A prospective case–control and molecular epidemiological study of human cases of Shiga toxin-producing Escherichia coli in New Zealand

Table 1 Multivariate logistic regression model showing risk factors for sporadic cases of STEC infections in New Zealand

Variable	Coefficient (SE)^a	Adjusted odds ratio (95% CI)^b	p-value^c
Other household member having contact with animals other than household pets^d*
for 0–4 year-old	1.39 (0.42)	4.03 (1.78–9.13)	0.001
for 5–19 year-old	-0.77 (0.67)	0.47 (0.13–1.72)	0.251
for >19 year-old	0.30 (0.49)	1.35 (0.51–3.56)	0.541
Cattle livestock present in meshblock	0.64 (0.30)	1.89 (1.04–3.42)	0.037
Contact with animal manure	0.74 (0.32)	2.09 (1.12–3.90)	0.021
Contact with recreational waters	1.08 (0.42)	2.95 (1.30–6.70)	0.010
Travelled to areas in New Zealand with interrupted or no main water supply	0.89 (0.43)	2.43 (1.04–5.65)	0.040
Handling raw offal	-0.94 (0.35)	0.39 (0.20–0.78)	0.008
Drinking refrigerated fruit juice from supermarket	-1.37 (0.32)	0.25 (0.14–0.47)	<0.001
Visiting childcare/kindergarten/or school	-0.92 (0.31)	0.40 (0.22–0.73)	0.003
Eating raw vegetables	-0.65 (0.33)	0.52 (0.27–0.99)	0.046
Eating seafood	-0.52 (0.27)	0.59 (0.35–1.02)	0.057
Dining outside home	-0.44 (0.29)	0.65 (0.37–1.14)	0.133
Water supply to home from private bore/spring/creek/or stream	0.62 (0.39)	1.85 (0.86–4.00)	0.117
Contact with children wearing nappies	-0.33 (0.31)	0.72 (0.39–1.33)	0.298
Taking antacids	-0.84 (0.58)	0.43 (0.14–1.34)	0.147

Likelihood ratio test = 153.70 (df = 18, p < 0.001).
^aStandard error.
^b95% confidence interval.
^c p-values were computed based on 50 imputations.
^dThis variable was modelled using a multiplicative interaction term comprising the variables 'Other household member having contact with animals other than household pets’ and 'Age’.
It can be interpreted as follows: a child 0–4 years of age is at significantly higher risk of being an STEC case, if another household member had contact with animals other than household pets, compared to a child of the same age without this risk factor.
*p-value = 0.064 for the variable 'Other household member having contact with animals other than household pets’ without the interaction term.

ISSN: 1471-2334