High Plasmodium falciparum longitudinal prevalence is associated with high multiclonality and reduced clinical malaria risk in a seasonal transmission area of Mali

• Published in: PloS one 2017-02, Vol.12 (2), p.e0170948-e0170948
• Main Authors: Adomako-Ankomah, Yaw, Chenoweth, Matthew S, Durfee, Katelyn, Doumbia, Saibou, Konate, Drissa, Doumbouya, Mory, Keita, Abdoul S, Nikolaeva, Daria, Tullo, Gregory S, Anderson, Jennifer M, Fairhurst, Rick M, Daniels, Rachel, Volkman, Sarah K, Diakite, Mahamadou, Miura, Kazutoyo, Long, Carole A
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age; Analysis; Biology and Life Sciences; Blood; Care and treatment; Child; Child, Preschool; Computer and information sciences; Deoxyribonucleic acid; Disease transmission; DNA; Dry season; Epidemiology; Female; Gene sequencing; Health risks; Humans; Immunology; Infant; Infections; Infectious diseases; Influence; Laboratories; Longitudinal Studies; Malaria; Malaria, Falciparum - epidemiology; Malaria, Falciparum - parasitology; Male; Mali - epidemiology; Mathematical analysis; Medicine; Medicine and Health Sciences; Middle Aged; Parasites; People and Places; Pharmacy; Plasmodium falciparum; Plasmodium falciparum - pathogenicity; Plasmodium vivax; Polymerase Chain Reaction; Population studies; Prevalence; Prevalence studies (Epidemiology); Public health; Rainy season; Research and analysis methods; Risk; Risk factors; Risk reduction; Seasons; Single-nucleotide polymorphism; Studies; Vector-borne diseases; Young Adult
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0170948

The effects of persistent Plasmodium falciparum (Pf) infection and multiclonality on subsequent risk of clinical malaria have been reported, but the relationship between these 2 parameters and their relative impacts on the clinical outcome of infection are not understood. A longitudinal cohort study was conducted in a seasonal and high-transmission area of Mali, in which 500 subjects aged 1-65 years were followed for 1 year. Blood samples were collected every 2 weeks, and incident malaria cases were diagnosed and treated. Pf infection in each individual at each time point was assessed by species-specific nested-PCR, and Pf longitudinal prevalence per person (PfLP, proportion of Pf-positive samples over 1 year) was calculated. Multiclonality of Pf infection was measured using a 24-SNP DNA barcoding assay at 4 time-points (two in wet season, and two in dry season) over one year. PfLP was positively correlated with multiclonality at each time point (all r≥0.36; all P≤0.011). When host factors (e.g., age, gender), PfLP, and multiclonality (at the beginning of the transmission season) were analyzed together, only increasing age and high PfLP were associated with reduced clinical malaria occurrence or reduced number of malaria episodes (for both outcomes, P