This project was done by Khairollah Asadollati and Yehmane Azizpour, master students in epidemiology from Ilam University of Medical Sciences, Iran. They are about to graduate in 2 months and have contributed to almost all phases of the study. Azizpour Y. proposed the first idea, coordinated the project and carried out the design. Asadollahi K. is a professor of epidemiology at the Faculty of Health and Social Medicine in the Faculty of Health in Ilam University of Medical Sciences, Iran. He supervised the student and participated in most steps of the study, including the design and the analysis.