1. Infectious Disease Unit , Specialty Internal Medicine, Johns Hopkins Aramco Healthcare, Dhahran 31311 , Saudi Arabia
2. Department of Medicine , Indiana University School of Medicine, Indianapolis, IN 46202 , USA
3. Department of Medicine , Johns Hopkins University, Baltimore, MD 21093 , USA
4. Pediatric Department , King Abdullah Specialist Children’s Hospital(KASH), Riyadh 14611 , Saudi Arabia
5. Department of Medicine , King Saud Bin Abdulaziz University for -Health Sciences Riyadh 14611 , Saudi Arabia
6. Department of Medicine , King Saud Medical City, Ministry of Health, Al-Faisal University, Riyadh 11533 , Saudi Arabia
7. Hubert Department of Global Health , Rollins School of Public Health, Emory University, Atlanta, GA 30322 , USA