Table 5. Scrub typhus IgM sero-prevalence in hospitalised cases and controls, and estimated population attributable fractions (OD cut-off of 0.4).
| N | IgM+ (%) | AOR* | 95%CI | PAF | |
|---|---|---|---|---|---|
| Overall | |||||
| Control | 562 | 3.9% | Ref | - | - |
| Outpatient | 236 | 3.0% | 0.7 | 0.3 to 1.4 | NA |
| Hospitalised | 58 | 19.0% | 6.0 | 3.2 to 11.2 | 15.8% |
| By gender | |||||
| Females | |||||
| Control | 331 | 4.5% | Ref | - | - |
| Outpatient | 188 | 3.7% | 0.8 | 0.4 to 1.7 | NA |
| Hospitalised | 31 | 22.6% | 6.1 | 2.4 to 15.6 | 18.9% |
| Males | |||||
| Control | 231 | 3.0% | Ref | - | - |
| Outpatient | 48 | 0.0% | - | - | NA |
| Hospitalised | 27 | 14.8% | 5.9 | 1.4 to 23.9 | 12.3% |
| By age | |||||
| Age ≤35 years | |||||
| Control | 153 | 3.3% | Ref | - | - |
| Outpatient | 76 | 2.6% | 0.6 | 0.1 to 3.3 | NA |
| Hospitalised | 19 | 10.5% | 4.3 | 0.7 to 26.1 | 8.1% |
| Age >35 to 50 years | |||||
| Control | 222 | 5.4% | Ref | - | - |
| Outpatient | 66 | 1.5% | 0.3 | 0.1 to 1.2 | NA |
| Hospitalised | 16 | 25.0% | 6.0 | 1.6 to 21.8 | 20.8% |
| Age >50 years | |||||
| Control | 187 | 2.7% | Ref | - | - |
| Outpatient | 94 | 4.3% | 1.5 | 0.6 to 3.6 | 1.4% |
| Hospitalised | 23 | 21.7% | 10.2 | 2.6 to 39.4 | 19.6% |
| by village level IgG prevalence | |||||
| Low risk areas (IgG prevalence in controls <15%) | |||||
| Control | 254 | 2.0% | Ref | - | - |
| Outpatient | 84 | 2.4% | 0.9 | 0.2 to 3.8 | NA |
| Hospitalised | 29 | 6.9% | 4.4 | 0.6 to 33.0 | 5.3% |
| High risk areas (IgG prevalence in controls ≥15%) | |||||
| Control | 308 | 5.5% | Ref | - | - |
| Outpatient | 152 | 3.3% | 0.6 | 0.2 to 1.4 | NA |
| Hospitalised | 29 | 31.0% | 7.6 | 4.1 to 14.0 | 27.0% |
*logistic regression adjusted for sex and age (age / sex removed in respective analyses stratified by age and sex)