Table 2.
Frequencies of clinical and demographic risk factors and their unconditional association with new infection with Leptospira interrogans serovar Pomona and/or Leptospira borgpetersenii serovar Hardjo in sheep abattoir workers (n = 384)
| Risk factor | Category | Workers, n (%) | New infection, % | Crude RR | 95% CI | P value |
|---|---|---|---|---|---|---|
| Confirmed clinical leptospirosis*† | No | 99·0 (380) | 11·9 | — | — | — |
| Yes | 1·0 (3) | 50·0 | ||||
| Had influenza-like illness*‡ | No | 73·4 (279) | 9·3 | — | — | — |
| Yes | 26·6 (101) | 20·8 | ||||
| Possible leptospirosis§ | No | 94·3 (362) | 0·0 | — | — | — |
| Yes | 5·7 (22) | 100·0 | ||||
| Gender | Female | 33·3 (128) | 7·8 | Ref. | ||
| Male | 66·7 (256) | 14·5 | 1·9 | (0·9–3·7) | 0·084 | |
| Age, years | ⩽40 | 25·8 (99) | 10·1 | Ref. | ||
| >40 to ⩽50 | 25·0 (96) | 9·4 | 0·9 | (0·4–2·3) | 0·871 | |
| >50 to ⩽57·5 | 24·2 (93) | 16·1 | 1·6 | (0·7–3·6) | 0·252 | |
| >57·5 | 25·0 (96) | 13·5 | 1·3 | (0·6–3·1) | 0·486 | |
| Ethnicity | NZ European | 42·7 (164) | 9·1 | Ref. | ||
| NZ Maori | 49·2 (189) | 14·8 | 1·6 | (0·9–3·0) | 0·132 | |
| Other | 8·1 (31) | 12·9 | 1·4 | (0·5–4·3) | 0·541 |
RR, Relative risk; CI, confidence interval.
*
Not included in the logistic regression model, as it was an intermediate variable between exposure and antibody level.
†
n = 383.
‡
n = 380.
§
Not included in the logistic regression model, as it includes the outcome.