TABLE 3.

Univariate Risk-Factor Analysis for Shigellosis

Risk Factor	IR	95% CI	P
			Overall	vs Referencea
Child’s gender
Female	0.35	0.29–0.41	.5849	Same
Male	0.33	0.28–0.38
Maternal age, y
≤19	0.27	0.19–0.38	.2549	.1123
20–24	0.39	0.31–0.47		.7719
25–29	0.33	0.25–0.41		.5724
30–34	0.32	0.24–0.41		.4574
≥35	0.37	0.28–0.47		Reference
Child <2 y younger than sentinel in household
0
≥1
Maternal education
Incomplete primary (<6 y)	0.35	0.31–0.40	.4928	Same
Primary school or greater	0.32	0.24–0.41
Crowding: people per m2 in home
Minimum–Q25 (0.00 to 0.08)	0.31	0.24–0.40	.7015	.4342
Q25–Q75 (0.08 to 0.18)	0.35	0.29–0.41		.8705
Q75–maximum (0.18 to 2.25)	0.36	0.29–0.44		Reference
Monthly income per capitab
Minimum–Q25 (0 to 35)	0.42	0.35–0.52	.0135	Reference
Q25–Q75 (36 to 100)	0.34	0.29–0.40		.1094
Q75–maximum (101 to 350)	0.26	0.20–0.34		.0031
Floor material
Dirt	0.37	0.32–0.42	.0027	.7627
Cement	0.23	0.17–0.30		.0446
Wood, bark	0.40	0.25–0.64		Reference
Drinking water source
Piped water to household	0.32	0.28–0.37	.1602	.0002
Piped water from public tap	0.29	0.20–0.42		.0011
Well	0.39	0.30–0.49		.0096
River or inlet	0.70	0.48–1.03		Reference
Volume of smallest water container, L
0 (no storage)	0.37	0.21–0.66	.9662	.7479
1–5	0.36	0.28–0.47		.6499
6–19	0.34	0.24–0.48		.9319
≥20	0.34	0.29–0.39		Reference
Water storage per person, L
No storage	0.32	0.15–0.67	.4281	.9196
Minimum–Q25 (0.8 to 9.5)	0.41	0.27–0.38		.1076
Q25–Q75 (10 to 25)	0.33	0.32–0.50		.6896
Q75-maximum (>25)	0.31	0.24–0.38		Reference
Water storage (L) per person with sealed tops
No sealed storage	0.44	0.35–0.54	.0872	.0126
Minimum–Q25 (<4)	0.33	0.24–0.45		.4987
Q25–Q75 (4.0 to 11.5)	0.32	0.26–0.37		.5723
Q75–maximum (≥12)	0.29	0.21–0.37		Reference
Distance, water source to kitchen, m
0.0–1.5	0.33	0.26–0.41	.1250	.1373
2.0–3.5	0.28	0.23–0.35		.0145
4.0–9.5	0.37	0.29–0.47		.3244
≥ 10.0	0.41	0.33–0.51		Reference
Type of latrine
Family bathroom (inside home)	0.20	0.07–0.52	.1247	.2248
Family latrine (outside home)	0.36	0.31–0.40		.9478
Shared latrine	0.28	0.21–0.36		.1279
Well, river, or field	0.36	0.26–0.48		Reference
Sewers in/around household covered
Yes	0.22	0.14–0.34	.0397	Same
No	0.36	0.32–0.40
Birth weight
<2.5 kg	0.39	0.26–0.58	.4864	Same
≥2.5 kg	0.34	0.30–0.38
Anthropometrics, HAZ
Minimum–Q25 (−5.68 to 2.32)	0.41	0.33–0.52	.2462	.0939
Q25–Q75 (−2.32 to 1.14)	0.32	0.27–0.38		.7321
Q75–maximum (−1.1 to4.44)	0.30	0.24–0.38		Reference
Anthropometrics, WAZ
Minimum–Q25 (−3.91 to 1.38)	0.39	0.30–0.49	.0032	.0033
Q25–Q75 (−1.38 to 0.16)	0.37	0.31–0.43		.0062
Q75–maximum (−0.16 to4.77)	0.22	0.17–0.29		Reference
Anthropometrics, WHZ
Minimum–Q25 (−3.18 to 0.1)	0.37	0.29–0.46	.0050	.0098
Q25–Q75 (−0.1 to 0.91)	0.38	0.32–0.44		.0045
Q75–maximum (0.91 to 5.78)	0.23	0.18–0.30		Reference
Breastfeeding Status (children enrolled at <9mo age)
Exclusive	0.16	0.06–0.41	.1270	.1131
Mostly exclusive	0.16	0.03–0.89		.3914
Partial breastfeeding	0.31	0.21–0.45		.5281
Weaned
Breastfeeding status (all children)
Exclusive	0.35	0.28–0.43		Reference
Mostly exclusive	0.25	0.14–0.49	.4728	.3876
Partial breastfeeding	0.16	0.03–0.89		.3997
Weaned	0.35	0.25–0.48		.9620
Exclusive	0.35	0.30–0.39		Reference
Season
November–March, all years	0.21	0.16–0.26	<0001	Reference
March–October, 2003	0.56	0.46–0.68		<.0001
March–October, 2004	0.44	0.34–0.55		<.0001
March–October, 2005	0.29	0.22–0.38		.0783
March–October, all years	0.46	0.40–0.53		<.0001

^aOverall P values comparing >2 groups reflect differences among any of the groups. P values “vs Reference” reflects the comparison of each group (row) relative to the group (row) labeled as the reference group.

^bIn Peruvian nuevo soles, 1 US dollars = 3.5 Peruvian soles at the time of the study.