Study of the coverage and the impact of the chemoprevention of seasonal malaria in Niger from 2013 to 2022: systematic review

Introduction

Malaria remains one of the most significant public health challenges globally, especially in sub-Saharan Africa, where the burden of the disease is disproportionately high.¹ It is transmitted to humans by the bite of an infected female Anopheles mosquito and occurs mainly in tropical regions.² Although preventable and treatable, malaria remains a major challenge in Niger, where it is endemic and exposes the entire population to a high risk.³ The disease represents a considerable financial burden for households and constitutes an obstacle to the country’s development. According to the latest Global Malaria Report, there were 263 million cases of malaria in 2023, compared to 252 million in 2022. The estimated number of deaths due to malaria was 597,000 in 2023, down slightly from 600,000 in 2022. The WHO African Region continues to bear a large and disproportionate share of the global malaria burden. In 2023, approximately 94% of malaria cases and 95% of malaria-related deaths occurred in this region. Children under five accounted for about 76% of these deaths. More than half of them took place in four countries: Nigeria (30.9%), the Democratic Republic of the Congo (11.3%), Niger (5.9%), and the United Republic of Tanzania (4.3%).⁴ In fact, in 2021, 58% of the 4,182 malaria-related deaths in Niger occurred among children in this age group. Despite efforts to combat the disease, the situation remains concerning. In 2023, the population at risk in Niger was 26,207,976, with 4,461 recorded deaths, 35,381 estimated deaths, and 3,937,742 suspected and confirmed cases.⁴ In response to this crisis, the WHO launched a strategy in 2016 based on three pillars: (a) universal access to prevention, diagnosis, and treatment; (b) elimination of transmission; and (c) epidemiological surveillance⁵. This approach emphasizes innovation, research, and multidisciplinary collaboration. In Niger, seasonal malaria chemoprevention (SMC) was introduced in 2013, in line with WHO recommendations.⁶ This intervention involves administering sulfadoxine-pyrimethamine and amodiaquine over three days, one month apart, to children aged 3 to 59 months during the transmission season.⁷ In regard to these recommendations, studies were conducted in several, including Burkina Faso, Mali, Niger, and The Gambia, have shown a significant reduction in malaria-related deaths, with a protective efficacy of 88.2% over 28 days.⁸ However, effective implementation of SMC requires rigorous monitoring to assess its impact and community acceptance. Moreover, the evolving epidemiology of malaria has led to the adoption of targeted strategies tailored to the specific characteristics of different areas and populations. In Niger, the 2022 campaign covered 67 health districts and introduced a fifth treatment cycle in certain districts based on their epidemiological profile.

In this context, we conducted a systematic literature review to assess the coverage and impact of SMC in Niger between 2013 and 2022. The objective of this review is to evaluate the effectiveness of SMC in preventing malaria episodes, as measured by adherence to the treatment regimen. Secondary outcomes include the occurrence of adverse events and the measurement of incidence and prevalence. Identifying implementation gaps is essential to inform future strategies and strengthen malaria control efforts in Niger. Understanding the successes and challenges of SMC in this context is critical for guiding policy decisions.

Methods

Results

Through searches across various databases, 198 publications were identified, of which 6 met the eligibility criteria for inclusion in the final review ( Figure 1). These articles were published between 2013 and 2022. Among them, one was a case-control study, one was a survey synthesis report, and the remaining four were evaluation studies ( Table 3).

Figure 1. Flow diagram of study selection process.

Impact of seasonal malaria chemoprevention

A single case study was conducted to estimate the public health impact of seasonal malaria chemoprevention (SMC). The study aimed to compare the incidence of malaria in six Integrated Health Centres (IHCs) where SMC was implemented with that in six other IHCs not benefiting from the intervention.⁶ It focused on several indicators, including malaria incidence, number of cases averted, reduction in parasitaemia, number of hospitalisations, and malaria-related deaths following the introduction of SMC. The results showed that SMC significantly reduces parasite carriage and load. It decreased the incidence of uncomplicated malaria by 73% and showed a strong correlation with the reduction in malaria episodes (R = 0.59). Additionally, SMC reduced the incidence of severe malaria by 26.5%, convulsions by 19.9%, and hospitalisations by 23%. It also had a notable impact on reducing coma (13.2%) and mortality (48.3%) ( Figure 2). However, no significant reduction in anaemia was observed.

Figure 2. Summary of the impact of the SMC on the different indicators studied.

Adverse reactions (ARs)

In the 2016 study on the implementation of SMC, we found that during the four cycles of SMC, 224 cases of non-serious adverse events (AEs) were reported by the national pharmacovigilance system. Prior to the start of the SMC cycles, all health workers and communities were sensitized to the possibility of AEs. The incidence rate was 0.82 per 10,000. The most commonly reported AEs were digestive disorders such as nausea, vomiting, abdominal pain, and diarrhea. Other symptoms were fever, anorexia, and pruritus. The regional distribution of AEs is presented in ( Figure 3).¹²

Figure 3. Distribution of adverse events (AEs) by region.

In a second study some minor side effects have been observed dominated by vomiting (54%) Some minor side effects have been observed dominated by vomiting (54%).¹⁴

Discussions

This study reviewed and synthesized six studies in the context of the chemoprevention of seasonal malaria in children aged 3 to 59 months. SMC significantly reduced malaria incidence rates and moderately reduced severe malaria. It also led to reductions in moderate anemia and all-cause hospitalization rates in high and moderate transmission zones, along with a decrease in mortality rates. To better contextualize these results, it is important to compare them with those from other countries that have implemented SMC. In Niger, we observed a 48.3% reduction in mortality rates. These results are comparable to a study in Burkina Faso, which found a 42.3% reduction in hospital deaths during the high transmission season, while in The Gambia, this reduction reached up to 56.6%.⁸

As for simple and severe malaria, the rates observed were 73% and 48.3%, respectively. These results are lower than those found in Nigeria, where malaria incidence was reduced by 35% to 45%.¹⁶ These results may be explained by the effective implementation of complementary control strategies in Niger, such as the use of insecticide-treated mosquito nets and indoor residual spraying. Additionally in Mali, SMC was associated with a 55% reduction in severe malaria and a 40% reduction in hospitalizations. These results are higher than those found in Niger, which reported reductions of 26.5% and 23%, respectively. This difference could be attributed to higher SMC coverage and better population adherence within the country.¹⁷ Moreover, when comparing our results with those from Chad, which implemented SMC in 2014, a 35% reduction in malaria incidence was observed, with a coverage rate of 50%. These results are similar to those found in remote and insecure areas of Niger,¹⁸ where low coverage may be due to logistical challenges and limited community buy-in. Furthermore, our results on incidence are also higher than those found in Uganda, which reported a 43% reduction in confirmed cases.¹⁹ This difference could be explained by the broader SMC coverage in Niger (74.4% in 2015) and its earlier implementation in 2013, which may have led to greater community adherence to the strategy.¹¹

SMC has shown substantial reductions in uncomplicated malaria incidence, with rate ratios indicating a 73% decrease in malaria cases among children under five.²⁰ In Nigeria, SMC significantly reduced the malaria burden among under-five children, with a 2% decrease in case numbers and a 3.5% reduction in deaths between 2020 and 2021. In 2023, 53 million children were covered, primarily through door-to-door distribution and community-based interventions.²¹ When comparing this study with a 2021 review that included twelve randomized studies, the results were stratified by age (<5 years and ≥5 years), number of cycles (three or four versus five or six), and, where possible, by drug type. The drug regimens examined included sulfadoxine-pyrimethamine combined with amodiaquine, amodiaquine-sulfadoxine, and sulfadoxine-pyrimethamine combined with artesunate. All included studies were conducted in Sahelian countries, where high-grade resistance to sulfadoxine-pyrimethamine was lower, and in areas where parasite prevalence ranged from 1% to 79%. The study demonstrated a significant reduction in the incidence of uncomplicated malaria during the transmission season. Additionally, there was a notable decrease in the prevalence of malaria parasitemia.²⁰ What is more research entitled ACCESS-SMC reveals some evidence that seasonal malaria chemoprevention with SPAQ is well tolerated. During the four SMC cycles, 224 cases of non-serious adverse events (AEs) were reported by the national pharmacovigilance system. In comparison, other countries reported 36 serious adverse events through the ACCESS-SMC partnership in 2015 and 2016, including one rash, two fevers, one extrapyramidal syndrome, one angioedema, and 31 gastrointestinal disorders.²²

Regarding the coverage of SMC, it should be noted that, at the national level, coverage in 2016 was 85.75%. The regions of Tahoua, Zinder, Dosso, Diffa, Maradi, Tillabéri, and Niamey had coverage rates of 85%, 99%, 75%, 73%, 73%, 84%, 79%, and 59%, respectively.¹² While the overall coverage is high, the results show regional variation. It is also important to note that, in the absence of reliable data on the target population, administrative coverage may not reflect the actual coverage of the SMC program. This justifies the need for cross-sectional surveys to measure program coverage at least once, at the end of the four SMC distributions. Improving health system performance and data availability is crucial for enhancing SMC coverage and ensuring equitable access to preventive measures.²³ Though there were no comparisons between children who received three or four rounds of SMC in Niger. The results are lower than those found in a study in Ghana, which had 90% coverage and showed similar risk reductions in the three- and four-round trials. Other studies have also compared delivery methods and dosing regimens, reporting innovations such as door-to-door distribution and direct observation of the first dose by the distributor.

Even though coverage is high in Niger, the incidence rate is lower than that found in the Ugandan study, which showed that SMC using sulfadoxine-pyrimethamine and amodiaquine (SPAQ) resulted in a 92% reduction in malaria incidence among children aged 3–59 months during peak transmission seasons (“A non-randomised controlled trial to assess the protective effect of SMC in the context of high parasite resistance in Uganda,” 2022).²⁴ In intervention areas, 90% of children did not experience malaria episodes, compared to only 15% in control areas, indicating the substantial impact of SMC on public health. This difference could be explained by the quality of the implementation of the intervention or by epidemiological conditions.

In terms of resistance, Niger is in the Sahel zone, where SP resistance is relatively low. One study found some evidence that seasonal malaria chemoprevention with SPAQ affects antibody responses to blood-stage and pre-erythrocytic stages of P. falciparum infections in Niger.¹³ Unlike Burkina Faso, where similar studies have been conducted, these studies have shown that SMC with SPAQ provides strong immune protection without negatively impacting the development of natural immunity.²⁵ In Nigeria, however, resistance to SP has been reported in some regions.¹⁶ Although resistance remains low in Niger, there is a need to implement a monitoring system to better adapt the strategy. This review provided an overview of the studies conducted in Niger regarding seasonal malaria chemoprevention, focusing specifically on coverage and its impact.

Some key factors for the successful implementation of SMC include high coverage, community adherence, and the integration of SMC with other complementary strategies. These factors are often associated with a positive impact on reducing malaria-related morbidity and mortality. It is important to note that community engagement and the participation of local leaders are crucial to ensuring acceptance of SMC. Despite its performance, challenges persist in the implementation of SMC. These include variations in coverage between rural and urban areas, logistical and financial constraints, and drug resistance in some regions.

To improve the implementation of SMC in Niger, particular attention must be paid to increasing coverage in rural and remote areas. Community participation should also be strengthened through awareness-raising and the integration of other malaria control strategies, such as insecticide-treated mosquito nets and epidemiological surveillance. These findings also highlight that very few studies have been conducted to assess the coverage and impact of SMC since its implementation in Niger in 2013. While district-level results show satisfactory coverage of over 80%, they do not reflect national-level coverage. This underscores the need to conduct further research to generate comprehensive data for improving the strategy.

Conclusion

Seasonal malaria chemoprevention (SMC) has proven to be highly effective, with an acceptable coverage rate that is well accepted by the population in Niger. The results are comparable to those observed in other countries where the SMC program is implemented. This review highlights that several studies have addressed various aspects of malaria chemoprevention, including its effectiveness, public health impact, coverage, and adverse effects. These studies have produced satisfactory results, underscoring the importance of SMC as a key strategy in the fight against malaria. However, there are still very few studies specifically focusing on the coverage and impact of SMC in Niger, which highlights the need for further research to strengthen and improve the strategy.

Ethics and consent

Ethical approval and consent were not required.