Maintenance of high temporal Plasmodium falciparum genetic diversity and complexity of infection in asymptomatic and symptomatic infections in Kilifi, Kenya from 2007 to 2018
<strong>Background<br></strong> 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...
| Main Authors: | , , , , , , , , , |
|---|---|
| Format: | Journal article |
| Language: | English |
| Published: |
BioMed Central
2022
|
| _version_ | 1797108277518008320 |
|---|---|
| author | Kimenyi, KM Wamae, K Ngoi, JM de Laurent, ZR Ndwiga, L Osoti, V Obiero, G Abdi, AI Bejon, P Ochola-Oyier, LI |
| author_facet | Kimenyi, KM Wamae, K Ngoi, JM de Laurent, ZR Ndwiga, L Osoti, V Obiero, G Abdi, AI Bejon, P Ochola-Oyier, LI |
| author_sort | Kimenyi, KM |
| collection | OXFORD |
| description | <strong>Background<br></strong>
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.
<br><strong>
Methods<br></strong>
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.
<br><strong>
Results<br></strong>
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.
<br><strong>
Conclusions<br></strong>
Plasmodium falciparum infections in Kilifi are still highly diverse and polyclonal, despite the reduction in malaria transmission in the community. |
| first_indexed | 2024-03-07T07:26:57Z |
| format | Journal article |
| id | oxford-uuid:239ae4a9-0ead-428f-9a5f-627f84d08555 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:26:57Z |
| publishDate | 2022 |
| publisher | BioMed Central |
| record_format | dspace |
| spelling | oxford-uuid:239ae4a9-0ead-428f-9a5f-627f84d085552022-11-25T16:19:31ZMaintenance of high temporal Plasmodium falciparum genetic diversity and complexity of infection in asymptomatic and symptomatic infections in Kilifi, Kenya from 2007 to 2018Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:239ae4a9-0ead-428f-9a5f-627f84d08555EnglishSymplectic ElementsBioMed Central2022Kimenyi, KMWamae, KNgoi, JMde Laurent, ZRNdwiga, LOsoti, VObiero, GAbdi, AIBejon, POchola-Oyier, LI<strong>Background<br></strong> 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. <br><strong> Methods<br></strong> 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. <br><strong> Results<br></strong> 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. <br><strong> Conclusions<br></strong> Plasmodium falciparum infections in Kilifi are still highly diverse and polyclonal, despite the reduction in malaria transmission in the community. |
| spellingShingle | Kimenyi, KM Wamae, K Ngoi, JM de Laurent, ZR Ndwiga, L Osoti, V Obiero, G Abdi, AI Bejon, P Ochola-Oyier, LI Maintenance of high temporal Plasmodium falciparum genetic diversity and complexity of infection in asymptomatic and symptomatic infections in Kilifi, Kenya from 2007 to 2018 |
| title | Maintenance of high temporal Plasmodium falciparum genetic diversity and complexity of infection in asymptomatic and symptomatic infections in Kilifi, Kenya from 2007 to 2018 |
| title_full | Maintenance of high temporal Plasmodium falciparum genetic diversity and complexity of infection in asymptomatic and symptomatic infections in Kilifi, Kenya from 2007 to 2018 |
| title_fullStr | Maintenance of high temporal Plasmodium falciparum genetic diversity and complexity of infection in asymptomatic and symptomatic infections in Kilifi, Kenya from 2007 to 2018 |
| title_full_unstemmed | Maintenance of high temporal Plasmodium falciparum genetic diversity and complexity of infection in asymptomatic and symptomatic infections in Kilifi, Kenya from 2007 to 2018 |
| title_short | Maintenance of high temporal Plasmodium falciparum genetic diversity and complexity of infection in asymptomatic and symptomatic infections in Kilifi, Kenya from 2007 to 2018 |
| title_sort | maintenance of high temporal plasmodium falciparum genetic diversity and complexity of infection in asymptomatic and symptomatic infections in kilifi kenya from 2007 to 2018 |
| work_keys_str_mv | AT kimenyikm maintenanceofhightemporalplasmodiumfalciparumgeneticdiversityandcomplexityofinfectioninasymptomaticandsymptomaticinfectionsinkilifikenyafrom2007to2018 AT wamaek maintenanceofhightemporalplasmodiumfalciparumgeneticdiversityandcomplexityofinfectioninasymptomaticandsymptomaticinfectionsinkilifikenyafrom2007to2018 AT ngoijm maintenanceofhightemporalplasmodiumfalciparumgeneticdiversityandcomplexityofinfectioninasymptomaticandsymptomaticinfectionsinkilifikenyafrom2007to2018 AT delaurentzr maintenanceofhightemporalplasmodiumfalciparumgeneticdiversityandcomplexityofinfectioninasymptomaticandsymptomaticinfectionsinkilifikenyafrom2007to2018 AT ndwigal maintenanceofhightemporalplasmodiumfalciparumgeneticdiversityandcomplexityofinfectioninasymptomaticandsymptomaticinfectionsinkilifikenyafrom2007to2018 AT osotiv maintenanceofhightemporalplasmodiumfalciparumgeneticdiversityandcomplexityofinfectioninasymptomaticandsymptomaticinfectionsinkilifikenyafrom2007to2018 AT obierog maintenanceofhightemporalplasmodiumfalciparumgeneticdiversityandcomplexityofinfectioninasymptomaticandsymptomaticinfectionsinkilifikenyafrom2007to2018 AT abdiai maintenanceofhightemporalplasmodiumfalciparumgeneticdiversityandcomplexityofinfectioninasymptomaticandsymptomaticinfectionsinkilifikenyafrom2007to2018 AT bejonp maintenanceofhightemporalplasmodiumfalciparumgeneticdiversityandcomplexityofinfectioninasymptomaticandsymptomaticinfectionsinkilifikenyafrom2007to2018 AT ocholaoyierli maintenanceofhightemporalplasmodiumfalciparumgeneticdiversityandcomplexityofinfectioninasymptomaticandsymptomaticinfectionsinkilifikenyafrom2007to2018 |