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Osborne A, Phelan JE, Kaneko A, Kagaya W, Chan C, Ngara M, Kongere J, Kita K, Gitaka J, Campino S, Clark TG. Drug resistance profiling of asymptomatic and low-density Plasmodium falciparum malaria infections on Ngodhe island, Kenya, using custom dual-indexing next-generation sequencing. Sci Rep 2023; 13:11416. [PMID: 37452073 PMCID: PMC10349106 DOI: 10.1038/s41598-023-38481-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 07/09/2023] [Indexed: 07/18/2023] Open
Abstract
Malaria control initiatives require rapid and reliable methods for the detection and monitoring of molecular markers associated with antimalarial drug resistance in Plasmodium falciparum parasites. Ngodhe island, Kenya, presents a unique malaria profile, with lower P. falciparum incidence rates than the surrounding region, and a high proportion of sub-microscopic and low-density infections. Here, using custom dual-indexing and Illumina next generation sequencing, we generate resistance profiles on seventy asymptomatic and low-density P. falciparum infections from a mass drug administration program implemented on Ngodhe island between 2015 and 2016. Our assay encompasses established molecular markers on the Pfcrt, Pfmdr1, Pfdhps, Pfdhfr, and Pfk13 genes. Resistance markers for sulfadoxine-pyrimethamine were identified at high frequencies, including a quintuple mutant haplotype (Pfdhfr/Pfdhps: N51I, C59R, S108N/A437G, K540E) identified in 62.2% of isolates. The Pfdhps K540E biomarker, used to inform decision making for intermittent preventative treatment in pregnancy, was identified in 79.2% of isolates. Several variants on Pfmdr1, associated with reduced susceptibility to quinolones and lumefantrine, were also identified (Y184F 47.1%; D1246Y 16.0%; N86 98%). Overall, we have presented a low-cost and extendable approach that can provide timely genetic profiles to inform clinical and surveillance activities, especially in settings with abundant low-density infections, seeking malaria elimination.
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Affiliation(s)
- Ashley Osborne
- Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
| | - Jody E Phelan
- Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Akira Kaneko
- Department of Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Wataru Kagaya
- Department of Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
| | - Chim Chan
- Department of Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
| | - Mtakai Ngara
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - James Kongere
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
- Department of Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Centre for Research in Tropical Medicine and Community Development (CRTMCD), Hospital Road Next to Kenyatta National Hospital, Nairobi, Kenya
| | - Kiyoshi Kita
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
| | - Jesse Gitaka
- Directorate of Research and Innovation, Mount Kenya University, Thika, Kenya
- Centre for Malaria Elimination, Mount Kenya University, Thika, Kenya
| | - Susana Campino
- Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Taane G Clark
- Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK.
- Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK.
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Schneider KA, Tsoungui Obama HCJ, Kamanga G, Kayanula L, Adil Mahmoud Yousif N. The many definitions of multiplicity of infection. FRONTIERS IN EPIDEMIOLOGY 2022; 2:961593. [PMID: 38455332 PMCID: PMC10910904 DOI: 10.3389/fepid.2022.961593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Accepted: 09/06/2022] [Indexed: 03/09/2024]
Abstract
The presence of multiple genetically different pathogenic variants within the same individual host is common in infectious diseases. Although this is neglected in some diseases, it is well recognized in others like malaria, where it is typically referred to as multiplicity of infection (MOI) or complexity of infection (COI). In malaria, with the advent of molecular surveillance, data is increasingly being available with enough resolution to capture MOI and integrate it into molecular surveillance strategies. The distribution of MOI on the population level scales with transmission intensities, while MOI on the individual level is a confounding factor when monitoring haplotypes of particular interests, e.g., those associated with drug-resistance. Particularly, in high-transmission areas, MOI leads to a discrepancy between the likelihood of a haplotype being observed in an infection (prevalence) and its abundance in the pathogen population (frequency). Despite its importance, MOI is not universally defined. Competing definitions vary from verbal ones to those based on concise statistical frameworks. Heuristic approaches to MOI are popular, although they do not mine the full potential of available data and are typically biased, potentially leading to misinferences. We introduce a formal statistical framework and suggest a concise definition of MOI and its distribution on the host-population level. We show how it relates to alternative definitions such as the number of distinct haplotypes within an infection or the maximum number of alleles detectable across a set of genetic markers. It is shown how alternatives can be derived from the general framework. Different statistical methods to estimate the distribution of MOI and pathogenic variants at the population level are discussed. The estimates can be used as plug-ins to reconstruct the most probable MOI of an infection and set of infecting haplotypes in individual infections. Furthermore, the relation between prevalence of pathogenic variants and their frequency (relative abundance) in the pathogen population in the context of MOI is clarified, with particular regard to seasonality in transmission intensities. The framework introduced here helps to guide the correct interpretation of results emerging from different definitions of MOI. Especially, it excels comparisons between studies based on different analytical methods.
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