Association Between Coastal Water Exposure and Urinary Tract Infection in Adult Females ​

Gastrointestinal illness is a known risk of swimming in coastal waters which are contaminated by sewer overflows, septic tanks, domestic pets, or wildlife. Limited research has assessed the risk of urinary tract infections (UTIs) from recreating in coastal waters, even though they are an established reservoir of UTI pathogens. We performed a prospective study of beachgoers in Santa Cruz, California over the summer of 2022 to examine the association between baseline recreational water and sand contact and subsequent UTI symptoms among adults who were assigned female at birth. We additionally analyzed surveillance data on fecal indicators in the same recreational water on dates when participants enrolled in the study. We observed significant increases in gastrointestinal illness and UTI among swimmers compared to non-swimmers. UTI risk was associated with the type of exposure; odds ratios (ORs) increased from waist deep submersion (OR = 3.1; 95% CI: 1.4-6.9) to head submersion (OR = 5.1; 95% CI: 1.7-18.9) to swallowed water (OR = 8.69; 95% CI: 2.2-33.9). Among water quality samples across sites and study dates, 15% exceeded advisory thresholds, including fecal coliform, Enterococcus, and E. coli limits. These results suggest a need to better characterize dose-response relationships between exposures to fecally contaminated recreational water and UTI risk.