Background

Approximately two hundred million malaria cases were recorded in African region, accounting for 92% of the global malaria cases [1, 2]. Nearly 50% of all the global cases of malaria recorded in 2017 were accounted for by five countries: four of which were in sub-Saharan Africa with Nigeria contributing a quarter (25%) of the total cases, followed by Democratic Republic of Congo with 11%, Mozambique contributing 5%, and Uganda with 4% [1]. Though there was a reduction of 20 million malaria cases as estimated in 2017, the 10 malaria most burdened countries in Africa still reported an upsurge of the disease. Among these 10 highest burdened countries, Nigeria and Madagascar as well as Democratic Republic of Congo had the highest increase with each accounting for more than 500,000 cases [1].

In Nigeria, malaria remains a major public health problem, taking its greatest toll on pregnant women and children under age 5. About 60% of all health facilities outpatients’ visits are due to malaria [3]. Which also accounts for 30% and 25% of under-5 and infant mortality respectively [3]. Moreover, about 11% of maternal mortality is traceable to malaria cases [3]. The enormous financial resources expended in the control and treatment of malaria shows the negative economic impact that it has on households. Also, malaria has caused a significant drawback to the socioeconomic growth of many households and high disability adjusted life years (DALYs). The concerted efforts of vector surveillance approach, the wide distribution of long lasting insecticide-treated nets (LLINs) as well as the educational campaigns should bring a reduction in malaria burden among the endemic regions. LLINs, among several other interventions, have significantly contributed to the reduction of the global burden of malaria since the year 2000. Over the years, as LLINs success is being evaluated, modification in the treatment of nets have emerged. These modifications were due to the insecticide-resistance by the malaria vectors and have led to the development of pyrethroid-synergist piperonyl butoxide (PBO) nets which is being given an interim endorsement by World Health Organization (WHO), as a class of vector control products [4–6].

The PBO LLIN as well as the non-pyrethroid indoor residual spraying interventions have shown an improvement in the control of malaria transmission, when compared with the standard LLINs in the regions with high prevalence of pyrethroid resistance. These have led the WHO to recommend that PBO LLIN be increased [4, 6]. The combination of indoor residual spraying (IRS) using pirimiphos-methyl and PBO-LLINs could not provide any added advantage in comparison with PBO-LLINs alone or the standard LLINs and IRS. Though LLINs have been widely used by most people at risk of malaria, a great deal of communities is yet to maximize the available malaria control interventions in order to control the disease. There are ample evidence that some people in the malaria endemic regions do not have access to LLINs and therefore do not use it at all [5].

Malaria being one of the prominent causes of morbidity and mortality in resource-constrained settings, brought about the Roll Back Malaria Initiative (RBMI) which identified the use of LLIN as a key strategy for malaria prevention especially for women and under-5 children [7]. To minimize the socioeconomic impact that malaria brought in Nigeria, the Federal Ministry of Health and Roll Back Malaria partners adopted the Scale-Up for Impact (SUFI) approach enshrined in the revised edition of the National Malaria Strategic Plan (NMSP). The target of this approach was to increase the ownership of LLINs and its use among the key population [8]. The control of malaria vector has provided a preventive line of attack to the incidence of complications and deaths caused by the disease. Interestingly, the WHO is also using the combine duo approaches of IRS and LLINs to control malaria [9].

Furthermore, WHO has recommended the use of IPTp for malaria prevention during pregnancy [10]. The efforts to scale-up IPTp using Sulfadoxine-Pyrimethamine (SP) amongst others have been slow in some African countries. To aid this process, health workers have asked several questions around the administration and use of IPTp-SP especially that it must be taken as directly observed therapy. It was against this backdrop that WHO is expanding on her recommendations to national health authorities to publicize these recommendations to their citizens and enforce their correct application [10]. One of these recommendations is to protect pregnant women with SP antimalarial drug in regions where there are moderate and high transmission of malaria [11]. In Nigeria, only 26.2% of pregnant women took three doses or more of IPTp as recommended by the WHO [12].

Previous studies have identified geographical divisions as a key predictor in the uptake of LLIN, IPTp as well as other maternal health care interventions. For example, regional differences emerged as the most important predictor of insecticide-treated nets (ITN) ownership and use in Nigeria, according to a subnational profiling analysis [13]. In Tanzania, women’s geographical zones of residence was a significant predictor of IPTp uptake [14, 15]. In another previous study, being a resident of the Eastern Zone was linked to increased IPTp uptake when compared with the Lake Zone [14]. In Mali, geographical region was associated with IPTp uptake [16]. Another study reported that women from southern Mozambique were more likely to uptake IPTp when compared with those from the northern region [17].

In Nigeria, there is large peculiarity in health care-seeking behaviours across geographical regions. For example, women from the southern region comprising of south-south, south-east and south-west are believed to be more educated than their counterpart in the northern region (north-central, north-east and north-west) and therefore could be more likely to uptake health care services. Women’s education or enlightenment has been reported to be positively associated with health care services uptake [18–22]. Other geographical region-based factors such as ethnicity, cultural norms, religion amongst others could influence the uptake of IPTp and LLIN as practiced in the region. Despite the fact that huge distribution efforts regarding malaria prevention and control have been going on in Nigeria since over a decade, to the best of our knowledge, studies that examined the rate of consumption of such commodities, especially the regional patterns, are lacking in literature. In light of the above, this study aimed to examine the differentials in IPTp and LLINs uptake among women of reproductive age across the six geopolitical zones in Nigeria.

Methods

Definition of variables

Outcome variable.

Our outcome variables were IPTp and LLIN. These were measured dichotomously as yes vs. no if a woman used or did not use.

Explanatory variables.

The explanatory variables included in this study were selected based on previous studies [13–17, 23], and are presented in Table 1 below.

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Table 1. Categories and operational definition of independent variables.

https://doi.org/10.1371/journal.pone.0254475.t001

The MICS data had already developed and classified household wealth quintile as a variable into five groups, each of which was worth 20% of the total: poorest, poorer, middle, richer, and richest. We re-categorized household wealth quintiles into two categories for the analysis: poor (poorest, poorer) and non-poor (middle, richer and richest) [25, 26].

Results

Table 2 showed the pooled prevalence and differentials by geopolitical zones of IPTp in Nigeria. The overall prevalence of IPTp was 76.0% in Nigeria. Moreover, there were differences across geopolitical zones. The South South zone had the highest prevalence of IPTp (79.7%), followed by North West with 78.2%, North East (76.9%), South East (76.1%), South West (72.4%) and the least prevalence is the North Central zone with a prevalence of (71.3%). In addition, the prevalence were examined across respondents’ characteristics whereby the results showed within respondents characteristics and between geopolitical zones differentials respectively. The prevalence of IPTp was statistically different by women’s exposure to media, marital status, education, ethnicity and state of origin in north-central region (p<0.05). Furthermore, the prevalence of IPTp was statistically different by women’s media use, wealth status and state of origin in north-east region (p<0.05). In the north-west, IPTp prevalence was statistically different by women’s age, exposure to media use, residential status, wealth status and state of origin (p<0.05). IPTp prevalence was statistically different by women’s exposure to media, education, wealth status and the state of origin in south-east region (p<0.05). In addition, IPTp prevalence was statistically different by exposure to media, marital status, education, wealth status and state of origin in south-south region (p<0.05). In south-west region, the prevalence of IPTp was statistically different by women’s state of origin (p<0.05). Chi-square test was used to determine the statistical significance. Table 2 showed more details on this.

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Table 2. Distribution of intermittent preventive treatment in pregnancy in Nigeria.

https://doi.org/10.1371/journal.pone.0254475.t002

Results from Table 3 showed the pooled prevalence and differentials by geopolitical zones of LLINs utilization among women of reproductive age in Nigeria. The overall prevalence of LLIN was 87.7%% in Nigeria. Furthermore, there were changes across geopolitical zones. The North East zone had the highest prevalence of LLINs (91.8%), followed by North West with 90.0%, North Central (89.1%), South South (81.1%), South East (77.3%) and the least prevalence is the South West zone with a prevalence of (69.8%). In addition, the prevalence were examined across respondents’ characteristics whereby the results showed within respondents characteristics and between geopolitical zones differentials respectively. The prevalence of LLIN was statistically different by women’s age, residential status, ethnicity and state of origin in north-central region (p<0.05). Furthermore, the prevalence of LLIN was statistically different by women’s age, marital status and state of origin in north-east region (p<0.05). LLIN prevalence was statistically different by women’s exposure to media, marital status, ethnicity and state of origin in north-west region (p<0.05). In addition, LLIN prevalence was statistically different by women’s age, number of children ever born, marital status, education, wealth status and state of origin in south-east region (p<0.05). In south-south region, the prevalence of LLIN was statistically different by women’s age, media use, marital status, residential status, wealth status and state of origin (p<0.05). The prevalence of LLIN was statistically different by women’s age, number of children ever born, marital status and state of origin in south west (p<0.05). The statistical significance was determined using chi-square test. Table 3 showed more details.

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Table 3. Distribution of long lasting insecticidal nets utilization among women of reproductive age in Nigeria.

https://doi.org/10.1371/journal.pone.0254475.t003

Notably, only the variables which were statistically significant at the bivariate level (p<0.05) that were included. Results in Fig 1 showed that women who have access to media use, married and educated were more likely to uptake IPTp in North Central and South South, when compared with women without media use, unmarried and with no formal education respectively. Non-poor women from South East were more likely to uptake IPTp.

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Fig 1. Estimates of the odds of IPTp by respondents’ characteristics.

https://doi.org/10.1371/journal.pone.0254475.g001

In the bivariate analysis using chi-square test, only the variables which were statistically significant (p<0.05) were included. Fig 2 showed that rural dwellers were more likely to use LLINs, when compared with urban dwellers in North Central and South South respectively. Married women were less likely to use LLINs, when compared with unmarried women in North West. In addition, educated women were less likely to use LLINs, when compared with women with no formal education in South Eastern and South Southern States of Nigeria. In the North East, women aged 25–34 and 35+ were less likely to utilize long lasting insecticidal nets.

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Fig 2. Estimates of the odds of long lasting insecticidal nets utilization respondents’ characteristics.

https://doi.org/10.1371/journal.pone.0254475.g002

Discussion

This study has become one of the foremost to explore geopolitical zones differentials in IPTp and LLINs utilization in Nigeria. Our findings showed that there are disparities in IPTp uptake by geopolitical zones. This is consistent with the report of a previous study [29]. There were differences in IPTp uptake by geopolitical zones with North Central having the least coverage in Nigeria. Similarly, differences in LLINs utilization was identified. While South West had the least utilization, North East had the highest utilization respectively. Though massive campaigns for the distribution of LLINs have been going on for over a decade, only few studies have attempted to assess the rate of LLIN use. However, the studies did not report the rate of LLINs utilization before or after the massive campaigns, in both Nigeria and other sub-Saharan African countries [30–32]. Several factors dependent on geography, such as ethnicity, cultural norms and women’s enlightenment could have influenced IPTp and LLIN utilization in Nigeria.

The findings from this study revealed the factors associated with LLINs utilization and these varied by geopolitical zones. Rural dwellers, women who ever given birth to at least four children and those who use media were more likely to utilize LLINs, when compared with urban residents, those who had ever given birth to less than four children and who do not use the media. Conversely, the married women, educated, non-poor and those of advance age were less likely utilize LLINs when compared with the unmarried, uneducated, poor, and those below 25 years. This is in line with the findings of a previous study [23], where the rural dwellers had an increased LLINs utilization when compared with their counterparts from urban residence [23]. Another study that assessed the impact mass media campaign had on bed net utilization in Ethiopia showed that mass media has great influence in communicating to the people the need for LLINs and encouraging them to use it [33]. Contrary to our results, a previous study reported the use of LLINs in Eastern Nigeria was higher among small size families (family size less than four), compared to larger families [7]. Though the effectiveness of LLINs in protecting against malaria is evident, it is still difficult to achieve a corresponding ownership and utilization among women, particularly, the vulnerable or most at-risk population. This can be due to several factors and we recommend that future researchers could examine the cultural norms, perception, acceptability, myths and misconceptions using qualitative research approach.

Furthermore, the findings of this study showed that women who use media, married, educated and non-poor were more likely to uptake IPTp, when compared with their counterpart without media use, unmarried, with no formal education and poor respectively. As expected, married women are more eligible for the uptake of IPTp and the finding of higher uptake among the married folks is not a surprise. Similarly, the findings showed that educated women were more likely to uptake IPTp, when compared with those with no formal education. This agrees with the notion that educated women would have more knowledge about the benefits of malaria prevention during pregnancy. Women who were exposed to media use were more likely to have IPTp uptake, when compared to their counterpart who were not exposed to media use. Education and exposure to media use would enhance accessibility to behaviour change communication and consequently lead to increased health care utilization. The non-poor women were more likely to have IPTp uptake. It is assumed that the non-poor women are able to afford out-of-pocket expenditures for health care services, especially in resource-constrained settings [34–38]. Also, improved socioeconomic status among women is a predetermining factor for IPTp utilization.

Conclusion

This study shows that the utilization of IPTp and LLIN was relatively high despite that full coverage were yet to be achieved. Specifically, coverage was significantly different across geopolitical zones. Promoting the utilization of IPTp and LLINs by the most-at-risk across the six geopolitical zones through intensified health education and mass media campaigns will enhance full scale IPTp and LLIN utilization in Nigeria. There is need to enhance the strategies to increase IPTp and LLINs utilization as there are shortfalls in the national targets The findings of this study should be used by stakeholders who are involved in the massive distribution of LLINs and promotion of IPTp with emphasis on behavioural change communication especially among the pregnant women.

Acknowledgments

The appreciation of the authors goes to the MICS project coordinators for the approval and access to the original data.