Need help with a homework for Principles of Epidemiology class.

NAME: ___________________________________

Example of a cohort study

The Table below is based on an outbreak of gastroenteritis following a church supper. Of the 80 persons attending the supper, 75 were interviewed. Forty-six met the case definition. Attack rates were calculated for those who did and did not eat each of the 14 food items.

Number of persons who ate food item Number of persons who did not eat food item

	Ill	Total	Attack rate (%)	Ill	Total	Attack rate (%)
Baked ham	29	46		17	29
Spinach	26	43		20	32
Mashed potatoes	23	37		23	37
Cabbage salad	18	28		28	47
Jello	16	23		30	52
Rolls	21	37		25	38
Brown bread	18	27		28	48
Milk				44	71
Coffee	19	31		27	44
Water	13	24		33	51
Cakes	27	40		19	35
Vanilla Ice Cream	43	54			21
Choc. Ice Cream	25	47		20	27
Fruit salad				42	69

Figure out the Attack rates (%) for each food item by people who ate the food and people who did not eat the food. Do a 2 x 2 table for each food item and figure out the relative risk (RR) for each food item. For this assignment only include the 2 x 2 table of the item you think is most likely responsible for the outbreak. What is the food item you think most likely caused the outbreak and what is the RR for this food item?

Example of a case-control study

In the Table below, figure out the Odds Ratios for exposure to foods served in a hospital that had a salmonellosis outbreak. Sixty-five patients and staff member met the case definition. Their exposures to specified foods were compared to those of 62 healthy patients and staff members. From the Odds Rations you calculated for each food item, what food item most likely is the cause of the outbreak and what was the Odds Ratio for this item?

Cases (n = 65) Controls (n = 62)

	Ate	Did Not Eat	Ate	Did Not Eat	Odds Ratio
French onion soup		51	15	45
Baked ham	21	37	18	42
Parsley sauce	18	40	15	45
Cold salads		54		52
Creamed potatoes	23	35	23	35
Turnips and cabbage	30	29	21	38
Chicken curry rice	15	44		53
Sandwiches		53		56
Danish pastries		58		53
Chocolate mousse cake	42	16		53
Ice cream	10	48	16	43
Scones		58		56