Gametocyte production in incident P. falciparum infections: a longitudinal study in a low transmission setting under intensive vector control

Malaria transmission depends on the presence of Plasmodium gametocytes that are the only parasite life stage that can infect mosquitoes. Gametocyte production varies between infections and over the course of infections. Infection duration is influenced by host and parasite characteristics, and is highly important for gametocyte production but poorly quantified. Between 2017-2019 an all-age cohort from Tororo, eastern Uganda was followed by continuous passive and routine assessments. Among 104 longitudinally monitored incident infections coming from 98 individuals, we observed that nearly all infections lasting 3 or more months initiated gametocyte production prior to clearance. However, the majority of infections were of shorter duration (<28 days) and were cleared before gametocytes were detectable. Infections in individuals with sickle-cell trait were more likely to produce gametocytes and produced gametocytes at higher densities. Our findings suggest that a large proportion of infections may be too short in duration and of too low density to contribute to onward transmission.