Table 5.
Distribution of serological variables and estimated odds ratios for the effects of bovine respiratory syncytial virus (BRSV) and bovine parainfluenza virus 3 (BPIV-3) 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)f | Adjusted odds ratio (95% credible interval) |
|---|---|---|---|---|---|
| BRSV inductionb | |||||
| 0 | 919 | 397 (10.8) | 522 (14.3) | 11.4 (10.5–12.3) | Ref. cat. |
| 1 | 1719 | 829 (22.6) | 890 (24.4) | 22.9 (21.8–24.1) | 0.8 (0.6–1.0) |
| 2 or 3 | 3487 | 1820 (49.7) | 1667 (45.7) | 49.0 (47.7–50.4) | 0.7 (0.6–0.8) |
| 4 or 5 | 1189 | 617 (16.8) | 572 (15.7) | 16.7 (15.6–17.7) | 0.8 (0.6–1.0) |
| BRSV induction serostatusb | |||||
| Negative | 919 | 397 (10.8) | 522 (14.3) | 11.4 (10.5–12.3) | Ref. cat. |
| Positive | 6395 | 3266 (89.2) | 3129 (85.7) | 88.6 (87.7–89.5) | 0.8 (0.6–0.9) |
| BRSV compositec | |||||
| No change | 3650 | 1920 (55.1) | 1730 (49.2) | 54.2 (52.7–55.6) | Ref. cat. |
| Seroincrease | 2212 | 977 (28.0) | 1235 (35.1) | 29.2 (27.9–30.5) | 1.5 (1.3–1.7) |
| Initially high | 1139 | 587 (16.9) | 552 (15.7) | 16.7 (15.6–17.7) | 1.2 (1.0–1.5) |
| BRSV seroconversiond | |||||
| No | 282 | 146 (36.8) | 136 (26.0) | 35.1 (31.0–39.1) | Ref. cat. |
| Yes | 637 | 251 (63.2) | 386 (74.0) | 64.9 (60.9–69.0) | 1.5 (0.9–2.2) |
| BPIV-3 inductionb | |||||
| 0 | 713 | 311 (8.5) | 402 (11.0) | 8.9 (8.1–9.7) | Ref. cat. |
| 1 | 1114 | 557 (15.2) | 557 (15.3) | 15.2 (14.2–16.2) | 0.6 (0.5–0.8) |
| 2 or 3 | 3525 | 1769 (48.3) | 1756 (48.1) | 48.3 (46.9–49.6) | 0.6 (0.5–0.7) |
| 4 or 5 | 1962 | 1026 (28.1) | 936 (25.6) | 27.6 (26.4–28.9) | 0.6 (0.5–0.8) |
| BPIV-3 induction serostatusb | |||||
| Negative | 713 | 311 (8.5) | 402 (11.0) | 8.9 (8.1–9.7) | Ref. cat. |
| Positive | 6601 | 3352 (91.5) | 3249 (89.0) | 91.1 (90.3–91.9) | 0.6 (0.5–0.7) |
| BPIV-3 compositec | |||||
| No change | 3798 | 1982 (57.9) | 1816 (51.6) | 56.0 (54.6–57.5) | Ref. cat. |
| Seroincrease | 1352 | 545 (15.6) | 807 (23.0) | 16.8 (15.8–17.8) | 1.4 (1.1–1.6) |
| Initially high | 1851 | 957 (27.5) | 894 (25.4) | 27.1 (25.9–28.4) | 1.1 (0.9–1.2) |
| BPIV-3 seroconversione | |||||
| No | 278 | 151 (48.6) | 127 (31.6) | 45.8 (41.1–50.6) | Ref. cat. |
| Yes | 435 | 160 (51.4) | 275 (68.4) | 54.2 (49.4–58.9) | 1.5 (0.9–2.2) |
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 = 7314.
Covariates: mixing summary, test batch, selection batch, cohort size, shared pen water; N = 6997.
Covariates: mixing summary, cohort size, shared pen water; N = 919.
Covariates: mixing summary, cohort size, shared pen water; N = 713.
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).