Table 4. Single- and multiple-variable conditional logistic regression analyses for identifying risk factors for scrub typhus.
| Exposure factors or risk behaviors | Missing data | Case | Control | Single-variable regression analysis | Multiple-variable regression analysis |
|---|---|---|---|---|---|
| n(%) | n(%) | OR(95% CI)** | OR(95% CI)** | ||
| Agricultural labor | 3 | 125(93.3) | 182(76.5) | 2.9(1.5–5.8)* | — |
| Places of agricultural labor | |||||
| Rice field | 2 | 122(91.0) | 171(71.5) | 2.8(1.5–5.0)* | — |
| Cotton field | 8 | 1(0.8) | 1(0.4) | 1.4(0.2–10.0) | — |
| Cornfield | 7 | 2(1.5) | 6(2.6) | 0.7(0.2–2.8) | — |
| Soya bean field | 1 | 61(45.9) | 128(53.1) | 0.8(0.6–1.2) | — |
| Sweet potato field | 3 | 62(46.6) | 120(50.2) | 0.9(0.7–1.3) | — |
| Vegetable field | 2 | 96(72.2) | 183(76.0) | 0.9(0.6–1.3) | — |
| Bundling up or moving waste straw | 31 | 115(92.7) | 80(36.4) | 9.8(5.0–19.2)* | 9.0(4.6–17.8)* |
| Frequency of bundling up or moving waste straw | |||||
| none | 7(5.6) | 139(63.2) | Reference | ||
| 1–2 times every two weeks | 42(33.9) | 59(26.8) | 6.9(3.4–14.1) | ||
| 3–4 times every two weeks | 37(29.8) | 19(8.6) | 10.9(5.3–22.7) | ||
| ≥5 times every two weeks | 36(29.0) | 2(0.9) | 15.7(7.6–32.6) | ||
| Grazing | 7 | 1(0.8) | 1(0.4) | 1.4(0.2–10.1) | — |
| Fishing | 7 | 4(3.1) | 6(2.5) | 1.1(0.4–3.1) | — |
| Resting on the grass | 1 | 11(8.3) | 30(12.4) | 0.7(0.4–1.4) | — |
| Morning exercise outdoor | 8 | 3(2.3) | 1(0.4) | 2.1(0.7–6.7) | — |
| Washing by the river | 7 | 34(25.8) | 80(33.9) | 0.8(0.5–1.1) | — |
| Living at the edge of villiage | 9 | 34(25.4) | 112(48.3) | 0.5(0.4–0.8)* | 0.6(0.4–0.9)* |
| Stacking waste straw indoors | 10 | 33(24.6) | 29(12.6) | 1.6(1.1–2.4)* | — |
| Living aroud the grass | 11 | 117(88.0) | 197(85.3) | 1.2(0.7–2.0) | — |
| The type of fuel | |||||
| Gas | 10 | 119(88.8) | 196(84.8) | 1.3(0.7–2.2) | — |
| Waste straw | 12 | 99(73.9) | 158(69.0) | 1.2(0.8–1.7) | — |
| Firewood | 15 | 59(44.4) | 130(57.3) | 0.7(0.5–1.0) | — |
| Raising poultry and livestock | 10 | 61(45.5) | 99(42.9) | 1.1(0.8–1.5) | — |
| Mouse activities indoors | 0 | 92(68.7) | 131(54.4) | 1.4(0.9–2.2) | — |
| Similar cases in the family | 0 | 2(1.5) | 3(1.2) | 1.1(0.3–4.4) | — |
*:P≤0.05.
**:OR = odds ration;CI = confidence interval.