Background
Insecticide-treated bed nets (ITNs) are a cornerstone of malaria control in sub-Saharan Africa [
1,
2]. The World Health Organization (WHO) recommends universal access to, and use of long-lasting insecticidal nets (LLINs) for all individuals at risk of malaria so as to optimize ITN effectiveness [
3]. ITNs act by placing a physical barrier between the mosquito and humans and through the repellent toxic effects of the ITN-impregnated insecticides. ITNs have been shown to reduce malaria burden at both individual and community level leading to decreased morbidity, mortality and overall transmission potential [
1,
4,
5]. With ITNs also shown to be the most cost-effective intervention in reducing malaria transmission [
6], universal long-lasting insecticidal net coverage (ULC) has been recommended and is now widely implemented as a key intervention in malaria control efforts [
7].
The impact of LLIN scale-up on reducing malaria burden has been observed in Rwanda [
8]. With financial support mainly from The Global Fund to Fight AIDS, Tuberculosis and Malaria and the President’s Malaria Initiative, Rwanda achieved ULC—defined as a reported household ownership of at least one bed net per two individuals, as early as February 2011 [
9]. However, despite the observed initial decline in health facility-recorded malaria cases and deaths following LLIN scale-up in Rwanda, increases in malaria burden continue to be reported [
8,
10,
11]. While the resurgence in 2009 was mainly attributed to a reduced effectiveness of LLINs due to delays in provision of new nets at a time when the effectiveness of the previously provided LLINs was waning [
10], later resurgence may have been partly associated with the reported deployment of bed nets with sub-optimal concentrations of insecticide [
11]. However, although the reasons for the resurgence were not systematically characterized, continued scale-up and use of LLINs is needed if gains made in malaria burden decline in the past are to be sustained [
10]. To achieve and maintain ULC, Rwanda adopted the WHO’s recommendations for high malaria burden countries of using multiple distribution channels, including free ULCs that are supplemented by continuous LLIN distributions through programmes such as antenatal care (ANC) and immunization services for pregnant women and infants, respectively [
3,
9].
A key determinant of ITN impact is bed net use, with previous studies showing disparities between bed net ownership and use [
12‐
17]. One such determinant of bed net use is seasonality. While higher net use has been reported more in the rainy season due to the associated high mosquito density, lower net use has been associated with hot dry months due to heat-related discomfort [
12‐
14]. Other previously reported determinants of net use include number of nets owned per household, sex: with women more likely to use nets [
15], age [
15], head of household (HoH) education levels, disruptive sleeping arrangements [
16], and net misuse such as bed nets being used for activities in agriculture and fishing [
17]. Hitherto, studies on bed net use have mostly focused on children <5 years and pregnant women, two groups preferentially targeted for net coverage in the past because of their high malaria risk. There is limited and inconclusive data on ITN effectiveness under routine field settings after ULC targeting of all age and gender groups. Understanding these household-level bed net use patterns is needed to inform malaria control programmes on how to optimize bed net public health impact. Here, a community-based evaluation of bed net source, ownership and determinants of use was conducted 8 months after ULC.
Discussion
This study demonstrated a 92 % household ownership with at least one net and a 72 % bed nets use among 1400 households visited. Particularly among men, and in households of the low SES group with ≥two sleeping places, where individuals reported not sleeping on a bed, with a reported ownership of only one bed net, lower odds of net use were observed. Also, higher odds of net use with increasing number of nets in household were observed.
Comparable to the 92 % household bed net ownership in this study, high coverage rates have been reported elsewhere following UCL, including Sierra Leone (87.6 %), Togo (96.7 %) and Ethiopia (91.0 %) [
24‐
26]. Similarly as shown in this study, bed net use in these three settings was lower than bed net coverage, varying from 65.0 % in Ethiopia to 68.3 % in Togo and 76.5 % in Sierra Leone. This finding highlights a major need to supplement ULC with appropriate effective strategies that promote bed net use.
As observed in this study, previous studies have shown that females were more likely to use bed nets relative to males [
27‐
29]. A possible reason for the sex disparity in net use could be the traditionally high focus on promoting net use among females through health centres and ANC-based campaigns to target reduction of malaria risk for vulnerable pregnant women. This focus may have spilled over into higher rates of net use among females even in settings of ULC and in spite of the observed lower likelihood of net use amongst men. However, the specific reasons for low rates of net use among men were not explored in this study. Characterizing these reasons is key to identifying implementation gaps and targeting strategies towards promoting net use specifically among men.
In this study, individuals who reported not to have slept on a bed had lower odds of net use compared to those who slept on beds. In one study in Kenya conducted before and after a ULC, lower odds by 0.24 and 0.31-fold decrease among individuals who reported sleeping on the floor compared to those who slept on a bed was observed [
30]. In this same study, sleeping on the floor was almost fully associated with not using a net [
30]. Possible reasons for lower compliance to bed net use among those not sleeping on a bed range from practical house structural challenges, including difficulty in spreading a net over a sleeping material or a mattress, lack of a suitable structure for net hanging and disruptive sleeping arrangements that complicate ease of bed net use [
16,
31]. Although not studied here, it is plausible that bed net use is particularly difficult among those who did not sleep on a bed as the sleeping spaces are generally larger, irregular and much further from the point of net hanging and hence less amenable to feasible bed net use. In this study, 93 % of the houses visited had no ceiling, structures onto which nets are usually hung. It is plausible that lack of a place to hang or a need to improvise, such as by tying a long string from wall to wall onto which a net can be secured and as well as difficulty in securing net around floor-based sleeping arrangements, are some reasons for reduced likelihood of bed net use. Bed net hanging increases likelihood of bed net use [
32]. Further characterization of feasibility of bed net hanging and convenience of net use among those who do not sleep on a bed is needed to promote bed net use in this group. .
Households with ≥two sleeping spaces were associated with lower odds of net use. Given the bed net to household ratio of almost 2:1 (2769 bed nets for 1410 households) in the study area, it is likely, although not specifically assessed in this study, that households with more sleeping places did not have enough bed nets to cover each sleeping space. In this study, a progressive increase in odds of net use proportional to number of used nets the night before the survey was observed. Comparable findings to this study have been reported elsewhere. In Ethiopia, a household level net density of >one net per two people was associated with a fivefold (in 2006) and a twofold (in 2007) higher net use when compared to households with net densities of <one net per two persons [
32]. In Sierra Leone, a ULC was associated with a 137 % increase in bed net use within 6 months [
24]. In Uganda, following a ULC, LLIN availability was the only determinant of bed net use [
31]. This is plausible in this study area where there is a discrepancy between mean of household members size (4.7) and mean number of available nets (2.1), which is lower than the target of having one net per two household occupants. Therefore, since a greater intra-household access to an ITN is a strong determinant of net use, efforts to increase access to enough bed nets, particularly in households with many members, is required. To further increase net use among all age and gender sub-groups, net distribution campaigns should target coverage of at least of all sleeping spaces and ideally coverage of two nets per three persons or even one net per person.
Medium and high SES group households were associated with higher odds of bed net use in this study. Similar to findings in this study, higher net use amongst households with higher SES has been reported previously in Uganda [
33], and in Ethiopia [
34]. A possible reason for this observation may be that individuals from medium and high SES households have better information on access and capacity to buy supplementary LLINs and hence are more likely to use bed nets. Interestingly, associations between household SES and net use have been reported with mixed outcomes. In a smaller, prospective, hospital-based study in Nigeria, household SES did not influence bed net use [
35]. In contrast, Auta et al. in a study based on data extracted from a demographic and health survey exercise in Nigeria found higher rates of net use among individuals from the lowest wealth quintile [
36]. In the latter study, higher rates of net used was associated partly with a higher perception of malaria risk in the poorest settings that may have arisen from more concerted public health campaigns conducted in the area [
36]. On the contrary, higher SES group households may have greater access to more nets or more favourable factors that enhance adherence to net use.
The methodology employed and study findings had major strengths. Interviewer-spot checks in assessing bed net ownership, integrity and brand as well as verifying house structural feature characteristics limited potential recall and socio-desirability bias. In addition, both the interview questions used that were adapted from the standardized MIS and DHS tools and the quantitative analysis employed served to optimize study accuracy. This study evaluated for a key outcome of bed net use in a setting of high net coverage and hence provided rich data on the effectiveness of a UCL in a real community setting. The methodology used in this study had some limitations. Firstly, the decision to replace the 35 non-enrolled houses randomly selected households with nearest neighbour households may have had an effect on representativeness of the study findings. This most likely did no affect accuracy of study findings given that the proportion of replaced households was <2.5 % of total sample size. Secondly, this being a cross-sectional survey, study findings may be confounded by unmeasured factors, not be suitable for drawing causal inferences, and not be appropriate for showing how net ownership and use may vary over time. A possible social desirability bias of over-reporting may also have influenced rates of reported net ownership and use. In addition, the study area has had many bed net campaigns that may have positively influenced knowledge and attitudes on malaria prevention and in particular, led to higher rates of net use. Study findings may not be representative of low malaria endemic settings with low bed net coverage and limited awareness of bed net use. Given that this survey covered a relatively limited area, findings may not be generalizable to the entire country and more so in settings when ULC were not conducted.
Conclusion
Bed net ownership of ≥one net among households visited and a reported individual use among households members of 92 and 72 % was observed in the study area. This study confirmed that males in general and individuals from households of low SES, with one or more nets, where ≥two sleeping spaces are used, and those who slept on the floor relative to those who used beds, were less likely to use a net. Supplementary to LLIN scale-up campaigns, strategies to promote bed net use, particularly among males and houses with structural features that prevent mosquito entry and those that adapt bed net feasibility towards ease of use in groups such as those who do not sleep on a bed, are needed. Also, further studies on feasibility and cost-effectiveness research of ULC, as well as in-depth anthropological studies characterizing bed net use patterns, including reasons for lower net use among males, perceptions on bed net hanging, net characteristics that may lead to reduced bed net use, such as dirtiness, smells, shape, and colour and challenges of net use among those do not sleep on beds, would provide rich contextual data to inform future strategies aimed at improved net use.
Authors’ contributions
FK conceived the study, supervised the fieldwork, analysed the data and drafted the manuscript. CMI was involved in study conception and study implementation. EH and AL were both involved in developing study tools, training field interviewers and study implementation. MPG provided guidance on the manuscript draft. LM was involved in study implementation and critically reviewed draft manuscript. MvV was involved in study conception and provided input on draft manuscript preparation. PFM prepared data collection tools, provided guidance on data analysis and interpretation and substantially revised the manuscript. All authors read and approved the final manuscript.