This study aims to improve the understanding of the seasonal changes in the asymptomatic carriage of P. falciparum, and its links with local malaria transmission dynamics. The study consists in a cohort of household members in 8 villages: 4 in Eastern Senegal (Kédougou region), 2 near Bamako, Mali (Kati Region) and 2 in Northern Mali (Diré region). Target number of participants is 150 per village, corresponding to roughly 20 households. This study is represented by 4 study codes, with 1316 and 1317 representing samples collected in Mali and 1318 and 1319 representing samples collected in Senegal.

Study participants are followed through 4 prevalence surveys over 12 months: baseline (dry season 2022, April-May), at the onset of rainy season (before CPS starts, June-July 21), during the transmission season (Nov-Dec 2021) and dry season 2022. Mobility follow-up is conducted weekly. Prevalence survey samples are analysed by qPCR to detect Plasmodium carriage.

During the study (12 months) clinical malaria episodes are followed up for all village populations. Malaria diagnostic (RDT) and treatment is available in the village from a community health worker or health post. Dried blood spots (DBS) sample collection upon passive detection of clinical malaria depends on the site: in Senegal, DBS are collected for all RDT-positive consenting individuals  (whether included in the cohort or not); in sites near Bamako, DBS are collected for all RDT-positive cohort members; in Northern Mali, no sample collection was performed for passively detected malaria cases.