Table 1. LPAIV surveillance data collated from poultry farms, the Netherlands, 2007–2013*.
| Type of farm | No. farms positive | Total no, farms | Median time at risk, mo | Median distance to wild water bird areas, m | Median distance to medium- sized waterway, m† | Probability of introduction‡ | RR§ |
|---|---|---|---|---|---|---|---|
| Indoor-layer | 60 | 5,600 | 7.3 | 4,227 | 769 | 0.001 | 1 |
| Outdoor-layer | 143 | 2,549 | 6.3 | 3,996 | 670 | 0.009 | 6.0 |
| Layer-breeder | 14 | 2,174 | 9.5 | 4,157 | 738 | 0.001 | 0.5 |
| Broiler | 2 | 5,409 | 1.2 | 3,292 | 576 | 0.000 | 0.2 |
| Broiler-breeder | 14 | 2,718 | 8.5 | 4,002 | 824 | 0.001 | 0.4 |
| Meat-turkey | 30 | 469 | 3.7 | 3,208 | 1,042 | 0.017 | 11.7 |
| Turkey-breeder | 2 | 18 | 5.7 | 2,035 | 659 | 0.019 | 13.1 |
| Meat-duck | 16 | 267 | 1.2 | 3,477 | 1,180 | 0.050 | 33.9 |
| Duck-breeder | 14 | 70 | 5.8 | 4,107 | 767 | 0.034 | 23.4 |
*LPAIV, low pathogenicity avian influenza virus; RR, relative risk. †Distance to clay soil and distance to small- and large-sized waterways also included in the multivariate analysis (data not shown). They did not have a significant effect on the risk for LPAIV introduction. Waterway sizes were defined as follows: small, 0.5–3 m wide; medium, 3–6 m wide; large, >6 m wide. ‡Unadjusted probabilities of LPAIV introduction per farm months at risk. §These are the unadjusted RR estimates obtained by dividing the unadjusted probabilities of LPAIV introduction of each type of poultry farm by that of indoor-layer farms.