Table 2. Model 1 — Risk factors associated with Avian Influenza type H9N2 infection on commercial poultry farms in Pakistan based on a backward manual stepwise selection process on all variables available in Table 1.
| Potential risk factors | Response levels | Regression coefficient | Standard error | OR | 95% CI for OR | p-value |
|---|---|---|---|---|---|---|
| Distance from the nearest commercial farm | >1km | 1 | ||||
| ≤1km | -1.3082 | 0.6068 | 0.270 a | 0.082–0.888 | 0.031 | |
| Distance from the nearest case/infected farm | >1km | 1 | ||||
| ≤1km | 3.7927 | 0.7690 | 44.4 b | 9.83–200 | <0.001 | |
| History of Infectious Bursal Disease in the flock | No | 1 | ||||
| Yes | 1.1753 | 0.4701 | 3.20 c | 1.29–8.14 | 0.012 | |
| Selling of birds/eggs directly to the live bird retail stalls | No | 1 | ||||
| Yes | 2.0397 | 0.6828 | 7.69 d | 2.02–29.3 | 0.002 |
R2 = 0.365 (out of a possible 0.5)
aThe odds of being near the other commercial farm<1km was 0.270 (CI 95%: 0.082–0.888) times less in case farm than the odds of exposure in the control farms
b The odds of being near the case/other infected farm<1km was 44.4 (CI 95%: 9.83–200) times greater than the odds of exposure in the control farms.
cThe odds of having history of infection with IBD for case was 3.20 (95% CI: 1.29–8.14) times greater than the odds of exposure in the control farm.
dThe odds of selling the birds/and or eggs directly to live bird retail shops was 7.69 (CI 95%: 2.02–29.3) times more than the odds of exposure in the control farms.