| Cases/pig days | Incidence rate ratio | 95% Confidence Interval | Std. Err | p value | |
---|---|---|---|---|---|---|
Baseline incidence rate (constant) |  | 0.06 | 0.03 | 0.11 | 0.02 | 5.5e−22 |
Producer | ||||||
 Producer A | 12/415 | 1.00 (base) |  | |||
 Producer B | 18/385 | 3.78 | 1.85 | 12.83 | 2.41 | 0.001 |
Virulence factors | ||||||
 H+, F+T+ | 17/209 | 1.00 (base) |  |  |  |  |
 H+, F−, T+ | 1/5 | 1.87 | 0.25 | 14.24 | 1.94 | 0.544 |
 H+, F+, T− | 11/150 | 0.25 | 0.09 | 0.68 | 0.13 | 0.007 |
 H+, F−, T− | 2/48 | 0.10 | 0.033 | 0.01 | 0.11 | 0.033 |
 H− | 0/361 | NAa |  |  |  |  |