Table 3.
Distribution of serological variables and estimated odds ratios for the effects of bovine herpesvirus 1 (BoHV-1) serological variables on the odds of being a BRD casea.
| Variable & category | Number of animals | Number (%) of controls | Number (%) of cases | Pooled weighted % (95% CI)i | Adjusted odds ratio (95% credible interval) |
|---|---|---|---|---|---|
| BoHV-1 inductionb | |||||
| 0 | 5681 | 2760 (75.5) | 2921 (80.0) | 76.2 (75.0–77.4) | Ref. cat. |
| 1 | 906 | 447 (12.2) | 459 (12.6) | 12.3 (11.4–13.2) | 1.0 (0.8–1.2) |
| 2 or 3 | 606 | 379 (10.4) | 227 (6.2) | 9.7 (8.9–10.5) | 0.7 (0.6–0.9) |
| 4 or 5 | 113 | 69 (1.9) | 44 (1.2) | 1.8 (1.4–2.2) | 1.0 (0.5–1.6) |
| BoHV-1 induction serostatusb | |||||
| Negative | 5681 | 2760 (75.5) | 2921 (80.0) | 76.2 (75.0–77.4) | Ref. cat. |
| Positive | 1625 | 895 (24.5) | 730 (20.0) | 23.7 (22.6–25.0) | 0.9 (0.7–1.0) |
| BoHV-1 compositec | |||||
| No change | 3101 | 1847 (53.1) | 1254 (35.7) | 50.2 (48.8–51.7) | Ref. cat. |
| Seroincrease | 3805 | 1581 (45.4) | 2224 (63.2) | 48.2 (46.8–49.6) | 1.4 (1.2–1.6) |
| Initially high | 95 | 56 (1.6) | 39 (1.1) | 1.5 (1.2–1.9) | 1.5 (0.8–2.5) |
| BoHV-1 seroconversiond | |||||
| No | 2267 | 1332 (48.3) | 935 (32.0) | 45.7 (44.1–47.3) | Ref. cat. |
| Yes | 3414 | 1428 (51.7) | 1986 (68.0) | 54.3 (52.7–55.9) | 1.3 (1.1–1.5) |
| Vaccinated with Rhinogard® | |||||
| BoHV-1 seroconversione | |||||
| No | 1742 | 852 (40.6) | 890 (31.1) | 39.1 (37.3–40.8) | Ref. cat. |
| Yes | 3217 | 1248 (59.4) | 1969 (68.9) | 60.9 (59.2–62.7) | 1.3 (1.1–1.6) |
| Not vaccinated with Rhinogard® | |||||
| BoHV-1 induction serostatusf | |||||
| Negative | 484 | 458 (75.5) | 26 (89.7) | 77.7 (74.3–81.1) | Ref. cat. |
| Positive | 152 | 149 (24.5) | 3 (10.3) | 22.3 (18.9–25.7) | 0.7 (0.1–2.1) |
| BoHV-1 compositeg | |||||
| No change | 475 | 459 (79.1) | 16 (59.3) | 76.0 (71.9–80.0) | Ref. cat. |
| Seroincrease | 122 | 111 (19.1) | 11 (40.7) | 22.6 (18.6–26.6) | 1.4 (0.4–3.4) |
| Initially high | 10 | 10 (1.7) | 0 (0.0) | 1.5 (0.6–2.3) | excluded |
| BoHV-1 seroconversionh | |||||
| No | 368 | 353 (77.1) | 15 (57.7) | 74.0 (69.5–78.4) | Ref. cat. |
| Yes | 116 | 105 (22.9) | 11 (42.3) | 26.0 (21.6–30.5) | 1.3 (0.3–3.4) |
Models fitted using three-level mixed effects logistic regression; N: number of observations in model; this may differ from the numbers in the descriptive results because of missing values for covariates.
Covariates: mixing summary, test batch, selection batch; N = 7302.
Covariates: mixing summary, test batch, selection batch, cohort size, Rhinogard, shared pen water; N = 6997.
Covariates: mixing summary, cohort size, Rhinogard, shared pen water; N = 2841.
Covariates: mixing summary, cohort size, shared pen water; N = 4633.
Covariates: mixing summary; N = 636 animals sampled within 7 days of arrival.
Covariates: mixing summary, cohort size, shared pen water; N = 607 animals sampled within 7 days of arrival.
Covariates: mixing summary, cohort size, shared pen water; N = 484 animals sampled within 7 days of arrival.
Estimated seroprevalences and seroincidences for the NBRDI project population, the source population for the current case-control study; calculated as pooled weighted averages (0.84 × observed percentage in controls + 0.16 × observed percentage in cases) based on the ratio of the sampling fractions for selection from the NBRDI project population as a case versus as a control (5.3:1).