj Hospital Mahidol University Bangkok Thailand
5. Clinical Epidemiology Unit, Department of Research and Development, Faculty of Medicine Siriraj Hospital Mahidol University Bangkok Thailand