Table 1.
Significant factors, in logistic regression models, associated with B. burgdorferi infection in ticks collected in passive surveillance.
| Explanatory variable | No. positive/no. tested (%)a | OR (95% CI) | p-Value |
|---|---|---|---|
| Model A | |||
| Ticks submitted from outside space–time cluster | 273/2,139 (12.9) | Reference | |
| Ticks submitted from within cluster | 57/1,083 (4.9) | 0.38 (0.29–0.52) | < 0.001 |
| Stage of engorgement | |||
| No engorgement | 15/253 (5.9) | Reference | |
| Semiengorged | 250/2,394 (10.4) | 1.77 (1.03–3.04) | 0.038 |
| Fully engorged | 63/541 (11.6) | 1.82 (1.01–3.27) | 0.024 |
| Model B | |||
| Ticks submitted from outside space–time cluster | 273/2,139 (12.9) | Reference | |
| Ticks submitted from within cluster | 57/1,083 (4.9) | 0.36 (0.27–0.49) | < 0.001 |
| Host | |||
| Human | 15/280 (5.3) | Reference | |
| Dog | 193/2,044 (9.4) | 1.85 (1.08–3.20) | 0.020 |
| Cat | 122/892 (13.7) | 3.01 (1.72–5.26) | < 0.001 |
Abbreviations: CI, confidence interval; OR, odds ratio. Two models are presented because stage of engorgement and host of origin of ticks were collinear.
a
Data on host or state of engorgement were missing from 20 ticks, so numbers of tested ticks are not identical for each variable.