PROJECT SUMMARY
According to the World Health Organization (WHO), in 2018, there were an estimated 405 000 deaths from
malaria. Children aged under 5 years are the most vulnerable group affected by malaria and accounted for 67%
(272 000) of all malaria deaths worldwide. The WHO African Region was home to the highest number of
malaria deaths in with 94% of all malaria deaths in 2018. In regions with highly seasonal malaria transmission,
several studies have shown a sharp decline in malaria infections through the use of intermittent preventive
treatment pregnant women and young children between the ages of three and fifty-nine months. Seasonal
malaria chemoprevention (SMC) in these young children consists of treatment courses of sulfadoxine–
pyrimethamine plus amodiaquine given at monthly intervals during the malaria season to maintain therapeutic
anti-malarial drug concentrations in the blood throughout the period of greatest malaria risk. Despite the
substantial benefits provided by SMC, one concern is that SMC will impair the acquisition of protective
immune responses, thereby increasing the risk of disease in later years. Studies have shown changes in the ages
of peak susceptibility to malaria, with older children more vulnerable to disease following the implementation
of control strategies. In 2016, SMC was implemented nationwide in Mali. This project will measure the age-
specific incidence of malaria in children in Bandiagara, a rural town in central Mali that has been a malaria field
research site for two decades. This will include three age groups: 0-4 years (representing the targeted group for
SMC), 5-10 years (a “mixed” group of children who received SMC and older ones who did not) and 11-18
years (no history of SMC). We will compare the incidence of asymptomatic and symptomatic malaria to that
measured in similar strata before the implementation of seasonal malaria chemoprevention in the community.
Using custom protein microarrays, we will compare the antibody responses to malaria antigens by age group
before and with SMC implementation. We will identify and map the spatial distribution of parasite reservoirs
(including both symptomatic and asymptomatic parasite carriage) using ultra-sensitive molecular testing and
define asymptomatic parasite carrier hotspots, particularly in the dry season (January to May). The dry season is
of particular interest because during this period, parasite carriage (symptomatic or asymptomatic carriage) and
transmission (gametocyte carriage) are very low, and the human reservoir of parasites is significantly reduced.
The dry season is thus a critical temporal window of opportunity to eliminate malaria. The results of this study
will define the consequences of SMC in pediatric populations in Mali and identify parasite reservoirs, helping to
shape new approaches for future malaria control strategies, including treating populations with high
asymptomatic carriage and targeting mosquito populations in defined hotspots.
