Table 5. Negative binomial regression models of Ascaris and hookworm reinfection intensity in Panamanian preschool children.

	Ascaris	Ascaris	Hookworm
	Cycle 1	Cycle 2	Cycle 2
	9 mo	6 mo	6 mo
	IRR1	IRR	IRR
Regional Factors
In High Cluster, baseline Cycle 22	NA3	NA	NE
Household Factors
Household density, homes/km 2	NE4	0.96 (0.93–1.001)	NE
Household wealth, HWI	0.19 (0.08–0.48)**	145 (7–3012)*	NE
Mother's education, yrs	NE	0.48 (0.28–0.80)*	NE
Individual Factors
Age, mo	NE	0.93 (0.88–0.99)*	NE
Sex5	NE	27 (2–303)*	NE
Baseline Infection, epg	1.0001 (1.0000–1.0002)**	1.0003 (1.0001–1.0006)*	1.004 (1.00–1.009)
Height-for-Age, Z score	0.15 (0.07–0.32)**	NE	0.49 (0.29–0.84)*
Latrine use6	0.007 (0.001–0.04)**	0.0001 (0–0.05)*	NE
Model Statistics
N	100	140	140
P	<0.001	<0.001	<0.001
Wald chi2	104.74	55.95	10.49
1/Alpha7	0.04(0.02–0.06)	0.01 (0.007–0.02)	0.02 (0.01–0.04)

¹Incidence Rate Ratio.

²Household within identified high prevalence cluster of infection by SaTScan Spatial Scan (0 = no, 1 = yes).

³NA = Not applicable.

⁴NE = Variable was excluded during the stepwise process (p>0.10).

⁵0 = boy, 1 = girl.

⁶0 = no, 1 = yes.

⁷1/Alpha statistic indicates the degree of overdispersion in the data.

^*p<0.05,

^**p<0.001.

Variables that did not enter any model: Household crowding.