Mass Gatherings and Diarrheal Disease Transmission among Rural Communities in Coastal Ecuador.

Mass gatherings exacerbate infectious disease risks by creating crowded, high-contact conditions, and straining the capacity of local infrastructure. While mass gatherings have been extensively studied in the context of epidemic disease transmission, the role of gatherings in incidence of high-burden, endemic infections has not been previously studied. Here, we examine diarrheal incidence among seventeen communities in Esmeraldas, Ecuador, in relation to recurrent gatherings characterized using ethnographic data collected during and after the epidemiological surveillance period (2004-2007). Using distributed lag generalized estimating equations, adjusted for seasonality, trend, and heavy rainfall events, we found significant increases in diarrhea risk in host villages, peaking two weeks after an event's conclusion (incidence rate ratio (IRR): 1.21, confidence interval (CI), adjusted for false discovery rate ≤ 0.05: 1.02, 1.43). Stratified analysis revealed heightened risks associated with events where crowding and travel were most likely (2-week lag IRR 1.51; CI, adjusted for false discovery rate ≤ 0.05: 1.09, 2.10). Our findings suggest that community-scale mass gatherings may play an important role in endemic diarrheal disease transmission and could be an important focus for interventions to improve community health in low resource settings.