Current strategies of Seasonal Malaria Chemoprevention, its challenges, and alternatives
Silva Soleiro Nunes Marcelino, Inês da
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Abstract Seasonal malaria chemoprevention (SMC) is a malaria control measure implemented in children aged between three and 59 months old, in countries of the Sahel region in Africa, which are characterised by highly seasonal transmission. A combination of sulfadoxine-pyrimethamine and amodiaquine (SP+AQ) is used monthly during four consecutive rounds. Clinical trials have shown suitable evidence on the efficacy of SMC. This review aims to provide an overview of the effectiveness and pitfalls of SMC, focusing on SP+AQ, and explore potential SMC drug combination alternatives. For this purpose, three databases were used. Articles were identified and selected through a screening process with inclusion and exclusion criteria, based on the PRISMA statement. Data were extracted from each full text article included in the review. Parameters included were malaria prevalence, incidence, mortality, anaemia status, and gametocytaemia, depending on the measurements and outcomes of each study. Details on adverse reactions and resistance markers were also collected. A final total of 31 articles were included in the review. SP+AQ conferred a protective efficacy against clinical malaria ranging from around 60% to 85% over 28 days, in five- to 59-month-olds. The drug combination was found to be well tolerated with low number of serious adverse effects, and vomiting was the most commonly reported reaction identified in this review. The presence of P. falciparum resistant genes (Pfmdr1, Pfdhps and Pfdhfr) was generally low throughout all studies. Dihydroartemisinin-piperaquine (DHA+PQ), which is already approved for treatment of uncomplicated malaria, was the second most studied drug combination. It conferred a protective efficacy against clinical malaria cases of 74% within 4 weeks post drug administration. It was also well tolerated, with no serious adverse effects reported, and the frequency of resistance genes was lower compared to that of SP+AQ. Overall, SP+AQ is a drug combination that is effective at reducing malaria prevalence and incidence in children under five years of age, in areas of seasonal malaria transmission. It is however important to maintain efficient surveillance systems to continuously monitor the presence of resistance and drug safety. Extending SMC implementation to include older children and more numbers of rounds proved to be beneficial based on various trials. In areas where SP+AQ might not be suitable due to development of resistance, DHA+PQ appears to be an appropriate alternative. Additional studies would be valuable to further assess DHA+PQ’s efficacy and coverage when implemented at a larger scale, in order to evaluate its potential usage for SMC.