Effect of Seasonal Malaria Chemoprevention (SMC) with SulfadoxinePyrimethamine (SP) and Amodiaquine (AQ) on the Acquisition of antiAMA1 and anti-MSP1_42 Antibodies among Children under 10 Years Living in the Southern part of Senegal (Velingara)

Abstract

Background: In developing countries, malaria is still a leading cause of morbidity and mortality and children are the most affected individuals. In order to strengthen malaria control, new intervention such as Seasonal Malaria Chemoprevention (SMC) has been developed. This strategy is very effective in preventing malaria clinical episodes but its effect on children’s immunity is not well documented. This study aimed to evaluate the effects of SMC on the acquisition of anti-AMA1 and anti-MSP1_42 antibodies among children fewer than 10 years living in the southern part of Senegal (Velingara). Patients and methods: The study was nested in a cluster randomized trial assessing the impact of SMC with a single dose of Sulfadoxine-Pyrimethamine (SP) and 3 doses of Amodiaquine (AQ). Two cross-sectional surveys were carried out (October 2010) and (September 2011) to assess the effect of SMC on children’s immunity. Thick and thin blood smears were performed to assess malaria parasiteamia prevalence. Blood was collected on filter paper for serological measurement by ELISA to measure IgG anti-MSP1_42 and anti-AMA1. Logistic regression analysis was performed to assess factors associated with the production of antibodies. Results: A total number of 1611 children under 10 years old were included in two surveys (866 children in 2010 and 745 children in 2011). Malaria prevalence was 10.39% at baseline (2010) and 5.03% one year after intervention (2011). The seroprevalence of anti-MSP1_42 anti-AMA1 antibodies was higher in 2010 compared to 2011 providing a significant reduction of IgG production at 11.4 AU (95%CI ⦋8.3-14.4⦌) for MSP1_42 and 7.2 AU (95%CI ⦋4.5-9.9⦌) for AMA1. Seroprevalence increased with age and Plasmodium falciparum carriage while it decreased according to the area and study period. Conclusion: SMC is an effective strategy for malaria prevention in children under 10 years. The strategy can as well induce a decrease of IgG anti-AMA1 and anti-MSP1_42 which are protective against malaria. Consequently, this strategy needs to be renewed each year in areas where malaria is highly seasonal to avoid a resurgence of malaria, while promoting the use of other antimalarial interventions.