BACKGROUND: The Grand Magal of Touba (GMT) is a large event gathering around 4-5 million participants every year. A pilot study conducted in 2017 among GMT pilgrims showed that 41.8% of participants reported respiratory symptoms, mostly due to rhinovirus (13.0%), coronaviruses (16.0%) and adenovirus (4.6%). METHODS: A PCR-based prospective cohort study was conducted among GMT pilgrims and controls (who did not participate to the event) in two rural villages in South Senegal, in 2019. RESULTS: 93 pilgrims and 84 controls were included in the study. There were no significant differences between pilgrims and controls regarding demographic characteristics and chronic conditions. 60.2% of pilgrims reported respiratory symptoms during their stay in Touba, or soon after their return. By contrast, only 8.3% of controls reported respiratory symptoms after the GMT. The acquisition of rhinovirus, coronaviruses, Streptococcus pneumoniae and Moraxella catarrhalis was 22.6%, 6.5%, 17.2% and 6.8% respectively in pilgrims and was significantly higher than in controls (3.6%, 0%, 4.8% and 1.2% respectively). Respiratory symptoms post-GMT were five times more frequent in S. pneumoniae carriers (aOR = 5.18, 95%CI = [1.98-13.57]). CONCLUSION: This study demonstrates that individuals who participated in the GMT were at higher risk of suffering from respiratory symptoms and that this was linked to the acquisition of S. pneumoniae.