Article Info Authors Dr.Mohammed Hussain Hassan Al-OmriDr.Mohammed AbdulAziz Al-MazroaDr.Sami Saeed Saeed AlMudarra Volume: 18 Year: 2011 Month: July Issue: 3 Pages: Reference: Al-Omri M., Al-Mazroa M., AlMudarra S., .Saudi Epidemiology Bulletin. 2011;18(3):.