Incidence of stomach upset on land- and cruise-based holidays to countries for which >100 CSQs were received from cruise passengers.

a : Country of cruise departure for cruises, country of holiday stay for land-based holidays. It is expected that most cruises will stop at many ports and allow shore trips, so the departure country may not reflect the exposure risks on the cruise.
b : UK cruise data only available from 2005 onwards.
c : Cases of stomach upset (and as a % of total passenger trips.
Please note that because the sample size is very large and therefore even small effects will appear significant we have chosen P<0.0005 as a cut-off value compared to p values used in other smaller studies (i.e. P<0.01).