Publications by authors named "Kosgei J"

Importance: Nonresponse to hepatitis B vaccine is common among people with HIV, resulting in vulnerability to infection with hepatitis B virus (HBV).

Objective: To compare the seroprotection response achieved with a 2-dose (noninferiority, 10% margin) and a 3-dose hepatitis B vaccine with a cytosine phosphoguanine adjuvant (HepB-CpG vaccine) vs a conventional 3-dose hepatitis B vaccine with an aluminum hydroxide adjuvant (HepB-alum vaccine) in people with HIV and prior nonresponse to HepB-alum vaccine.

Design, Setting, And Participants: This phase 3, open-label, randomized clinical trial included people with HIV receiving antiretroviral therapy (CD4 cell count ≥100 cells/μL and HIV RNA <1000 copies/mL) without past or present serological evidence of having HBV or a response to hepatitis B vaccine.

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Introduction: Despite the increasing availability of prevention tools like pre-exposure prophylaxis (PrEP), HIV incidence remains disproportionately high in sub-Saharan Africa. We examined PrEP awareness, uptake and persistence among participants enrolling into an HIV incidence cohort in Kenya.

Methods: We used cross-sectional enrolment data from the Multinational Observational Cohort of HIV and other Infections (MOCHI) in Homa Bay and Kericho, Kenya.

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Article Synopsis
  • Malaria continues to be a major health threat in sub-Saharan Africa, causing 90% of malaria-related deaths, prompting the search for new vector control methods due to issues with current insecticides like resistance and environmental harm.
  • The study tested the insecticidal effects of (+)-usnic acid (UA) on Anopheles gambiae mosquitoes by mixing it with toxic sugar bait and observing mortality rates over time.
  • Results showed that a concentration of 15 mg/ml UA led to a 50% mortality rate in mosquitoes within just 4 hours, although the effectiveness decreased with longer exposure times.
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Background: Long-acting injectable cabotegravir and rilpivirine is licensed for individualised treatment of HIV-1 infection in resource-rich settings. Additional evidence is required to support use in African treatment programmes where demographic factors, viral subtypes, previous treatment, and delivery and monitoring approaches differ. The aim of this study was to determine whether switching to long-acting therapy with injections every 8 weeks is non-inferior to daily oral therapy in Africa.

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Background: Shorter prophylactic vaccine schedules may offer more rapid protection against Ebola in resource-limited settings.

Methods: This randomized, observer-blind, placebo-controlled, phase 2 trial conducted in 5 sub-Saharan African countries included people without human immunodeficiency virus (HIV) (PWOH, n = 249) and people with HIV (PWH, n = 250). Adult participants received 1 of 2 accelerated Ebola vaccine regimens (MVA-BN-Filo, Ad26.

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Article Synopsis
  • The study evaluates various mosquito sampling methods, including UV light traps, CDC light traps, and Prokopack aspiration, against the traditional human landing catches (HLC) in Kenya to address safety and efficacy.
  • Out of 5,370 Anopheles mosquitoes collected, the majority were An. funestus sensu lato, with a notable infection prevalence of 3.1% found only in this species.
  • Indoor aspiration proved to be the most effective method for capturing An. funestus compared to light traps, while UV light traps significantly outperformed HLC outdoors for collecting various Anopheles species.
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Background: Spatial repellents (SR) may complement current vector control tools and provide additional coverage when people are not under their bednets or are outdoors. Here we assessed the efficacy of a metofluthrin-based SR in reducing exposure to pyrethroid-resistant Anopheles funestus in Siaya County, western Kenya.

Methods: Metofluthrin was vaporized using an emanator configured to a liquid petroleum gas (LPG) canister, placed inside experimental huts (phase 1) or outdoors (phase 2), and evaluated for reductions in human landing rate, density, knockdown and mortality rates of An.

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Background: Children in Kenya spend a substantial amount of time at school, including at dawn and dusk when mosquitoes are active. With changing vector behaviour towards early morning biting, it is important to determine whether there is an additional risk of transmission in schools. This study sought to understand whether late morning biting by Anopheles funestus, previously documented in households in western Kenya, was replicated in schools.

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Attractive Targeted Sugar Baits (ATSB) have been demonstrated to result in significant reductions in malaria vector numbers in areas of scarce vegetation cover such as in Mali and Israel, but it is not clear whether such an effect can be replicated in environments where mosquitoes have a wide range of options for sugar resources. The current study evaluated the attractiveness of the predominant flowering plants of Asembo Siaya County, western Kenya in comparison to an ATSB developed by Westham Co. Sixteen of the most common flowering plants in the study area were selected and evaluated for relative attractiveness to malaria vectors in semi-field structures.

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Article Synopsis
  • Attractive targeted sugar baits (ATSBs) utilize the natural sugar-feeding habits of mosquitoes, particularly Anopheles species, as a method for vector control.
  • A study conducted in western Kenya found that 15.7% of the collected mosquitoes had fed on natural sugars, with males generally having a higher sugar-feeding rate than females, especially in the Anopheles funestus species.
  • The results indicate that mosquitoes consistently seek sugar meals at different life stages and locations, highlighting the potential for using ATSBs in mosquito population management.
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Unlabelled: We followed 54 infants with in utero HIV after initiating very early antiretroviral treatment. At weeks 24 and 48, ≥80% had CD4 ≥1500 cells/mm3 and CD4% ≥25%. Routine Pneumocystis jirovecii pneumonia prophylaxis in the first year of life may not be necessary for all very early treated infants.

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The responses of small-scale coastal fisheries to pauses in effort and trade are an important test of natural resource management theories with implications for the many challenges of managing common-pool resources. Three Covid-19 curfews provided a natural experiment to evaluate fisheries responses adjacent a marine reserve and in a management system that restricted small-mesh drag nets. Daily catch weights in ten fish landings were compared before and after the curfew period to test the catch-only hypothesis that the curfew would reduce effort and increase catch per unit effort, per area yields, and incomes.

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Background: Spatial repellents are widely used for prevention of mosquito bites and evidence is building on their public health value, but their efficacy against malaria incidence has never been evaluated in Africa. To address this knowledge gap, a trial to evaluate the efficacy of Mosquito Shield™, a spatial repellent incorporating transfluthrin, was developed for implementation in Busia County, western Kenya where long-lasting insecticidal net coverage is high and baseline malaria transmission is moderate to high year-round.

Methods: This trial is designed as a cluster-randomized, placebo-controlled, double-blinded clinical trial.

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Define the clinical presentation of acute human immunodeficiency virus infection (AHI) among men and women from 2 continents to create a clinical scoring algorithm.Comparison of incident sign and symptom between those with and without AHI.At-risk human immunodeficiency virus (HIV) negative men and women in Thailand, Kenya, Tanzania, and Uganda underwent twice-weekly testing for HIV.

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Background: HIV protease inhibitors anti-Plasmodium falciparum activity in adults remains uncertain.

Methods: Adults with HIV CD4+ counts >200 cells/mm3 starting antiretroviral therapy (ART) with P. falciparum subclinical parasitemia (Pf SCP) were randomized 1:1 to (step 1) protease inhibitor lopinavir/ritonavir (LPV/r)-based (arm A) or nonnucleoside reverse transcriptase inhibitor (nNRTI)-based ART (arm B) for 15 days.

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Identifying whether viral features present in acute HIV-1 infection predetermine the development of neutralization breadth is critical to vaccine design. Incorporating such features in vaccine antigens could initiate cross-reactive antibody responses that could sufficiently protect vaccinees from HIV-1 infection despite the uniqueness of each founder virus. To understand the relationship between Env determinants and the development of neutralization breadth, we focused on 197 individuals enrolled in two cohorts in Thailand and East Africa (RV144 and RV217) and followed since their diagnosis in acute or early HIV-1 infection.

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Background: Malaria vector control has been implemented chiefly through indoor interventions targeting primary vectors resulting in population declines-pointing to a possible greater proportional contribution to transmission by secondary malaria vectors with their predominant exophagic and exophilic traits. With a historical focus on primary vectors, there is paucity of data on secondary malaria vectors in many countries in Africa. This study sought to determine the species compositions and bionomic traits, including proportions infected with Plasmodium falciparum and phenotypic insecticide resistance, of secondary vectors in three sites with high malaria transmission in Kisumu County, western Kenya.

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The host decoy trap (HDT) is a surveillance trap that presents a combination of heat, visual and odour stimuli to attract bloodmeal-seeking mosquitoes. Here we employed a semi-field study to demonstrate the role of the visual attributes present on the HDT on the effectiveness of Aedes aegypti capture. Our results show that the HDT is an effective means of capturing Ae.

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Antiretroviral therapy (ART) can impact assays used for cross-sectional HIV incidence testing, causing inaccurate HIV incidence estimates. We evaluated the relationship between the timing of ART initiation and the performance of two serologic HIV incidence assays. We analyzed 302 samples from 55 individuals from the RV217 cohort (Early Capture HIV Cohort Study).

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Article Synopsis
  • The study investigates treatment strategies for AIDS-associated Kaposi sarcoma in low-resource settings, focusing on advanced cases in HIV-positive individuals across several African countries.
  • Participants were randomly assigned to receive one of three treatments combined with antiretroviral therapy, with the aim of examining progression-free survival (PFS) over 48 weeks.
  • The trial was halted early as both investigational treatments (bleomycin/vincristine and etoposide) demonstrated inferior outcomes compared to the control treatment (paclitaxel), which had significantly better PFS rates.
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Background: Understanding the interactions between increased insecticide resistance and resting behaviour patterns of malaria mosquitoes is important for planning of adequate vector control. This study was designed to investigate the resting behavior, host preference and rates of Plasmodium falciparum infection in relation to insecticide resistance of malaria vectors in different ecologies of western Kenya.

Methods: Anopheles mosquito collections were carried out during the dry and rainy seasons in Kisian (lowland site) and Bungoma (highland site), both in western Kenya using pyrethrum spray catches (PSC), mechanical aspiration (Prokopack) for indoor collections, clay pots, pit shelter and Prokopack for outdoor collections.

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Mucosa-associated invariant T (MAIT) cell loss in chronic HIV-1 infection is a significant insult to antimicrobial immune defenses. Here we investigate the response of MAIT cells during acute HIV-1 infection utilizing the RV217 cohort with paired longitudinal pre- and post-infection samples. MAIT cells are activated and expand in blood and mucosa coincident with peak HIV-1 viremia, in a manner associated with emerging microbial translocation.

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Background: Patients living with human immunodeficiency virus (PLWH) with low CD4 counts are at high risk for immune reconstitution inflammatory syndrome (IRIS) and death at antiretroviral therapy (ART) initiation.

Methods: We investigated the clinical impact of IRIS in PLWH and CD4 counts <100 cells/μL starting ART in an international, prospective study in the United States, Thailand, and Kenya. An independent review committee adjudicated IRIS events.

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Background: Malaria vector control is dependent on chemical insecticides applied to walls by indoor residual spraying or on long-lasting insecticidal nets. The emergence and spread of insecticide resistance in major malaria vectors may compromise malaria control and elimination efforts. The aim of this study was to estimate a diagnostic dose for chlorfenapyr (class: pyrrole) and clothianidin (class: neonicotinoid) and assess the baseline susceptibility of three major Anopheles malaria vectors of western Kenya to these two insecticides.

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Acute HIV-1 infection is characterized by high viremia and massive depletion of CD4 T cells throughout all tissue compartments. During this time the latent viral reservoir is established but the dynamics of memory CD4 T cell subset development, their infectability and influence on disease progression during acute HIV-1 infection has not been carefully described. We therefore investigated the dynamics of CD4 T cell memory populations in the RV217 (ECHO) cohort during the acute phase of infection.

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