Dynamics of Plasmodium species and genotype diversity in adults with asymptomatic infection in Gabon

Abstract

ObjectivesWe investigated the diversity and dynamics of Plasmodium infection in serially collected samples from asymptomatic participants of a clinical trial assessing efficacy and safety of ivermectin in Gabon. We checked whether the baseline sample reflected P. falciparum genotype and Plasmodium species diversity seen over seven days of follow-up. MethodsBlood samples were collected at inclusion, every 8 hours until hour 72, daily until day seven, and on day 14. Plasmodium species was determined by qPCR and pfmsp1 length polymorphism was assessed for P. falciparum genotyping. ResultsIn 17/48 (35%) individuals, all pfmsp1 genotypes identified during the assessed period were detected at baseline; in 31/48 (65%), new genotypes were found during follow-up. Additional sampling at hour 24 allowed the identification of all genotypes seen over seven days in 50% of the individuals. Ivermectin did not impact the genotype dynamics. Mixed Plasmodium spp. infections were detected in 28/49 (57%) individuals at baseline, and detection of non-falciparum infections during follow-up varied. ConclusionsOur results reveal complex intra-host dynamics of P. falciparum genotypes and Plasmodium species and underscore the importance of serial sampling in clinical trials for antimalarial drugs with asymptomatically P. falciparum-infected individuals. This might allow a more accurate identification of genotypes in multiple infections, impacting the assessment of drug efficacy.