International audienceBackground: Diarrhea can be frequent among Hajj pilgrims; however, data on its etiology are very limited. Patients and methods: A prospective cohort study was conducted among Hajj pilgrims in 2016. Medical follow-up and systematic rectal swabing were performed before leaving France and before leaving Saudi Arabia. Potential pathogens were identified using the BioFire FilmArray (R) Gastrointestinal multiplex qualitative PCR panel. Results: 117 pilgrims were included and 13.7% experienced diarrhea during Hajj. Of the pre-Hajj samples, 32.5% were positive for at least one pathogen compared to 50% of post-Hajj samples (p = 0.0033). Diarrhea associated Escherichia coli. strains, notably enteropathogenic E. coli (EPEC), ente...