Force of Infection (FOI) and Multiplicity of Infection (MOI) in Plasmodium falciparum Infected Children Aged 1.5–12 Years Living in the Malaria Endemic Area of Banfora, Burkina Faso

Abstract

The aim of this study was to explore molecular measures of P. falciparum malaria burden (FOI and MOI) in the context of seasonal malaria chemoprevention. We analyzed malaria cases collected as part of a longitudinal cohort study. The cohort included P. falciparum-negative children aged 1.5 to 12, as confirmed by PCR 21 days after a radical cure using DHA-PQ or AS. Children were followed up for six months using active and passive case detection methods. At each visit, dried blood spots and blood smears were collected by finger prick, along with clinical data. Parasite DNA was extracted and analyzed by nested PCR for detection and genotyping of P. falciparum parasites. A total of 458 P. falciparum isolates collected during follow-up from October 2020 to March 2021 were genotyped. During the follow-up, children contracted 1.05 (95% IC [0.81–1.30]) new P. falciparum infections/child/time of exposure, and the MOI value was 3.00 (SD 1.60). Age is a protective factor (IRR: 0.74; 95% CI: 0.61, 0.90) against the occurrence of an episode of malaria, unlike an increase in MOI (IRR: 1.63; 95% CI: 1.04, 1.99), which is a favorable factor (p < 0.05). This study confirms the reduction in malaria transmission in our study area, probably due to the massive deployment of control tools.