This study examines the feasibility of using a smartphone application (app) to conduct surveys among travellers during the Hajj pilgrimage. where the use of apps has not been evaluated for infectious disease surveillance. A longitudinal study was conducted among pilgrims at the Hajj 2014 using an iPhone app with separate questionnaires for three study phases covering before. during. https://www.mabelandfoxs.shop/product-category/educational-toys/