Raphael Okoth

ORCID: 0000-0003-3811-433X
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About
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Research Areas
  • Malaria Research and Control
  • Mosquito-borne diseases and control
  • Computational Drug Discovery Methods
  • vaccines and immunoinformatics approaches
  • Escherichia coli research studies
  • Bacterial biofilms and quorum sensing
  • Parasites and Host Interactions
  • Hemoglobinopathies and Related Disorders
  • Antimicrobial Resistance in Staphylococcus
  • Drug-Induced Hepatotoxicity and Protection
  • Vector-borne infectious diseases
  • Bacterial Identification and Susceptibility Testing
  • Travel-related health issues
  • Hepatitis B Virus Studies
  • Zoonotic diseases and public health
  • Trypanosoma species research and implications
  • Drug Transport and Resistance Mechanisms
  • Viral gastroenteritis research and epidemiology
  • Global Maternal and Child Health
  • Hepatitis Viruses Studies and Epidemiology
  • Blood groups and transfusion

Kenya Medical Research Institute
2020-2025

United States Army Medical Research Directorate - Africa
2019-2025

The epidemiology and severity of non-falciparum malaria in endemic settings has garnered little attention. We aimed to characterise the prevalence, interaction, clinical risk factors, temporal trends Plasmodium species among symptomatic individuals presenting at health-care facilities Kenya.We diagnosed analysed infecting (Plasmodium falciparum, ovale curtisi, wallikeri, malariae) via PCR samples collected between March 1, 2008, Dec 31, 2016, from six hospitals located different regions...

10.1016/s2666-5247(21)00009-4 article EN cc-by-nc-nd The Lancet Microbe 2021-03-03

<title>Abstract</title> <bold>Background</bold> This study evaluated the polymorphisms of <italic>Pfk13</italic>gene alongside other malaria drug resistance markers in clinical samples from eight geographically distinct locations Kenya to determine prevalence mutations associated with partial artemisinin resistance. <bold>Methods</bold> Between 2018 and 2024, blood individuals symptoms uncomplicated at hospitals four five transmission zones were sequenced for single nucleotide (SNPs)...

10.21203/rs.3.rs-6214166/v1 preprint EN cc-by Research Square (Research Square) 2025-03-17

Assessing the infectious reservoir is critical in malaria control and elimination strategies. We conducted a longitudinal epidemiological study high-malaria-burden region Kenya to characterize transmission an asymptomatic population.488 participants encompassing all ages 120 households within 30 clusters were followed for 1 year with monthly sampling. Malaria was diagnosed by microscopy molecular methods. Transmission potential gametocytemic assessed using direct skin and/or membrane...

10.1093/cid/ciac527 article EN cc-by-nc-nd Clinical Infectious Diseases 2022-06-29

Abstract Background Dihydroartemisinin-piperaquine (DHA-PPQ) is an alternative first-line antimalarial to artemether-lumefantrine in Kenya. However, recent reports on the emergence of PPQ resistance Southeast Asia threaten its continued use Kenya and Africa. In line with policy deployment DHA-PPQ, it imperative monitor susceptibility Kenyan parasites other antimalarials. Methods Parasite isolates collected between 2008 2021 from individuals naturally acquired P. falciparum infections...

10.1186/s12916-022-02652-2 article EN cc-by BMC Medicine 2022-11-18

Abstract Background Malaria and schistosomiasis present considerable disease burden in tropical sub-tropical areas severity is worsened by co-infections where both diseases are endemic. Although pathogenesis of these infections separately well studied, there limited information on the pathogenic mechanisms clinical outcomes co-infections. In this study, we investigated prevalence malaria co-infections, hematologic blood chemistry abnormalities asymptomatic adults a rural fishing community...

10.1186/s12879-021-06626-2 article EN cc-by BMC Infectious Diseases 2021-09-09

Introduction: diarrheal infections in young children below five years and food animals are caused by diarrheagenic Escherichia coli strains. The study focused on understanding the association between DEC pathotypes to establish possibility of zoonotic transmission.

10.11604/pamj.2024.47.25.41197 article EN cc-by Pan African Medical Journal 2024-01-01

Malaria drug resistance is a global public health concern. Though parasite mutations have been associated with resistance, other factors could influence the resistance. A robust surveillance system required to monitor and help contain This study established role of travel gender in dispersion chloroquine resistant genotypes malaria epidemic zones Kenya. total 1,776 individuals presenting uncomplicated at hospitals selected from four transmission Kenya between 2008 2014 were enrolled...

10.7717/peerj.8082 article EN cc-by PeerJ 2020-03-12

Single nucleotide polymorphisms (SNPs) in the Plasmodium falciparum multi-drug resistance protein 1 ( Pfmrp1 ) gene have previously been reported to confer Artemisinin-based Combination Therapies (ACTs) Southeast Asia. A total of 300 samples collected from six sites between 2008 and 2019 under an ongoing malaria drug sensitivity patterns Kenya study were evaluated for presence SNPs at codons: H191Y, S437A, I876V, F1390I using Agena MassARRAY® platform. Each isolate was further tested against...

10.1371/journal.pone.0298585 article EN public-domain PLoS ONE 2024-06-20

Purpose . Data on the clonal distribution of Staphylococcus aureus in Africa are scanty, partly due to high costs and long turnaround times imposed by conventional genotyping methods such as spa multilocus sequence typing (MLST), which means there is a need for alternative approaches. This study evaluated discriminatory power, cost time required Kenyan staphylococcal isolates using iPlex MassARRAY compared methods. Methodology. Fifty-four clinical S. from three counties were characterized...

10.1099/acmi.0.000018 article EN cc-by-nc Access Microbiology 2019-05-01

This study examined the treatment response of mixed vs single-species Plasmodium falciparum infections to artemisinin-based combination therapies (ACTs).A total 1211 blood samples collected on days 0, 7, 14, 21, 28, 35, and 42 from 173 individuals enrolled in two randomized ACT efficacy studies were tested for malaria using 18s ribosomal RNA-based real-time polymerase chain reaction. All recurrent parasitemia characterized species composition time reinfection during 42-day follow-up compared...

10.1016/j.ijid.2023.04.008 article EN cc-by-nc-nd International Journal of Infectious Diseases 2023-04-14

The ABO blood groups consist of A, B, and H carbohydrate antigens, which regulate protein activities during malaria infection in humans. Understanding the interplay between parasite group antigens is essential understanding new interventions to reduce global burden malaria. This study assessed among individuals with varying seeking treatment at selected hospitals Kenya.A total 366 samples from an ongoing surveillance were diagnosed for by microscopy further typed using grouping. Age sex...

10.1186/s12936-022-04251-1 article EN cc-by Malaria Journal 2022-09-01

The impact of pre-existing immunity on the efficacy artemisinin combination therapy is largely unknown. We performed in-depth profiling serological responses in a therapeutic study [comparing artesunate-mefloquine (ASMQ) and artemether-lumefantrine (AL)] using proteomic microarray. Responses to over 200 Plasmodium antigens were significantly associated with ASMQ treatment outcome but not AL. used machine learning develop predictive models based immunoprofile data. predict for high (72-85%)...

10.3389/fmed.2022.991807 article EN cc-by Frontiers in Medicine 2022-10-13

Background: Diarrheal disease remains one of the leading causes deaths in children below five years age. The risk factors associated with diarrhea include poor hygiene practices such as open defecation and consumption contaminated water food. However, exposure domestic animal is equally a potential factor for children. Methodology: We characterized animal-related exposures subset households (n=73) by collecting faecal samples from 150 diarrhoea 100 food animals (30 cattle, 30 chicken, 25...

10.4314/ajcem.v25i4.7 article EN African Journal of Clinical and Experimental Microbiology 2024-10-07

<ns3:p><ns3:bold>Background: </ns3:bold>The emergence of artemisinin resistance in South East Asia calls for urgent discovery new drug compounds that have antiplasmodial activity. Unlike the classical compound screening methods, rational approach involving targeted is less cumbersome and therefore key innovation compounds. <ns3:italic>Plasmodium falciparum</ns3:italic> (Pf) utilizes process host erythrocyte remodeling using Plasmodium-helical interspersed sub-telomeric domain (PHIST)...

10.12688/f1000research.26756.1 preprint EN cc-by F1000Research 2020-10-23

<ns5:p><ns5:bold>Background: </ns5:bold>The emergence of artemisinin resistance in South East Asia calls for urgent discovery new drug compounds that have antiplasmodial activity. Unlike the classical compound screening methods, rational approach involving targeted is less cumbersome and therefore key innovation compounds. <ns5:italic>Plasmodium falciparum</ns5:italic> (Pf) utilizes process host erythrocyte remodeling using Plasmodium-helical interspersed sub-telomeric domain (PHIST)...

10.12688/f1000research.26756.2 preprint EN cc-by F1000Research 2022-04-29

Abstract Background The epidemiology and severity of non-falciparum malaria in endemic settings has garnered limited attention. We aimed to characterize the prevalence, interaction, clinical risk factors temporal trends Kenya. Methods diagnosed analyzed infecting species via PCR 2027 samples collected between 2008 2016. Descriptive statistics were used describe prevalence distribution Plasmodium species. A statistical model was designed for estimating frequency assessing inter-species...

10.1101/2019.12.28.19015941 preprint EN cc-by medRxiv (Cold Spring Harbor Laboratory) 2020-01-02

Abstract The role of humoral immunity on the efficacy artemisinin combination therapy (ACT) has not been investigated, yet naturally acquired is key determinant antimalarial therapeutic response. We conducted a study in high transmission settings western Kenya, which showed artesunate-mefloquine (ASMQ) and dihydroartemisinin-piperaquine (DP) were more efficacious than artemether-lumefantrine (AL). To investigate underlying prophylactic mechanism, we compared broad range immune responses...

10.1101/2020.08.12.248724 preprint EN bioRxiv (Cold Spring Harbor Laboratory) 2020-08-12

HIV and malaria coinfection impacts disease management clinical outcomes. This study investigated hematologic abnormalities in malaria-asymptomatic people living with (PLHIV) regions differing transmission.Study participants were enrolled the African Cohort Study: two sites Kenya, one Uganda, Nigeria. Data was collected at enrollment every 6 months. Logistic regression estimated odds ratios for associations between HIV/malaria status anemia, thrombocytopenia, leucopenia.Samples from 1587 or...

10.1016/j.ijid.2023.09.018 article EN cc-by-nc-nd International Journal of Infectious Diseases 2023-10-01

Abstract Background Data on the clonal distribution of Staphylococcus aureus in Africa is scanty, partly due to high costs and long turnaround times imposed by conventional genotyping methods such as spa multilocus sequence typing (MLST) warranting need for alternative approaches. This study applied evaluated accuracy, cost time using iPlex massARRAY method Kenyan staphylococcal isolates. Methods Fifty four clinical S. isolates from three counties were characterized massARRAY, MLST methods....

10.1101/395079 preprint EN cc-by-nc-nd bioRxiv (Cold Spring Harbor Laboratory) 2018-08-20

Non-pregnant women clear parasites faster than pregnant. Non-immune environment in pregnant may select for parasite populations associated with artemisinin resistance.  Objective: To identify antimalarial drugs resistance polymorphisms expressed P. falciparum versus non-pregnant Kenya. Methods Blood samples were collected at hours 0, 8, 24; days 7 and 28 from 75 malaria positive women. Arm1(pregnant second trimester), arm2(pregnant third trimester) Arm3(non-pregnant). Samples diagnosed...

10.21955/aasopenres.1114904.1 article EN 2019-08-05

Background: As studies continue to confirm the rising frequency of mixed Plasmodium species infections, there is little data on response non-falciparum Artemisinin Combination Therapies (ACTs) which a critical tool for malaria elimination. This study compared therapeutic P. falciparum single infection versus ACTs.Methods: A total 1211 blood samples collected days 0, 7, 14, 21, 28, 35, and day 42 from 173 individuals out 236 enrolled in an ACT efficacy between 2013 2015 were diagnosed using...

10.2139/ssrn.4225657 article EN SSRN Electronic Journal 2022-01-01
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