Table 1. Results of univariable analysis of risks for illness caused by Escherichia coli O157 in visitors to an open farm, Walesa.
| Exposure | Cases | Controls | Univariable analysis | ||||
|---|---|---|---|---|---|---|---|
|
|
Exposed/ not exposed |
Exposed/ not exposed |
Odds ratio |
p value |
95% CI |
||
| Contact with animals |
|
|
|
|
|
||
|
|
Cows |
11/2 |
16/20 |
6.88
|
0.01
|
1.15 to 52.69 |
|
|
|
Goats (any contact) |
13/0 |
27/9 |
Undef |
0.09 |
Undef |
|
|
|
Goat (high contact) |
10/3 |
17/19 |
3.72
|
0.06
|
0.75 to 20.70 |
|
|
|
Rabbit |
9/4 |
20/16 |
1.80 |
0.39 |
0.40 to 8.62 |
|
|
|
Sheep |
10/3 |
27/9 |
1.11 |
1.00 |
0.21 to 6.48 |
|
|
|
Pigs |
5/7 |
11/24 |
1.56 |
0.72 |
0.33 to 7.32 |
|
|
|
Pony |
4/9 |
20/16 |
0.36 |
0.12 |
0.07 to 1.61 |
|
|
|
Shire horse |
4/9 |
13/23 |
0.79 |
1.00 |
0.16 to 3.64 |
|
| Areas of farm visited |
|
|
|
|
|
||
|
|
Play area |
5/7 |
27/9 |
0.24 |
0.07 |
0.05 to 1.13 |
|
|
|
Paddock |
6/7 |
28/8 |
0.24 |
0.08 |
0.05 to 1.13 |
|
|
|
Pony ride |
4/9 |
15/21 |
0.62 |
0.49 |
0.13 to 2.84 |
|
|
|
Tractor ride |
9/4 |
28/8 |
0.64 |
0.71 |
0.13 to 3.31 |
|
|
|
Main barn |
13/0 |
35/1 |
Undef |
1.00 |
Undef |
|
| Food consumption and personal behaviors |
|
||||||
|
|
Sucks thumb |
1/11 |
6/30 |
0.45 |
0.66 |
0.02 to 4.74 |
|
|
|
Bites nails |
2/10 |
6/30 |
1.00 |
1.00 |
0.12to 7.08 |
|
|
|
Ate any food while on farm |
13/0 |
33/3 |
Undef |
0.56 |
Undef |
|
|
|
Ate immediately after barn |
6/6 |
11/23 |
2.09 |
0.31 |
0.45 to 9.81 |
|
|
|
Ate food bought on farm |
8/5 |
14/21 |
2.40 |
0.18 |
0.55 to 10.85 |
|
|
|
Ate ice cream |
9/4 |
14/22 |
3.54
|
0.06
|
0.77 to 17.19 |
|
|
|
Ate cotton candy |
7/6 |
4/32 |
9.33
|
0.004
|
1.69 to 57.10 |
|
|
|
Bought animal feed |
10/3 |
32/4 |
0.42 |
0.36 |
0.06 to 2.88 |
|
|
|
Picked up animal feed from floor |
5/8 |
6/30 |
3.13 |
0.13 |
0.61 to 16.29 |
|
|
|
Ate animal feed |
1/12 |
0/36 |
Undef |
0.26 |
Undef |
|
|
|
Clung to animal barriers |
6/3 |
25/7 |
0.56 |
0.66 |
0.09 to 3.76 |
|
|
|
Fell over while on farm |
1/12 |
7/29 |
0.35 |
0.66 |
0.01 to 3.43 |
|
|
|
Washed hands at all |
10/3 |
24/9 |
1.12 |
1.00 |
0.23 to 7.35 |
|
| Environmental observations |
|
|
|
|
|
||
|
|
Wet underfoot |
3/10 |
6/30 |
1.50 |
0.68 |
0.24 to 8.85 |
|
|
|
Dirty hands, shoes, or clothes |
0/13 |
9/27 |
0.00 |
0.09 |
0.00 to 1.46 |
|
|
|
Noticed queue for toilets |
2/10 |
3/32 |
2.13 |
0.59 |
0.21 to 19.56 |
|
| Type of visit |
|
|
|
|
|
||
|
|
Family visit |
12/1 |
33/3 |
0.92 |
1.00 |
0.08 to 30.07 |
|
| Bank Holiday Monday | 11/2 | 13/20 | 9.73 | 0.003 | 1.38 to 66.32 | ||
aCI, confidence interval; undef, undefined. (When one of the cells contains a zero, defining a confidence interval is not possible.) Bold typeface highlights variables with increased odds ratio statistically significant at 90% level.