Table 1. Comparison of bivariate non-spatial models for S. japonicum infections based on either ELISA or Kato-Katz results with demographic, reservoir and environmental covariates that were significant at a p-value<0.15.

Covariate group	Covariate	Covariate category	ELISA			Kato-Katz
			ORa	CIb	AICc	ORa	CIb	AICc
Demography
	Age group (years)
		0–10	1			1
		11–20	2.06	1.68, 2.52		1.56	0.83, 2.95
		21–30	3.59	2.91, 4.43		4.41	2.36, 8.25
		31–40	4.42	3.65, 5.35		6.01	3.35, 10.76
		41–50	5.27	4.34, 6.38		8.32	4.65, 14.89
		>50	5.56	4.60, 6.73	33584	8.52	4.78, 15.19	8442
	Sex
		Female	1			1
		Male	1.99	1.88, 2.11	33914	3.12	2.66, 3.65	8474
	Occupation
		Herdsman, farmer, fisherman or boatman	1			1
		Preschool or student	0.33	0.30, 0.36		0.17	0.13, 0.23
		Civil servant or businessman	0.88	0.75, 1.04		0.22	0.11, 0.47
		Other	0.52	0.39, 0.71	33690	0.56	0.27, 1.13	8456
Reservoir
	Presence of infected buffaloes in the village		1.76	1.66, 1.86	34104	2.96	2.60, 3.40	8458
	Prevalence of infected buffaloes in the village		1.25	1.22, 1.28	34136	1.35	1.29, 1.41	8571
Environment
	Mean NDVI		1.20	1.16, 1.24	34337	0.98	0.92, 1.05	8706
	Mean NDVI during spring, summer and fall		1.31	1.26, 1.35	34204	1.16	1.07, 1.25	8691
	Mean NDVI during winter		1.08	1.05, 1.11	34439	0.86	0.81, 0.91	8682
	Distance to Dongting Lake (km)		1.08	1.05, 1.11	34438	1.05	0.99, 1.13	8703
	Endemic types
		Lake embankment	1			1
		Inside embankment	0.69	0.61, 0.78		0.24	0.17, 0.33
		Lake fork	1.02	0.94, 1.12		0.72	0.60, 0.85
		Grassy lake beach/marshland	0.78	0.70, 0.86		0.16	0.12, 0.21
		Hills/hilly area	0.52	0.45, 0.61	34292	0.02	0.01, 0.07	8324

^aOR: Odds ratio.

^bCI: Confidence interval.

^cAkaike information criterion. The smaller the AIC the better the model performance.