Table 3.

Salivary antibody immunoconversions by sociodemographic factors and study phase, total number / incidence rate per 100 person-years with p values for trend using the exact two-sided Cochran-Armitage test for trend

Factor	Category	Cryptosporidium	p value for trend	GI norovirus	p value for trend	GII noroviruses	p value for trend
All		32 / 6.0	NA	125 / 23.3	NA	112 / 20.9	NA
Age, years	1–10	20 / 8.5		67 / 28.4		56 / 23.7
	11–20	5 / 5.6		28 / 31.5		20 / 22.5
	21–40	6 / 4.2		15 / 10.4		24 / 16.7
	41–85	1 / 1.5	0.03	15 / 22.4	0.01	12 / 17.9	0.2
Sex	Male	9 / 4.4		50 / 24.2		38 / 18.4
	Female	23 / 7.2	0.2	75 / 23.4	0.9	74 / 23.1	0.2
Study phase	1	17 / 8.2		51 / 24.5		33 / 15.8
	2	15 / 4.6	0.5	74 / 22.6	0.3	79 / 24.2	0.0005
Language spoken at home	English	10 / 8.1		32 / 25.8		40 / 32.2
	Any other	22 / 5.3	0.2	93 / 22.6	0.3	72 / 17.5	0.0005
Household income	Less than $ 25,000	21 / 6.2		82 / 24.0		71 / 20.8
	$ 25,000 or more	11 / 5.7	1.0	43 / 22.1	1.0	41 / 21.1	0.7
Highest education of adult household members	High school or less	22 / 7.1		88 / 28.3		70 / 22.5
	More than high school	10 / 4.4	0.3	37 / 16.5	0.007	42 / 18.7	0.4
Total household size, individuals	2–3	7 / 5.2		27 / 20.0		22 / 16.3
	4–5	17 / 6.2		49 / 17.8		59 / 21.4
	6–9	8 / 6.4	0.6	49 / 39.2	0.001	31 / 24.8	0.09
Home water filter present	No	16 / 6.5		62 / 25.2		58 / 23.6
	Yes	16 / 5.5	0.6	63 / 21.5	0.4	54 / 18.6	0.2