LAUSR

BACKGROUND Despite growth in the number of cruises worldwide, evidence about diarrhea experienced by cruise ship passengers remains sparse. We investigated rates of diarrhea and related factors among passengers on world cruises departing from Japan. METHODS Targeting passengers on five world cruises (n = 4180) from 2012 to 2013 (85-103 travel days), we calculated rates of health seeking behavior for diarrhea by sex, age group, and number of roommates for each cruise. We estimated rate ratios and 95% confidence intervals, using the group aged 20-39 years, women, and 2-4 roommates as referent categories. RESULTS We found 5.04-6.00 cases per 10,000 person-days in the five cruises, with an elevated number after calling at ports. Older passengers (>60 years) and passengers with fewer roommates had an elevated risk of health seeking behavior for diarrhea, although passengers aged <20 years had an elevated risk on one cruise. After controlling for covariates (including cruise), significant associations remained for passengers aged >60 years and without roommates. CONCLUSIONS Older passengers and passengers with fewer roommates may be more likely to seek medical treatment for diarrhea during travel on a world cruise, and should take preventive measures.