1. Maintenance of high temporal Plasmodium falciparum genetic diversity and complexity of infection in asymptomatic and symptomatic infections in Kilifi, Kenya from 2007 to 2018.
- Author
-
Kimenyi KM, Wamae K, Ngoi JM, de Laurent ZR, Ndwiga L, Osoti V, Obiero G, Abdi AI, Bejon P, and Ochola-Oyier LI
- Subjects
- Antigens, Protozoan genetics, Asymptomatic Infections epidemiology, Child, Cross-Sectional Studies, Fever, Genetic Variation, Genotype, Humans, Kenya epidemiology, Protozoan Proteins genetics, Malaria, Falciparum epidemiology, Malaria, Falciparum parasitology, Plasmodium falciparum genetics
- Abstract
Background: High levels of genetic diversity are common characteristics of Plasmodium falciparum parasite populations in high malaria transmission regions. There has been a decline in malaria transmission intensity over 12 years of surveillance in the community in Kilifi, Kenya. This study sought to investigate whether there was a corresponding reduction in P. falciparum genetic diversity, using msp2 as a genetic marker., Methods: Blood samples were obtained from children (< 15 years) enrolled into a cohort with active weekly surveillance between 2007 and 2018 in Kilifi, Kenya. Asymptomatic infections were defined during the annual cross-sectional blood survey and the first-febrile malaria episode was detected during the weekly follow-up. Parasite DNA was extracted and successfully genotyped using allele-specific nested polymerase chain reactions for msp2 and capillary electrophoresis fragment analysis., Results: Based on cross-sectional surveys conducted in 2007-2018, there was a significant reduction in malaria prevalence (16.2-5.5%: P-value < 0.001), however msp2 genetic diversity remained high. A high heterozygosity index (He) (> 0.95) was observed in both asymptomatic infections and febrile malaria over time. About 281 (68.5%) asymptomatic infections were polyclonal (> 2 variants per infection) compared to 46 (56%) polyclonal first-febrile infections. There was significant difference in complexity of infection (COI) between asymptomatic 2.3 [95% confidence interval (CI) 2.2-2.5] and febrile infections 2.0 (95% CI 1.7-2.3) (P = 0.016). Majority of asymptomatic infections (44.2%) carried mixed alleles (i.e., both FC27 and IC/3D7), while FC27 alleles were more frequent (53.3%) among the first-febrile infections., Conclusions: Plasmodium falciparum infections in Kilifi are still highly diverse and polyclonal, despite the reduction in malaria transmission in the community., (© 2022. The Author(s).)
- Published
- 2022
- Full Text
- View/download PDF