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Debrah I, Zhong D, Machani MG, Nattoh G, Ochwedo KO, Morang'a CM, Lee MC, Amoah LE, Githeko AK, Afrane YA, Yan G. Non-Coding RNAs Potentially Involved in Pyrethroid Resistance of Anopheles funestus Population in Western Kenya. Res Sq 2024:rs.3.rs-3979432. [PMID: 38464038 PMCID: PMC10925441 DOI: 10.21203/rs.3.rs-3979432/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Backgrounds The resurgence of Anopheles funestus , a dominant vector of human malaria in western Kenya was partly attributed to insecticide resistance. However, evidence on the molecular basis of pyrethroid resistance in western Kenya is limited. Noncoding RNAs (ncRNAs) form a vast class of RNAs that do not code for proteins and are ubiquitous in the insect genome. Here, we demonstrated that multiple ncRNAs could play a potential role in An. funestus resistance to pyrethroid in western Kenya. Materials and Methods Anopheles funestus mosquitoes were sampled by aspiration methods in Bungoma, Teso, Siaya, Port Victoria and Kombewa in western Kenya. The F1 progenies were exposed to deltamethrin (0.05%), permethrin (0.75%), DDT (4%) and pirimiphos-methyl (0.25%) following WHO test guidelines. A synergist assay using piperonyl butoxide (PBO) (4%) was conducted to determine cytochrome P450s' role in pyrethroid resistance. RNA-seq was conducted on a combined pool of specimens that were resistant and unexposed, and the results were compared with those of the FANG susceptible strain. This approach aimed to uncover the molecular mechanisms underlying pyrethroid resistance. Results Pyrethroid resistance was observed in all the sites with an average mortality rate of 57.6%. Port Victoria had the highest level of resistance to permethrin (MR=53%) and deltamethrin (MR=11%) pyrethroids. Teso had the lowest level of resistance to permethrin (MR=70%) and deltamethrin (MR=87%). Resistance to DDT was observed only in Kombewa (MR=89%) and Port Victoria (MR=85%). A full susceptibility to P-methyl (0.25%) was observed in all the sites. PBO synergist assay revealed high susceptibility (>98%) to the pyrethroids in all the sites except for Port Victoria (MR=96%, n=100). Whole transcriptomic analysis showed that most of the gene families associated with pyrethroid resistance comprised non-coding RNAs (67%), followed by imipenemase (10%),cytochrome P450s (6%), cuticular proteins (5%), olfactory proteins (4%), glutathione S-transferases (3%), UDP-glycosyltransferases (2%), ATP-binding cassettes (2%) and carboxylesterases(1%). Conclusions This study unveils the molecular basis of insecticide resistance in An. funestus in western Kenya, highlighting for the first time the potential role of non-coding RNAs in pyrethroid resistance. Targeting non-coding RNAs for intervention development could help in insecticide resistance management.
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Debrah I, Ochwedo KO, Otambo WO, Machani MG, Magomere EO, Onyango SA, Zhong D, Amoah LE, Githeko AK, Afrane YA, Yan G. Genetic Diversity and Population Structure of Anopheles funestus in Western Kenya Based on Mitochondrial DNA Marker COII. Insects 2023; 14:273. [PMID: 36975958 PMCID: PMC10052146 DOI: 10.3390/insects14030273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 02/26/2023] [Accepted: 03/07/2023] [Indexed: 06/18/2023]
Abstract
The mitochondrial marker, COII, was employed to assess the genetic structure and diversity of Anopheles funestus, a very important malaria vector in Africa that adapt and colonize different ecological niches in western Kenya. Mosquitoes were collected using mechanical aspirators in four areas (Bungoma, Port Victoria, Kombewa, and Migori) in western Kenya. Following morphological identification, PCR was used to confirm the species. The COII gene was amplified, sequenced, and analyzed to determine genetic diversity and population structure. A total of 126 (Port Victoria-38, Migori-38, Bungoma-22, and Kombewa-28) sequences of COII were used for population genetic analysis. Anopheles funestus had a high haplotype diversity (Hd = 0.97 to 0.98) but low nucleotide diversity (Π = 0.004 to 0.005). The neutrality test revealed negative Tajima's D and Fs values indicating an excess of low-frequency variation. This could be attributed to either population expansion or negative selection pressure across all the populations. No genetic or structural differentiation (Fst = -0.01) and a high level of gene flow (Gamma St, Nm = 17.99 to 35.22) were observed among the populations. Population expansion suggests the high adaptability of this species to various ecological requirements, hence sustaining its vectorial capacity and malaria transmission.
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Affiliation(s)
- Isaiah Debrah
- West Africa Centre for Cell Biology of Infectious Pathogen (WACCBIP), University of Ghana, Accra P.O. Box LG 54, Ghana
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homabay P.O. Box 199-40300, Kenya
| | - Kevin O. Ochwedo
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homabay P.O. Box 199-40300, Kenya
| | - Wilfred O. Otambo
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homabay P.O. Box 199-40300, Kenya
| | - Maxwell G. Machani
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu P.O. Box 20778-00202, Kenya
| | - Edwin O. Magomere
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homabay P.O. Box 199-40300, Kenya
| | - Shirley A. Onyango
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homabay P.O. Box 199-40300, Kenya
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California, Irvine, CA 92697, USA
| | - Linda E. Amoah
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra P.O. Box LG 581, Ghana
| | - Andrew K. Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu P.O. Box 20778-00202, Kenya
| | - Yaw A. Afrane
- Department of Medical Microbiology, University of Ghana Medical School, College of Health Sciences, University of Ghana, Accra P.O. Box 4236, Ghana
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California, Irvine, CA 92697, USA
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Onyango SA, Ochwedo KO, Machani MG, Olumeh JO, Debrah I, Omondi CJ, Ogolla SO, Lee MC, Zhou G, Kokwaro E, Kazura JW, Afrane YA, Githeko AK, Zhong D, Yan G. Molecular characterization and genotype distribution of thioester-containing protein 1 gene in Anopheles gambiae mosquitoes in western Kenya. Malar J 2022; 21:235. [PMID: 35948910 PMCID: PMC9364548 DOI: 10.1186/s12936-022-04256-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 08/03/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Evolutionary pressures lead to the selection of efficient malaria vectors either resistant or susceptible to Plasmodium parasites. These forces may favour the introduction of species genotypes that adapt to new breeding habitats, potentially having an impact on malaria transmission. Thioester-containing protein 1 (TEP1) of Anopheles gambiae complex plays an important role in innate immune defenses against parasites. This study aims to characterize the distribution pattern of TEP1 polymorphisms among populations of An. gambiae sensu lato (s.l.) in western Kenya. METHODS Anopheles gambiae adult and larvae were collected using pyrethrum spray catches (PSC) and plastic dippers respectively from Homa Bay, Kakamega, Bungoma, and Kisumu counties between 2017 and 2020. Collected adults and larvae reared to the adult stage were morphologically identified and then identified to sibling species by PCR. TEP1 alleles were determined in 627 anopheles mosquitoes using restriction fragment length polymorphisms-polymerase chain reaction (RFLP-PCR) and to validate the TEP1 genotyping results, a representative sample of the alleles was sequenced. RESULTS Two TEP1 alleles (TEP1*S1 and TEP1*R2) and three corresponding genotypes (*S1/S1, *R2/S1, and *R2/R2) were identified. TEP1*S1 and TEP1*R2 with their corresponding genotypes, homozygous *S1/S1 and heterozygous *R2/S1 were widely distributed across all sites with allele frequencies of approximately 80% and 20%, respectively both in Anopheles gambiae and Anopheles arabiensis. There was no significant difference detected among the populations and between the two mosquito species in TEP1 allele frequency and genotype frequency. The overall low levels in population structure (FST = 0.019) across all sites corresponded to an effective migration index (Nm = 12.571) and low Nei's genetic distance values (< 0.500) among the subpopulation. The comparative fixation index values revealed minimal genetic differentiation between species and high levels of gene flow among populations. CONCLUSION Genotyping TEP1 has identified two common TEP1 alleles (TEP1*S1 and TEP1*R2) and three corresponding genotypes (*S1/S1, *R2/S1, and *R2/R2) in An. gambiae s.l. The TEP1 allele genetic diversity and population structure are low in western Kenya.
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Affiliation(s)
- Shirley A Onyango
- Department of Zoological Sciences, School of Science and Technology, Kenyatta University, Nairobi, Kenya.,Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homa bay, Kenya
| | - Kevin O Ochwedo
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homa bay, Kenya.,Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | - Maxwell G Machani
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Julius O Olumeh
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homa bay, Kenya
| | - Isaiah Debrah
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homa bay, Kenya.,Department of Biochemistry, Cell and Molecular Biology, West Africa Centre for Cell Biology of Infectious Pathogen, University of Ghana, Accra, Ghana
| | - Collince J Omondi
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homa bay, Kenya.,Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | | | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, 92697, USA
| | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, 92697, USA
| | - Elizabeth Kokwaro
- Department of Zoological Sciences, School of Science and Technology, Kenyatta University, Nairobi, Kenya
| | - James W Kazura
- Center for Global Health and Diseases, Case Western Reserve University, LC 4983, Cleveland, OH, 44106, USA
| | - Yaw A Afrane
- Department of Medical Microbiology, Medical School, University of Ghana, University of Ghana, Accra, Ghana
| | - Andrew K Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, 92697, USA.
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, 92697, USA.
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Ochwedo KO, Ariri FO, Otambo WO, Magomere EO, Debrah I, Onyango SA, Orondo PW, Atieli HE, Ogolla SO, Otieno ACA, Mukabana WR, Githeko AK, Lee MC, Yan G, Zhong D, Kazura JW. Rare Alleles and Signatures of Selection on the Immunodominant Domains of Pfs230 and Pfs48/45 in Malaria Parasites From Western Kenya. Front Genet 2022; 13:867906. [PMID: 35656326 PMCID: PMC9152164 DOI: 10.3389/fgene.2022.867906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 04/25/2022] [Indexed: 01/27/2023] Open
Abstract
Background: Malaria elimination and eradication efforts can be advanced by including transmission-blocking or reducing vaccines (TBVs) alongside existing interventions. Key transmission-blocking vaccine candidates, such as Pfs230 domain one and Pfs48/45 domain 3, should be genetically stable to avoid developing ineffective vaccines due to antigenic polymorphisms. We evaluated genetic polymorphism and temporal stability of Pfs230 domain one and Pfs48/45 domain three in Plasmodium falciparum parasites from western Kenya. Methods: Dry blood spots on filter paper were collected from febrile malaria patients reporting to community health facilities in endemic areas of Homa Bay and Kisumu Counties and an epidemic-prone area of Kisii County in 2018 and 2019. Plasmodium speciation was performed using eluted DNA and real-time PCR. Amplification of the target domains of the two Pfs genes was performed on P. falciparum positive samples. We sequenced Pfs230 domain one on 156 clinical isolates and Pfs48/45 domain three on 118 clinical isolates to infer the levels of genetic variability, signatures of selection, genetic diversity indices and perform other evolutionary analyses. Results: Pfs230 domain one had low nucleotide diversity (π = 0.15 × 10-2) with slight variation per study site. Six polymorphic sites with nonsynonymous mutations and eight haplotypes were discovered. I539T was a novel variant, whereas G605S was nearing fixation. Pfs48/45 domain three had a low π (0.063 × 10-2), high conservation index, and three segregating sites, resulting in nonsynonymous mutation and four haplotypes. Some loci of Pfs230 D1 were in positive or negative linkage disequilibrium, had negative or positive selection signatures, and others (1813, 1955) and (1813, 1983) had a history of recombination. Mutated loci pairs in Pfs48/45 domain three had negative linkage disequilibrium, and some had negative and positive Tajima's D values with no history of recombination events. Conclusion: The two transmission blocking vaccine candidates have low nucleotide diversity, a small number of zone-specific variants, high nucleotide conservation index, and high frequency of rare alleles. With the near fixation a polymorphic site and the proximity of mutated codons to antibody binding epitopes, it will be necessary to continue monitoring sequence modifications of these domains when designing TBVs that include Pfs230 and Pfs48/45 antigens.
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Affiliation(s)
- Kevin O. Ochwedo
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya,Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Fredrick O. Ariri
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya,Department of Zoology, School of Physical and Biological Sciences, Maseno University, Kisumu, Kenya
| | - Wilfred O. Otambo
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya,Department of Zoology, School of Physical and Biological Sciences, Maseno University, Kisumu, Kenya
| | - Edwin O. Magomere
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya,Department of Biochemistry, Egerton University, Nakuru, Kenya
| | - Isaiah Debrah
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya,West Africa Centre for Cell Biology of Infectious Pathogen, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Accra, Ghana
| | - Shirley A. Onyango
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya,School of Zoological Sciences, Kenyatta University, Nairobi, Kenya
| | - Pauline W. Orondo
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Harrysone E. Atieli
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Sidney O. Ogolla
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Antony C. A. Otieno
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | - Wolfgang R. Mukabana
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya,Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Andrew K. Githeko
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya,Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California, Irvine, Irvine, CA, United States
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California, Irvine, Irvine, CA, United States
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California, Irvine, Irvine, CA, United States,*Correspondence: Daibin Zhong,
| | - James W. Kazura
- Centre for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, United States
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Otambo WO, Olumeh JO, Ochwedo KO, Magomere EO, Debrah I, Ouma C, Onyango P, Atieli H, Mukabana WR, Wang C, Lee MC, Githeko AK, Zhou G, Githure J, Kazura J, Yan G. Health care provider practices in diagnosis and treatment of malaria in rural communities in Kisumu County, Kenya. Malar J 2022; 21:129. [PMID: 35459178 PMCID: PMC9034626 DOI: 10.1186/s12936-022-04156-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 04/07/2022] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Accurate malaria diagnosis and appropriate treatment at local health facilities are critical to reducing morbidity and human reservoir of infectious gametocytes. The current study assessed the accuracy of malaria diagnosis and treatment practices in three health care facilities in rural western Kenya. METHODS The accuracy of malaria detection and treatment recommended compliance was monitored in two public and one private hospital from November 2019 through March 2020. Blood smears from febrile patients were examined by hospital laboratory technicians and re-examined by an expert microscopists thereafter subjected to real-time polymerase chain reaction (RT-PCR) for quality assurance. In addition, blood smears from patients diagnosed with malaria rapid diagnostic tests (RDT) and presumptively treated with anti-malarial were re-examined by an expert microscopist. RESULTS A total of 1131 febrile outpatients were assessed for slide positivity (936), RDT (126) and presumptive diagnosis (69). The overall positivity rate for Plasmodium falciparum was 28% (257/936). The odds of slide positivity was higher in public hospitals, 30% (186/624, OR:1.44, 95% CI = 1.05-1.98, p < 0.05) than the private hospital 23% (71/312, OR:0.69, 95% CI = 0.51-0.95, p < 0.05). Anti-malarial treatment was dispensed more at public hospitals (95.2%, 177/186) than the private hospital (78.9%, 56/71, p < 0.0001). Inappropriate anti-malarial treatment, i.e. artemether-lumefantrine given to blood smear negative patients was higher at public hospitals (14.6%, 64/438) than the private hospital (7.1%, 17/241) (p = 0.004). RDT was the most sensitive (73.8%, 95% CI = 39.5-57.4) and specific (89.2%, 95% CI = 78.5-95.2) followed by hospital microscopy (sensitivity 47.6%, 95% CI = 38.2-57.1) and specificity (86.7%, 95% CI = 80.8-91.0). Presumptive diagnosis had the lowest sensitivity (25.7%, 95% CI = 13.1-43.6) and specificity (75.0%, 95% CI = 50.6-90.4). RDT had the highest non-treatment of negatives [98.3% (57/58)] while hospital microscopy had the lowest [77.3% (116/150)]. Health facilities misdiagnosis was at 27.9% (77/276). PCR confirmed 5.2% (4/23) of the 77 misdiagnosed cases as false positive and 68.5% (37/54) as false negative. CONCLUSIONS The disparity in malaria diagnosis at health facilities with many slide positives reported as negatives and high presumptive treatment of slide negative cases, necessitates augmenting microscopic with RDTs and calls for Ministry of Health strengthening supportive infrastructure to be in compliance with treatment guidelines of Test, Treat, and Track to improve malaria case management.
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Affiliation(s)
- Wilfred Ouma Otambo
- grid.442486.80000 0001 0744 8172Department of Zoology, Maseno University, Kisumu, Kenya ,International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Julius O. Olumeh
- International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya ,grid.10604.330000 0001 2019 0495Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | - Kevin O. Ochwedo
- International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya ,grid.10604.330000 0001 2019 0495Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | - Edwin O. Magomere
- grid.8301.a0000 0001 0431 4443Department of Biochemistry and Molecular Biology, Egerton University, Njoro, Kenya
| | - Isaiah Debrah
- International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya ,grid.8652.90000 0004 1937 1485West Africa Centre for Cell Biology of Infectious Pathogen, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Accra, Ghana
| | - Collins Ouma
- grid.442486.80000 0001 0744 8172Department of Biomedical Sciences and Technology, Maseno University, Kisumu, Kenya
| | - Patrick Onyango
- grid.442486.80000 0001 0744 8172Department of Zoology, Maseno University, Kisumu, Kenya
| | - Harrysone Atieli
- International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Wolfgang R. Mukabana
- International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya ,grid.10604.330000 0001 2019 0495Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | - Chloe Wang
- grid.266093.80000 0001 0668 7243Depatment of Population Health and Disease Prevention, University of California, Irvine, CA USA
| | - Ming-Chieh Lee
- grid.266093.80000 0001 0668 7243Depatment of Population Health and Disease Prevention, University of California, Irvine, CA USA
| | - Andrew K. Githeko
- grid.33058.3d0000 0001 0155 5938Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Guofa Zhou
- grid.266093.80000 0001 0668 7243Depatment of Population Health and Disease Prevention, University of California, Irvine, CA USA
| | - John Githure
- International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - James Kazura
- grid.67105.350000 0001 2164 3847Centre for Global Health and Diseases, Case Western University Reserve, Cleveland, OH USA
| | - Guiyun Yan
- grid.266093.80000 0001 0668 7243Depatment of Population Health and Disease Prevention, University of California, Irvine, CA USA
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Ochwedo KO, Omondi CJ, Magomere EO, Olumeh JO, Debrah I, Onyango SA, Orondo PW, Ondeto BM, Atieli HE, Ogolla SO, Githure J, Otieno ACA, Githeko AK, Kazura JW, Mukabana WR, Guiyan Y. Hyper-prevalence of submicroscopic Plasmodium falciparum infections in a rural area of western Kenya with declining malaria cases. Malar J 2021; 20:472. [PMID: 34930283 PMCID: PMC8685826 DOI: 10.1186/s12936-021-04012-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 12/07/2021] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND The gold standard for diagnosing Plasmodium falciparum infection is microscopic examination of Giemsa-stained peripheral blood smears. The effectiveness of this procedure for infection surveillance and malaria control may be limited by a relatively high parasitaemia detection threshold. Persons with microscopically undetectable infections may go untreated, contributing to ongoing transmission to mosquito vectors. The purpose of this study was to determine the magnitude and determinants of undiagnosed submicroscopic P. falciparum infections in a rural area of western Kenya. METHODS A health facility-based survey was conducted, and 367 patients seeking treatment for symptoms consistent with uncomplicated malaria in Homa Bay County were enrolled. The frequency of submicroscopic P. falciparum infection was measured by comparing the prevalence of infection based on light microscopic inspection of thick blood smears versus real-time polymerase chain reaction (RT-PCR) targeting P. falciparum 18S rRNA gene. Long-lasting insecticidal net (LLIN) use, participation in nocturnal outdoor activities, and gender were considered as potential determinants of submicroscopic infections. RESULTS Microscopic inspection of blood smears was positive for asexual P. falciparum parasites in 14.7% (54/367) of cases. All of these samples were confirmed by RT-PCR. 35.8% (112/313) of blood smear negative cases were positive by RT-PCR, i.e., submicroscopic infection, resulting in an overall prevalence by RT-PCR alone of 45.2% compared to 14.7% for blood smear alone. Females had a higher prevalence of submicroscopic infections (35.6% or 72 out of 202 individuals, 95% CI 28.9-42.3) compared to males (24.2%, 40 of 165 individuals, 95% CI 17.6-30.8). The risk of submicroscopic infections in LLIN users was about half that of non-LLIN users (OR = 0.59). There was no difference in the prevalence of submicroscopic infections of study participants who were active in nocturnal outdoor activities versus those who were not active (OR = 0.91). Patients who participated in nocturnal outdoor activities and use LLINs while indoors had a slightly higher risk of submicroscopic infection than those who did not use LLINs (OR = 1.48). CONCLUSION Microscopic inspection of blood smears from persons with malaria symptoms for asexual stage P. falciparum should be supplemented by more sensitive diagnostic tests in order to reduce ongoing transmission of P. falciparum parasites to local mosquito vectors.
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Affiliation(s)
- Kevin O. Ochwedo
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Collince J. Omondi
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Edwin O. Magomere
- Department of Biochemistry and Molecular Biology, Egerton University, Njoro, Kenya
| | - Julius O. Olumeh
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Isaiah Debrah
- West Africa Centre for Cell Biology of Infectious Pathogen, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Accra, Ghana
| | - Shirley A. Onyango
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Pauline W. Orondo
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Benyl M. Ondeto
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Harrysone E. Atieli
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Sidney O. Ogolla
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - John Githure
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Antony C. A. Otieno
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | - Andrew K. Githeko
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - James W. Kazura
- Centre for Global Health and Diseases, Case Western Reserve University, Cleveland, OH USA
| | - Wolfgang R. Mukabana
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Yan Guiyan
- Program in Public Health, College of Health Sciences, University of California, Irvine, USA
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Onyango SA, Ochwedo KO, Machani MG, Omondi CJ, Debrah I, Ogolla SO, Lee MC, Zhou G, Kokwaro E, Kazura JW, Afrane YA, Githeko AK, Zhong D, Yan G. Genetic diversity and population structure of the human malaria parasite Plasmodium falciparum surface protein Pfs47 in isolates from the lowlands in Western Kenya. PLoS One 2021; 16:e0260434. [PMID: 34843560 PMCID: PMC8629314 DOI: 10.1371/journal.pone.0260434] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 11/10/2021] [Indexed: 11/23/2022] Open
Abstract
Plasmodium falciparum parasites have evolved genetic adaptations to overcome immune responses mounted by diverse Anopheles vectors hindering malaria control efforts. Plasmodium falciparum surface protein Pfs47 is critical in the parasite’s survival by manipulating the vector’s immune system hence a promising target for blocking transmission in the mosquito. This study aimed to examine the genetic diversity, haplotype distribution, and population structure of Pfs47 and its implications on malaria infections in endemic lowlands in Western Kenya. Cross-sectional mass blood screening was conducted in malaria endemic regions in the lowlands of Western Kenya: Homa Bay, Kombewa, and Chulaimbo. Dried blood spots and slide smears were simultaneously collected in 2018 and 2019. DNA was extracted using Chelex method from microscopic Plasmodium falciparum positive samples and used to genotype Pfs47 using polymerase chain reaction (PCR) and DNA sequencing. Thirteen observed haplotypes of the Pfs47 gene were circulating in Western Kenya. Population-wise, haplotype diversity ranged from 0.69 to 0.77 and the nucleotide diversity 0.10 to 0.12 across all sites. All the study sites displayed negative Tajima’s D values although not significant. However, the negative and significant Fu’s Fs statistical values were observed across all the study sites, suggesting population expansion or positive selection. Overall genetic differentiation index was not significant (FST = -0.00891, P > 0.05) among parasite populations. All Nm values revealed a considerable gene flow in these populations. These results could have important implications for the persistence of high levels of malaria transmission and should be considered when designing potential targeted control interventions.
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Affiliation(s)
- Shirley A. Onyango
- Department of Zoological Sciences, School of Science and Technology, Kenyatta University, Nairobi, Kenya
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homa Bay, Kenya
| | - Kevin O. Ochwedo
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homa Bay, Kenya
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | - Maxwell G. Machani
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Collince J. Omondi
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homa Bay, Kenya
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | - Isaiah Debrah
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homa Bay, Kenya
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Sidney O. Ogolla
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California, Irvine, California, United States of America
| | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California, Irvine, California, United States of America
| | - Elizabeth Kokwaro
- Department of Zoological Sciences, School of Science and Technology, Kenyatta University, Nairobi, Kenya
| | - James W. Kazura
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Yaw A. Afrane
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Accra, Ghana
| | - Andrew K. Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California, Irvine, California, United States of America
- * E-mail: (DZ); (GY)
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California, Irvine, California, United States of America
- * E-mail: (DZ); (GY)
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Debrah I, Afrane YA, Amoah LE, Ochwedo KO, Mukabana WR, Zhong D, Zhou G, Lee M, Onyango SA, Magomere EO, Atieli H, Githeko AK, Yan G. Larval ecology and bionomics of Anopheles funestus in highland and lowland sites in western Kenya. PLoS One 2021; 16:e0255321. [PMID: 34634069 PMCID: PMC8504749 DOI: 10.1371/journal.pone.0255321] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 09/16/2021] [Indexed: 11/18/2022] Open
Abstract
Background An. funestus is a major Afrotropical vector of human malaria. This study sought to investigate the larval ecology, sporozoite infection rates and blood meal sources of An. funestus in western Kenya. Methods Larval surveys were carried out in Bungoma (Highland) and Kombewa (lowland) of western Kenya. Aquatic habitats were identified, characterized, georeferenced and carefully examined for mosquito larvae and predators. Indoor resting mosquitoes were sampled using pyrethrum spray catches. Adults and larvae were morphologically and molecularly identified to species. Sporozoite infections and blood meal sources were detected using real-time PCR and ELISA respectively. Results Of the 151 aquatic habitats assessed, 62/80 (78%) in Bungoma and 58/71(82%) in Kombewa were positive for mosquito larvae. Of the 3,193 larvae sampled, An. funestus larvae constitute 38% (1224/3193). Bungoma recorded a higher number of An. funestus larvae (85%, 95%, CI, 8.722–17.15) than Kombewa (15%, 95%, CI, 1.33–3.91). Molecular identification of larvae showed that 89% (n = 80) were An. funestus. Approximately 59%, 35% and 5% of An. funestus larvae co-existed with An. gambiae s.l, Culex spp and An. coustani in the same habitats respectively. Of 1,221 An. funestus s.l adults sampled, molecular identifications revealed that An. funestus constituted 87% (n = 201) and 88% (n = 179) in Bungoma and Kombewa, respectively. The Plasmodium falciparum sporozoite rate of An. funestus in Bungoma and Kombewa was 2% (3/174) and 1% (2/157), respectively, and the human blood index of An. funestus was 84% (48/57) and 89% (39/44) and for Bungoma and Kombewa, respectively. Conclusion Man-made ponds had the highest abundance of An. funestus larvae. Multiple regression and principal component analyses identified the distance to the nearest house as the key environmental factor associated with the abundance of An. funestus larvae in aquatic habitats. This study serves as a guide for the control of An. funestus and other mosquito species to complement existing vector control strategies.
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Affiliation(s)
- Isaiah Debrah
- Department of Biochemistry, Cell and Molecular Biology, West Africa Centre for Cell Biology of Infectious Pathogen, University of Ghana, Accra, Ghana
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homabay, Kenya
| | - Yaw A. Afrane
- Department of Medical Microbiology, University of Ghana Medical School, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Linda E. Amoah
- Department of Biochemistry, Cell and Molecular Biology, West Africa Centre for Cell Biology of Infectious Pathogen, University of Ghana, Accra, Ghana
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Kevin O. Ochwedo
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homabay, Kenya
| | | | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, United States of America
| | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, United States of America
| | - Ming‑Chieh Lee
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, United States of America
| | - Shirley A. Onyango
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homabay, Kenya
| | - Edwin O. Magomere
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homabay, Kenya
| | - Harrysone Atieli
- Sub-Saharan Africa International Centre of Excellence for Malaria Research, Homabay, Kenya
| | | | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, United States of America
- * E-mail:
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