Table 2.

Impact of Targeted Indoor Residual Spraying With Pirimiphos-Methyl on Malaria Parasite Prevalence in the Entire Study Area, by Season (n = 3,311), Nchelenge District, Zambia, 2012–2017^a

Participant Characteristic	Season
	Rainy Season			Dry Season
	PRR	95% CI	P Value	PRR	95% CI	P Value
Post-IRS period (vs. pre-IRS period)	0.89	0.79, 1.01	0.07	0.91	0.80, 1.04	0.2
Male sex	1.17	1.07, 1.27	<0.001
Age <5 years	1.78	1.56, 2.03	<0.001	1.88	1.61, 2.20	<0.001
Age 5–16 years	2.16	1.92, 2.42	<0.001	2.32	2.02, 2.67	<0.001
Sleeping under a bed net	0.82	0.74, 0.91	<0.001	0.87	0.78, 0.97	0.01
HOH primary schooling only	1.13	1.00, 1.27	0.04	1.17	0.97, 1.29	0.1
No. of HHs within 500 m (per 100 HH)	0.92	0.90, 0.95	<0.001	0.95	0.92, 0.98	0.003
Elevation, m (per 10 m)	0.88	0.84, 0.92	<0.001	0.90	0.85, 0.95	<0.001
Distance from health clinics, km	1.06	1.03, 1.09	<0.001	1.07	1.02, 1.12	0.006
Distance from roads, m (per 100 m)	0.96	0.93, 0.98	0.001
Distance from category 3 streams, km				0.85	0.72, 1.01	0.07
Lagged rainfall, mm (per 10 mm)b	1.19	0.98, 1.44	0.08
Lagged minimum temperature, °Cc	1.09	1.03, 1.15	0.002
Lagged maximum temperature, °Cd				1.17	1.09, 1.17	<0.001
Lagged streamflow, m3/second (per 1,000 m3/second)e				0.90	0.83, 0.97	0.005

Abbreviations: CI, confidence interval; HH, household; HOH, head of household; IRS, indoor residual spraying; PRR, prevalence rate ratio.

^a Multivariate Poisson models using robust standard errors and with responses clustered by household using generalized estimating equations.

^b Lag = 1–5 weeks.

^c Lag = 2–5 weeks.

^d Lag = 3–8 weeks.

^e Lag = 4–6 weeks.