Irene Onyango

United States Army Medical Research Directorate - Africa

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Ben Andagalu

United States Army Medical Research Directorate - Africa

Hoseah M. Akala

United States Army Medical Research Directorate - Africa

Nicola Mulder

University of Cape Town

Washingtone Ochieng

Nairobi Hospital

Javan Okendo

National Human Genome Research Institute

Clarisse Musanabaganwa

Ministry of Health

Dennis W. Juma

Kenya Medical Research Institute

Agnes C. Cheruiyot

United States Army Medical Research Directorate - Africa

Bernhards Ogutu

Strathmore University

Edwin Kamau

Walter Reed National Military Medical Center

Cooperative Institutions

Kenya Medical Research Institute

United States Army Medical Research Directorate - Africa

Maseno University

Walter Reed Army Institute of Research

Mpala Research Center and Wildlife Foundation

Jomo Kenyatta University of Agriculture and Technology

United States Army

University of Nairobi

Program for Appropriate Technology in Health

U.S. President's Malaria Initiative

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Analysis of Within-host Evolution of Plasmodium falciparum during treatment with Artemisinin Combination TherapiesAnalysis of Within-host Evolution of Plasmodium falciparum during treatment with Artemisinin Combination Therapies

Figshare (2019)

Javan Okendo Irene Onyango Clarisse Musanabaganwa Washingtone Ochieng Ben Andagalu

The supporting information for the study titled "Analysis of withi-host Evolution of Plasmodium falciparum during treatment with Artemisinin Combination Therapies"

Combination therapy

Plasmodium (life cycle)

10.6084/m9.figshare.9905138.v7

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International Journal of Mosquito Research (2020)

Samuel Kabochi Benson Mwangi Michael M. Gicheru George Michuki Irene Onyango

Mosquito ecology is influenced by wetness in the environment.In 2011-2014, a rise in waters of Lake Baringo resulted in unprecedented flooding that inundated over 88km 2 of the shoreline.A longitudinal study carried out from October 2012-October 2013 assessed mosquito abundance and diversity in two habitats.A total of 386,624 mosquitoes were captured, 89% from flooded shoreline and 11% from swampy habitat.Family Culicinae constituted 10 genera.Mansonia dominated the catches with 98% from flooded shoreline and swampy habitat 2%.Genetic sequences of Aedes albopictus species was identified and reported for the first time in the basin.Diversity index was higher in swampy habitat (Simpson Diversity Index=0.56), compared to flooded shoreline (Simpson diversity index =0.13).Future recurring floods will result in drastic changes of the ecology and could lead to emergence and reemergence of more species.

10.22271/23487941.2020.v7.i6.a

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Figshare (2019)

Javan Okendo Irene Onyango Clarisse Musanabaganwa Washingtone Ochieng Ben Andagalu

The supporting information for the study titled "Analysis of withi-host Evolution of Plasmodium falciparum during treatment with Artemisinin Combination Therapies"

Plasmodium (life cycle)

10.6084/m9.figshare.9905138.v6

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Analysis of Major Genome Loci Underlying Artemisinin Resistance and pfmdr1 Copy Number in pre- and post-ACTs in Western Kenya

Scientific Reports (2015)

Bidii S. Ngalah Luiser A. Ingasia Agnes C. Cheruiyot Lorna J. Chebon Dennis W. Juma

Abstract Genetic analysis of molecular markers is critical in tracking the emergence and/or spread of artemisinin resistant parasites. Clinical isolates collected in western Kenya pre- and post- introduction of artemisinin combination therapies (ACTs) were genotyped at SNP positions in regions of strong selection signatures on chromosome 13 and 14, as described in Southeast Asia (SEA). Twenty five SNPs were genotyped using Sequenom MassArray and pfmdr 1 gene copy number by real-time PCR. Parasite clearance half-life and in vitro drug sensitivity testing were performed using standard methods. One hundred twenty nine isolates were successfully analyzed. Fifteen SNPs were present in pre-ACTs isolates and six in post-ACTs. None of the SNPs showed association with parasite clearance half-life. Post-ACTs parasites had significantly higher pfmdr 1 copy number compared to pre-ACTs. Seven of eight parasites with multiple pfmdr 1 were post-ACTs. When in vitro IC 50 s were compared for parasites with single vs. multiple gene copies, only amodiaquine and piperaquine reached statistical significance. Data showed SNPs on chromosome 13 and 14 had different frequency and trend in western Kenya parasites compared SEA. Increase in pfmdr 1 gene copy is consistent with recent studies in African parasites. Data suggests genetic signature of artemisinin resistance in Africa might be different from SEA.

Piperaquine

SNP

SNP array

10.1038/srep08308

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Citations (31)

The Walter Reed Project, Kisumu Field Station: Impact of Research on Malaria Policy, Management, and Prevention

American Journal of Tropical Medicine and Hygiene (2024)

Peter Sifuna Michal Mbinji Tina O. Lucas Irene Onyango Hoseah M. Akala

ABSTRACT. The Walter Reed Project is a collaboration between the Walter Reed Army Institute of Research of the United States Department of Defense and the Kenya Medical Research Institute. The Kisumu field station, comprising four campuses, has until recently been devoted primarily to research on malaria countermeasures. The Kombewa Clinical Research Center is dedicated to conducting regulated clinical trials of therapeutic and vaccine candidates in development. The center’s robust population-based surveillance platform, along with an active community engagement strategy, guarantees consistent recruitment and retention of participants in clinical trials. The Malaria Diagnostic Center, backed by WHO-certified microscopists and a large malaria blood film collection, champions high-quality malaria diagnosis and strict quality assurance through standardized microscopy trainings. The Malaria Drug Resistance Laboratory leverages cutting-edge technology such as real-time Polymerase Chain Reaction (qPCR) to conduct comprehensive research on resistance markers and obtain information on drug efficacy. The laboratory has been working on validating artemisinin resistance markers and improving tracking methods for current and future antimalarial compounds. Finally, the Basic Science Laboratory employs advanced genomic technology to examine endpoints such as immunogenicity and genomic fingerprinting for candidate drugs and vaccine efficacy. Herein, we examine the site’s significant contributions to malaria policy, management, and prevention practices in Kenya and around the world.

Malaria prevention

10.4269/ajtmh.23-0115

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Therapeutic response to artemisinin combination therapies among individuals with Plasmodium falciparum single infection vs mixed Plasmodium species infections: a retrospective posthoc analysis in Kisumu County, western Kenya

International Journal of Infectious Diseases (2023)

Gladys Chemwor Ben M. Andagalu Irene Onyango Benjamin Opot Raphael Okoth

This study examined the treatment response of mixed vs single-species Plasmodium falciparum infections to artemisinin-based combination therapies (ACTs).A total of 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 were characterized for Plasmodium species composition and time to reinfection during 42-day follow-up compared across ACTs.Day 0 samples had 71.1% (116/163) single P. falciparum infections and 28.2% (46/163) coinfections. A total of 54.0% (88/163) of individuals tested positive for Plasmodium at least once between days 7-42. A total of 19.3% (17/88) of individuals with recurrent infections were infected with a different Plasmodium species than observed at day 0, with 76.5% (13/17) of these "hidden" infections appearing after clearing P. falciparum present at day 0. Artesunate-mefloquine (16.4 hours) and dihydroartemisinin-piperaquine (17.6 hours) had increased clearance rates over artemether-lumefantrine (21.0 hours). Dihydroartemisinin-piperaquine exhibited the longest duration of reinfection prophylaxis. Cure rates were comparable across each species composition.No differences in clearance rates were found depending on whether the infection contained species other than P. falciparum. Significantly longer durations of protection were observed for individuals treated with dihydroartemisinin-piperaquine.

Piperaquine

Dihydroartemisinin

Artesunate

10.1016/j.ijid.2023.04.008

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Citations (2)

Analysis of Within-host Evolution of Plasmodium falciparum during treatment with Artemisinin Combination Therapies

Figshare (2019)

Javan Okendo Irene Onyango Clarisse Musanabaganwa Washingtone Ochieng Ben Andagalu

The supporting information for the study titled "Analysis of withi-host Evolution of Plasmodium falciparum during treatment with Artemisinin Combination Therapies"

10.6084/m9.figshare.9905138.v4

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Mosquitoes Composition, Abundance and Distribution In Swampy and Flooded Shoreline Habitats of Lake Baringo, Kenya, During a Period of Extreme Flooding (2012-2013)

International Journal of Mosquito Research (2020)

Samuel Kamau Kabochi Benson Mwangi Michael M. Gicheru George Michuki Irene Onyango

Mosquito ecology is influenced by wetness in the environment. In 2011-2014, a rise in waters of Lake Baringo resulted in unprecedented flooding that inundated over 88km2 of the shoreline. A longitudinal study carried out from October 2012-October 2013 assessed mosquito abundance and diversity in two habitats. A total of 386,624 mosquitoes were captured, 89% from flooded shoreline and 11% from swampy habitat. Family Culicinae constituted 10 genera. Mansonia dominated the catches with 98% from flooded shoreline and swampy habitat 2%. Genetic sequences of Aedes albopictus species was identified and reported for the first time in the basin. Diversity index was higher in swampy habitat (Simpson Diversity Index=0.56), compared to flooded shoreline (Simpson diversity index =0.13). Future recurring floods will result in drastic changes of the ecology and could lead to emergence and re-emergence of more species.

Diversity index

Mansonia

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Innate immune responses among hiv-1 highly exposed seronegative (hesn) individuals to a liveattenuated influenza vaccine as a model for mucosal viral infection

Irene Onyango

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Analysis of Within-host Evolution of Plasmodium falciparum during treatment with Artemisinin Combination Therapies

Figshare (2019)

Javan Okendo Irene Onyango Clarisse Musanabaganwa Washingtone Ochieng Ben Andagalu

The supporting information for the study titled "Analysis of withi-host Evolution of Plasmodium falciparum during treatment with Artemisinin Combination Therapies"

10.6084/m9.figshare.9905138

Cite

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