Table 3.

Univariate analyses of risk factors related to Babesia microti infection

Variable		Sample size		Babesia microti infection
		Cases	Constituent ratio (%)	Positive rate (%)	χ2	P-value
Year	2014	446	32.1	10.8	1.78	0.410
	2017	419	30.1	11.7
	2018	526	37.8	13.5
Altitude (m)	≤ 40	305	21.9	5.9	16.47	< 0.001
	40–400	903	64.9	14.5
	> 400	183	13.2	10.4
Gender	Female	514	39.4	9.9	4.77	0.029
	Male	790	60.6	14.2
Age	Adult	1149	82.6	13.3	8.88	0.003
	Pubertal	242	17.4	6.2
Ecological habitat	Residential	822	59.1	7.2	73.34	0.000
	Shrub	135	9.7	27.4
	Mixed forest	143	10.3	8.40
	Broad-leaved forest	191	13.7	23.00
	Cropland	100	7.2	16.00

This table shows that significant differences were related to different altitudes, genders, ages, and types of ecological habitat of the small mammals, but not to different sampling years, based on the univariate analyses using Chi-square test