Table 2.
Univariable and multivariable risk factors for secondary Shigella transmission to 337 contacts within 102 households*, Amsterdam, The Netherlands 2002–2009
| Exposure | Total no. of household contacts | Any secondary transmission | Univariable | Multivariable | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |
N |
n |
% |
RR |
95% CI |
p value |
RR |
95% CI |
p value |
|||
| |
|
|
|
|
|
Lower |
Upper |
|
|
Lower |
Upper |
|
|
Contact characteristics (n=337 contacts) | ||||||||||||
| Total |
|
337 |
25 |
7.4 |
n/a |
n/a |
n/a |
n/a |
n/a |
n/a |
n/a |
n/a |
| Age-group | ||||||||||||
| |
≥ 6 years |
260 |
17 |
6.5 |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
| |
0–3 |
48 |
3 |
6.3 |
1.0 |
0.3 |
3.3 |
0.943 |
1.0 |
0.3 |
3.2 |
0.979 |
| |
4–5 |
29 |
5 |
17.2 |
2.6 |
1.0 |
6.8 |
0.046 |
1.3 |
0.6 |
3.0 |
0.527 |
| Gender | ||||||||||||
| |
Female |
171 |
17 |
9.9 |
ref. |
ref. |
ref. |
ref. |
|
|
|
|
| |
Male |
166 |
8 |
4.8 |
0.5 |
0.2 |
1.2 |
0.109 |
|
|
|
|
| Country of birth | ||||||||||||
| |
Netherlands / Other Western |
97 |
7 |
7.2 |
ref. |
ref. |
ref. |
ref. |
|
|
|
|
| |
Other |
236 |
18 |
7.6 |
1.1 |
0.5 |
2.3 |
0.890 |
|
|
|
|
| Diarrhoea | ||||||||||||
| |
No |
228 |
5 |
2.2 |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
| |
Yes |
87 |
20 |
23.0 |
10.5 |
3.7 |
29.9 |
<0.001 |
8.0 |
2.7 |
23.8 |
<0.001 |
| Hospitalised | ||||||||||||
| |
No |
336 |
24 |
7.1 |
ref. |
ref. |
ref. |
ref. |
|
|
|
|
| |
Yes |
1 |
1 |
100.0 |
- |
- |
- |
- |
|
|
|
|
|
Household factors (n=102 households) | ||||||||||||
| Household size | ||||||||||||
| |
2–4 persons (in 61 households) |
128 |
5 |
3.9 |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
| |
5–6 persons (in 24 households) |
96 |
5 |
5.2 |
1.3 |
0.4 |
4.8 |
0.658 |
1.4 |
0.4 |
4.6 |
0.570 |
| |
>6 persons (in 17 households) |
113 |
15 |
13.3 |
3.4 |
1.3 |
8.7 |
0.011 |
3.1 |
0.9 |
10.1 |
0.064 |
| Age of primary case in household | ||||||||||||
| |
≥ 6 years |
218 |
11 |
5.1 |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
ref. |
| |
0–3 |
58 |
6 |
10.3 |
2.1 |
0.8 |
5.5 |
0.152 |
2.6 |
1.0 |
7.1 |
0.061 |
| |
4–5 |
61 |
8 |
13.1 |
2.6 |
1.2 |
5.7 |
0.018 |
1.9 |
0.8 |
4.5 |
0.163 |
| Gender of primary case in household | ||||||||||||
| |
Female |
174 |
9 |
5.2 |
ref. |
ref. |
ref. |
ref. |
|
|
|
|
| |
Male |
163 |
16 |
9.8 |
1.9 |
0.9 |
4.1 |
0.103 |
|
|
|
|
| Primary case in household hospitalised | ||||||||||||
| |
No |
264 |
21 |
8.0 |
ref. |
ref. |
ref. |
ref. |
|
|
|
|
| |
Yes |
73 |
4 |
5.5 |
1.0 |
0.9 |
1.2 |
0.405 |
|
|
|
|
| Time from date of onset to notification of primary case | ||||||||||||
| |
≤1 week |
95 |
9 |
9.5 |
ref. |
ref. |
ref. |
ref. |
|
|
|
|
| |
1–3 weeks |
146 |
8 |
5.5 |
0.6 |
0.2 |
1.5 |
0.262 |
|
|
|
|
| >3 weeks | 96 | 8 | 8.3 | 0.9 | 0.4 | 2.0 | 0.761 | |||||
*The unit of analysis is the individual contact (n=337) and cluster characteristics are at the household level: household size, age and gender of the primary case in the household, whether they were hospitalised and time from date of onset to notification of primary case, as above.