Table 1.

Association of clinically defined illness and consumption of specific foods on 15 July 1996 in three schools

FoodNo. of subjectsAttack rate (%) for the following subjects:Relative risk95% CIP value by χ2 test
AffectedUnaffected
ExposedUnexposedExposedUnexposedExposedUnexposed
Bread646239835839.728.41.400.85–2.290.0427
Milk642279895239.434.21.150.72–1.850.3564
Tuna paste642279489340.422.51.791.16–2.790.0001
Soup640299538840.224.81.621.05–2.500.0010
Ice cream25256363128.413.92.040.79–5.310.0572