Table 2. Univariate and multivariate analysis of risk factors for symptomatic NoV infections, Vietnam, 2009–2010*.
| Risk factor | NoV-positive case-patients | NoV-negative control participants | OR | 95% CI | aOR | 95%CI |
|---|---|---|---|---|---|---|
| Mean age, mo (range) | 13.3 (2–45) | 16.8 (0–60) | 0.97 | 0.96–0.99 | 0.96 | 0.94–0.98 |
| Male sex (%) | 147 (61.0) | 314 (53.0) | 1.38 | 1.0–1.9 | 1.38 | 0.9–2.0 |
| Poor Z-score |
18 (7.5) |
75 (12.7) |
0.56
|
0.3–0.9 |
0.61 |
0.3–1.1 |
| Low income† | 150 (62.2) | 335 (56.6) | 1.26 | 0.9–1.7 | 0.89 | 0.6–1.3 |
| ≥5 adults in hh | 72 (29.9) | 158 (26.7) | 1.17 | 0.8–1.6 | NI | x |
| ≥3 children in hh |
36 (14.9) |
58 (9.8) |
1.62
|
1.0–2.5 |
1.70
|
1.0–2.9 |
| Refrigerator in hh | 187 (77.6) | 506 (85.5) | 0.59 | 0.4–0.9 | 0.73 | 0.5–1.2 |
| Consumes market food |
201 (84.1) |
345 (58.4) |
3.77
|
2.6–5.5 |
4.99
|
3.1–7.9 |
| Household water source | ||||||
| Pipeline‡ | 132 (54.8) | 347 (58.6) | 1.00 | NA | NI | NI |
| Well | 96 (39.8) | 220 (37.2) | 1.15 | 0.8–1.6 | NI | NI |
| Other§ | 13 (5.4) | 25 (4.2) | 1.37 | 0.7–2.8 | NI | NI |
| Drinking water source | NI | NI | NI | NI | NI | NI |
| Pipeline‡ | 116 (48.1) | 334 (56.4) | 1.00 | NA | 1.00 | NA |
| Bottled water | 69 (28.6) | 122 (20.6) | 1.63 | 1.1–2.3 | 2.18 | 1.4–3.4 |
| Well | 42 (17.4) | 109 (18.4) | 1.11 | 0.7–1.7 | 0.94 | 0.6–1.5 |
| Other§ |
14 (5.8) |
1.49 |
0.8–2.9 |
0.25 |
1.45 |
0.6–3.2 |
| Toilet type | ||||||
| Indoor‡ | 213 (90.6) | 446 (75.9) | 1.00 | NA | 1.00 | NA |
| Outdoor | 22 (9.4) | 142 (24.2) | 0.32 | 0.2–0.5 | 0.22 | 0.1–0.4 |
| Hand washing¶ |
130 (85.0) |
291 (89.5) |
0.66 |
0.4–1.2 |
NI |
NI |
| Attends day care/nursery school | 30 (12.5) | 89 (15.2) | 0.80 | 0.5–1.2 | NI | NI |
| Contact with symptomatic persons | 38 (16.5) | 8 (1.4) | 14.23 | 6.5–31.0 | 26.14 | 10.4–65.9 |
| Rural residence# | 36 (14.9) | 75 (12.7) | 1.21 | 0.8–1.9 | NI | NI |
*Values are no. case (%) unless otherwise specified. Values in boldface indicate statistical significance at p≤0.05. NoV, norovirus; OR, odds ratio; aOR, adjusted OR; NA, not applicable; NI, not included in multivariable analysis; hh, household. †Classified as making less than the Gross National Income ($232/mo) according to World Bank (http://data.worldbank.org/indicator/NY.GNP.PCAP.CD). ‡Reference group. §Rain water, water from a truck provided by the government, or other water source. ¶Washing of children’s hands, either by an adult or the child, after the child uses the toilet. #Binh Chanh, Can Gio, Cu Chi, Hoc Mon, and Nha Be districts.