Rhehab has worked in family planning, reproductive, maternal, new born, and child health for over 20 years. Many of these years have been in managing TB and HIV and AIDS Programs and projects at national, regional and global level. He advocated for the access of ARVs by HIV infected persons in Sub-Saharan Africa. He coordinated the first ever joint TB-HIV project in Africa with its lessons learned resulting into the development of the Global Policy for TB-HIV Services. He has published articles based on the experience in the field to find solutions to saving lives especially on TB and HIV prevention, care and support.