Table 5. Probability of outbreak occurrence according to the number of acute gastroenteritis cases per 1,000 passengers during the first two and three days of a cruise, Cuba, Cyprus, Dominican Republic, Egypt, France, Greece, Italy, Portugal, Spain and the United Kingdom, 2010–2013.
| Number of acute gastroenteritis cases per 1,000 passengers | All cruises (n = 760) | Cruises ≥ 7 days long (n = 427) | ||||
|---|---|---|---|---|---|---|
| Probability of an outbreak (PPV, %) | ROC area | 95% CI | Probability of an outbreak (PPV, %) | ROC area | 95% CI | |
| First two days of the cruise | ||||||
| 1 | 4.63 | 0.74 | 0.55–0.93 | 6.49 | 0.75 | 0.54–0.92 |
| 2 | 6.82 | 8.82 | ||||
| 3 | 6.68 | 7.69 | ||||
| 4 | 11.07 | 12.51 | ||||
| First three days of the cruise | ||||||
| 1 | 3.50 | 0.87 | 0.72–1.00 | 4.83 | 0.87 | 0.71–1.00 |
| 2 | 7.61 | 9.73 | ||||
| 3 | 14.64 | 17.14 | ||||
| 4 | 22.76 | 25.03 | ||||
| 5 | 23.10 | 33.37 | ||||
PPV: positive predictive values; ROC: Receiver Operating Characteristic