Effects of indoor residual spraying and outdoor larval control on Anopheles coluzzii from São Tomé and Príncipe, two islands with pre-eliminated malaria

Table 3 Results of negative binomial regression model (no. of observations = 588)

Covariates	Estimate	Std. error	p value	Risk ratio (95% CI)
Urban area^a (AG, MZ, LO, CT)	2.443	0.373	< 0.001	11.50 (5.54–23.89)
Rural area^a (LE, CU)	2.233	0.378	< 0.001	9.33 (4.44–19.58)
Incidence rate (%) in previous month	2.796	0.152	< 0.001	16.39 (12.17–22.07)
Rainfall amount (100 mm) in previous month	0.225	0.052	< 0.001	1.25 (1.13–1.39)
Indoor EIR^b (%)	− 0.217	0.194	0.263	0.80 (0.55–1.18)
Outdoor EIR^c (%)	0.072	0.016	< 0.001	1.07 (1.04–1.11)
Kdr mutation frequency^d (10%)	0.060	0.019	0.0017	1.06 (1.02–1.10)

The response variable is monthly incidence rate in 7 districts from 2010 to 2016
^aReference area is the offshore island-Príncipe
^bIndoor EIR (%) is calculated by monthly mosquito density of indoor HLCs multiplied sporozoite rate (0.5%) which is referred from Pinto et al. [4]
^cOutdoor EIR (%) is calculated by monthly mosquito density of outdoor HLCs multiplied sporozoite rate (0.5%) which is referred from Pinto et al. [4]
^dKdr mutation frequency is calculated per season using Genepop ver 4.2. Kdr mutation frequency is assumed the same per month in the same season. The risk ratio is modelled by an increase of 10% in kdr mutation frequency

ISSN: 1475-2875