Asymptomatic school-age children carry the majority of transmissible Plasmodium falciparum infections

Résumé fourni par la source

Persistent human-to-mosquito parasite transmission hinders malaria control in high burden settings. Understanding the human transmission reservoir can support the design of targeted interventions to reduce transmission. In a year-long cohort study in rural Malawi, we used molecular methods to detect all Plasmodium falciparum (Pf) infections and those containing gametocytes, the parasite stage required for transmission, longitudinally at routine surveillance and sick visits. Using population-level analyses, we determined the demographic, temporal, and spatial clustering of infections containing gametocytes and gametocyte density, which predicts transmission. Here we show that gametocytes are not randomly distributed among the population or among individuals with Pf infections; gametocytes are detected in only 23% of the population. Among all participants, school-age children have significantly higher incidence of gametocyte-containing infections and high-density gametocyte infections compared to other groups. The presence of school-age children is a key driver of gametocyte frequencies and densities within households, even after adjusting for Pf infection levels. Based on the total gametocyte abundance in the population, we estimate that clearing infections from asymptomatic school-age children in the rainy season would decrease gametocyte abundance by 67% in the population. School-age children are the primary driver of ongoing Pf transmission in Malawi and interventions targeting school-age children are needed to effectively reduce Pf infection risk at a population level. This study aimed to investigate how malaria spreads in rural Malawi and which groups drive infection spread. We followed all the people in clusters of homes for a year to see when and how often the stage of malaria parasites that can infect mosquitoes (called gametocytes) appeared. We also examined whether gametocytes tended to cluster within the same households and other correlates of detecting gametocytes. Age was the strongest factor linked to having gametocytes, more so than any other condition we tested. We found that school-age children carried most of the gametocytes and thus, they contribute the most to the spread of malaria. This means that efforts to reduce malaria should pay special attention to school-age children, as progress toward eliminating malaria will likely depend on treating and preventing infections in this group. Buchwald et al. conducted a year-long prospective, open-enrollment cohort study in southern Malawi and examined the demographic, temporal, and spatial clustering of transmission-relevant (gametocyte containing) Plasmodium falciparum infections. They found that school-age children are the primary driver of ongoing Plasmodium falciparum transmission.

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