The data contained in this worksheet provides the Median Fluorescence Intensity (MFI) readings from saliva samples serially collected during the Boquerón Beach, Puerto Rico study. Samples were analyzed using the bead-based multiplex immunoassay to assess immunoconversions in the beachgoers to multiple waterborne pathogens. In the study, we collected an initial sample (S1) at the beach and the remaining samples (S2 and S3) were self-collected by participants 10 -14 and 30 - 40 days later, respectively. This dataset is associated with the following publication: Simmons, K.J., T. Eason, C.L. Curioso, S. Griffin, M.K.D. Ramudit, K. Oshima, E. Sams, T. Wade, A. Grimm, A. Dufour, and S. Augustine. Visitors to a Tropical Marine Beach Show Evidence of Immunoconversions to Multiple Waterborne Pathogens. Frontiers in Public Health. Frontiers, Lausanne, SWITZERLAND, issue}: 231, (2019).