Proximity to vector breeding site and risk of Plasmodium vivax infection: a prospective cohort study in rural Ethiopia

Table 2 Cox regression models with adjusted rate ratios of P. vivax infection for various risk factor levels

	Model 1—no adjustments for ITN use fraction (n = 8121)		Model 2—adjusted for ITN use fraction (n = 8096)
	RR (95% CI)	P value	RR (95% CI)	P value
Increasing household proximity to breeding site^a	1.50 (1.30–1.74)	< 0.001	1.56 (1.34–1.81)	< 0.001
Age at study entry
≥ 25	Ref		Ref
15–24	1.73 (0.89–3.36)	0.11	1.40 (0.69–2.83)	0.35
5–14	4.71 (2.73–8.13)	< 0.001	3.54 (1.95–6.43)	< 0.001
0–4	6.49 (3.64–11.55)	< 0.001	5.47 (2.98–10.06)	< 0.001
Gender
Males	Ref		Ref
Females	0.85 (0.61–1.18)	0.34	0.86 (0.62–1.20)	0.38
Persons living in household
≤ 7	Ref		Ref
≥ 8	1.27 (0.92–1.77)	0.15	1.16 (0.83–1.63)	0.39
ITN use fraction (%)^b
> 50			Ref
≤ 50			1.85 (1.20–2.83)	0.005

^aDistance to breeding site was categorized into: > 2700 m (ref); 2400–2700; 2100–2400; and < 2100 m, and modelled linearly
^bITN use was recorded weekly (starting from week 5) during the regular follow-up visits to households. Participants were asked if they slept under a ITN the night before the visit. Use fraction was calculated as the number of nights reportedly sleeping under a ITN divided by the total number of nights asked. For those with P. vivax infection, ITN use fraction was calculated only for weeks prior to infection

ISSN: 1475-2875