Increased proportions of outdoor feeding among residual malaria vector populations following increased use of insecticide-treated nets in rural Tanzania

Table 1 The proportion (bites per person per night) of mosquitoes caught indoors and during sleeping hours during 1997, 2004 and 2009.

Year	Proportion ± s.e.	n/N^{a, b}	Odds ratio [95% CI]	p value
*Endophagy* ^a
*Anopheles gambiae s.l*.
1997^c	0.585 ± 0.019	394/674	1.00	NA
2004	0.660 ± 0.006	3,916/5,931	1.113 [0.887 - 1.395]	0.354
2009	0.575 ± 0.008	2,390/4,160	0.970 [0.770 - 1.221]	0.796
Overall influence of Year		6,700/10,765	NA	0.248
*Anopheles funestus*
1997^c	0.608 ± 0.025	217/357	1.00	NA
2004	0.463 ± 0.055	38/82	0.726 [0.461 - 1.142]	0.166
2009	0.298 ± 0.027	86/288	0.455 [0.323 - 0.641]	<0.0001
Overall influence of Year		341/727	NA	0.0001
*Nocturnality* ^b
*Anopheles gambiae s.l*.
1997^c	0.957 ± 0.008	645/674	1.00	NA
2004	0.902 ± 0.004	5,347/5,931	0.942 [0.840 - 1.056]	0.305
2009	0.794 ± 0.006	3,303/4,160	0.829 [0.738 - 0.933]	0.0018
Overall influence of Year		9,295/10,765	NA	<0.0001
*Anopheles funestus*
1997^c	0.980 ± 0.007	350/357	1.00	NA
2004	0.829 ± 0.042	68/82	0.846 [0.594 - 1.208]	0.354
2009	0.704 ± 0.027	203/288	0.719 [0.570 - 0.907]	0.0054
Overall influence of Year		621/727	NA	0.0200

Proportions for each survey period are compared using GLMMs with a binomial distribution, a categorical explanatory variable for study year and a random factor for date.
^a Proportion of mosquitoes caught indoors calculated as: (I_{18→06 hrs})/(I_{18→06 hrs} + O_{18→06 hrs})
^b Proportion of mosquitoes caught during hours when most people are asleep calculated as: (I_{21→05 hrs} + O_{21→05 hrs})/(I_{18→06 hrs} + O_{18→06 hrs})
^c Formed the reference category for the GLMM

ISSN: 1475-2875