Publications by authors named "Sophie Uyoga"

Background: African children with severe malaria are at increased risk of non-typhoidal salmonellae co-infection. Broad-spectrum antibiotics are recommended by guidelines but the optimal class and dose have not been established. We investigated the optimal dose of oral dispersible azithromycin and whether simple clinical criteria and point-of-care biomarkers could target antibiotics to those at greatest risk of bacterial co-infection.

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Background: The Dantu blood group variant protects against P. falciparum infections but its wider consequences have not been previously explored. Here, we investigate the impact of Dantu on susceptibility to bacteraemia.

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Background: Single low-dose primaquine (SLDPQ) effectively blocks the transmission of Plasmodium falciparum malaria, but anxiety remains regarding its haemolytic potential in patients with glucose-6-phopshate dehydrogenase (G6PD) deficiency. We, therefore, examined the independent effects of several factors on haemoglobin (Hb) dynamics in falciparum-infected children with a particular interest in SLDPQ and G6PD status.

Methods: This randomised, double-blind, placebo-controlled, safety trial was conducted in Congolese and Ugandan children aged 6 months-11 years with acute uncomplicated P.

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Background: There are no pharmacokinetic data of single low dose primaquine (SLDPQ) as transmission blocking in African children with acute Plasmodium falciparum and glucose-6-phosphate dehydrogenase deficiency (G6PDd).

Methods: Primaquine pharmacokinetics of age-dosed SLDPQ (shown previously to be gametocytocidal with similar tolerability as placebo) were characterised in falciparum-infected Ugandan and Congolese children aged 6 months to 11 years, treated on admission with standard 3-day dihydroartemisinin-piperaquine or artemether-lumefantrine plus SLDPQ: 6 m-<1 y: 1.25 mg, 1-5 y: 2.

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Background: We sought to estimate SARS-CoV-2 antibody seroprevalence within representative samples of the Kenyan population during the third year of the COVID-19 pandemic and the second year of COVID-19 vaccine use.

Methods: We conducted cross-sectional serosurveys among randomly selected, age-stratified samples of Health and Demographic Surveillance System (HDSS) residents in Kilifi and Nairobi. Anti-spike (anti-S) immunoglobulin G (IgG) serostatus was measured using a validated in-house ELISA and antibody concentrations estimated with reference to the WHO International Standard for anti-SARS-CoV-2 immunoglobulin.

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Article Synopsis
  • Blood group O provides protection against severe malaria, while non-O blood groups (such as AA, AB, BB, and AO) are associated with increased risk and larger P. falciparum-host red blood cell rosettes.
  • The study tested whether double dose non-O genotypes (AA, BB, AB) have a higher risk of severe malaria compared to single dose heterozygotes (AO, BO) among Kenyan children.
  • Results indicated that double dose genotypes had significantly higher odds ratios for severe malaria and formed larger rosettes in vitro, supporting the idea that these genotypes increase susceptibility to malaria pathology.
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African children with severe malaria are susceptible to Gram-negative bacterial co-infection, largely non-typhoidal Salmonellae, leading to a substantially higher rates of in-hospital and post-discharge mortality than those without bacteraemia. Current evidence for treating co-infection is lacking, and there is no consensus on the dosage or length of treatment required. We therefore aimed to establish the appropriate dose of oral dispersible azithromycin as an antimicrobial treatment for children with severe malaria and to investigate whether antibiotics can be targeted to those at greatest risk of bacterial co-infection using clinical criteria alone or in combination with rapid diagnostic biomarker tests.

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Background: Most of the studies that have informed the public health response to the COVID-19 pandemic in Kenya have relied on samples that are not representative of the general population. We conducted population-based serosurveys at three Health and Demographic Surveillance Systems (HDSSs) to determine the cumulative incidence of infection with SARS-CoV-2.

Methods: We selected random age-stratified population-based samples at HDSSs in Kisumu, Nairobi and Kilifi, in Kenya.

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Policymakers in Africa need robust estimates of the current and future spread of SARS-CoV-2. We used national surveillance PCR test, serological survey and mobility data to develop and fit a county-specific transmission model for Kenya up to the end of September 2020, which encompasses the first wave of SARS-CoV-2 transmission in the country. We estimate that the first wave of the SARS-CoV-2 pandemic peaked before the end of July 2020 in the major urban counties, with 30-50% of residents infected.

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Background: WHO recommends gametocytocidal, single low-dose primaquine for blocking the transmission of Plasmodium falciparum; however, safety concerns have hampered the implementation of this strategy in sub-Saharan Africa. We aimed to investigate the safety of age-dosed, single low-dose primaquine in children from Uganda and the Democratic Republic of the Congo.

Methods: We conducted this randomised, double-blind, placebo-controlled, non-inferiority trial at the Mbale Regional Referral Hospital, Mbale, Uganda, and the Kinshasa Mahidol Oxford Research Unit, Kinshasa, Democratic Republic of the Congo.

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Introduction: The high proportion of SARS-CoV-2 infections that have remained undetected presents a challenge to tracking the progress of the pandemic and estimating the extent of population immunity.

Methods: We used residual blood samples from women attending antenatal care services at three hospitals in Kenya between August 2020 and October 2021and a validated IgG ELISA for SARS-Cov-2 spike protein and adjusted the results for assay sensitivity and specificity. We fitted a two-component mixture model as an alternative to the threshold analysis to estimate of the proportion of individuals with past SARS-CoV-2 infection.

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Background And Objectives: Adequate supplies of donor blood remain a major challenge in sub-Saharan Africa. This is exacerbated by a lack of confirmatory testing for transfusion-transmitted infections by blood transfusion services (BTS), leading to significant blood disposal owing to putatively high seroprevalence rates amongst Ugandan blood donors. We aimed to ascertain the false discovery rate of the Architect anti-hepatitis C virus (HCV) screening assay and categorize screen-reactive samples into three groups: presumed false positive, active and past infection, and develop an algorithm for confirmatory testing.

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Article Synopsis
  • - The study analyzed the cost-effectiveness of COVID-19 vaccination in Kenya, considering that at least 80% of the population had prior exposure to the virus due to natural immunity.
  • - Findings indicated that a slow vaccine roll-out targeting 30% of adults, especially those over 50, could prevent 54% of expected deaths and be cost-saving, while increased coverage beyond this was less effective in terms of cost relative to health outcomes.
  • - Overall, the research suggests that, given the existing immunity in the population, prioritizing younger adults for vaccination may not be a cost-effective strategy anymore.
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Invasive bacterial disease is a major cause of morbidity and mortality in African children. Despite being caused by diverse pathogens, children with sepsis are clinically indistinguishable from one another. In spite of this, most genetic susceptibility loci for invasive infection that have been discovered to date are pathogen specific and are not therefore suggestive of a shared genetic architecture of bacterial sepsis.

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Severe malaria caused by is difficult to diagnose accurately in children in high-transmission settings. Using data from 2649 pediatric and adult patients enrolled in four studies of severe illness in three countries (Bangladesh, Kenya, and Uganda), we fitted Bayesian latent class models using two diagnostic markers: the platelet count and the plasma concentration of histidine-rich protein 2 (HRP2). In severely ill patients with clinical features consistent with severe malaria, the combination of a platelet count of ≤150,000/μl and a plasma HRP2 concentration of ≥1000 ng/ml had an estimated sensitivity of 74% and specificity of 93% in identifying severe falciparum malaria.

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Background: Sickle cell anaemia (SCA) has historically been associated with high levels of childhood mortality in Africa. Although malaria has a major contribution to this mortality, to date, the clinical pathology of malaria among children with SCA has been poorly described. We aimed to explore the relationship between SCA and Plasmodium falciparum malaria in further detail by investigating the burden and severity of malaria infections among children recruited with severe anaemia to the TRACT trial of blood transfusion in Africa.

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Objectives: Fluid bolus resuscitation in African children is harmful. Little research has evaluated physiologic effects of maintenance-only fluid strategy.

Design: We describe the efficacy of fluid-conservative resuscitation of septic shock using case-fatality, hemodynamic, and myocardial function endpoints.

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Article Synopsis
  • The TRACT trial focused on the timing and volume of blood transfusions in children with severe anaemia (hemoglobin <6 g/dL) and assessed mortality rates within 28 days as the primary outcome.
  • A secondary analysis was conducted to investigate the safety and efficacy of different blood components (whole blood vs. red cell concentrates) in children who received immediate transfusions during the trial.
  • Results showed that children who received whole blood had a significantly better hemoglobin recovery at 8 hours compared to those who received red cell concentrates, highlighting potential differences in clinical outcomes based on the type of transfusion.
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Sickle cell anemia (SCA) is common in sub-Saharan Africa where approximately 1% of births are affected. Severe anemia is a common cause for hospital admission within the region yet few studies have investigated the contribution made by SCA. The Transfusion and Treatment of severe anemia in African Children Trial (ISRCTN84086586) investigated various treatment strategies in 3983 children admitted with severe anemia (hemoglobin < 6.

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Many SARS-CoV-2 antibody detection assays have been developed but their differential performance is not well described. In this study we compared an in-house (KWTRP) ELISA which has been used extensively to estimate seroprevalence in the Kenyan population with WANTAI, an ELISA which has been approved for widespread use by the WHO. Using a wide variety of sample sets including pre-pandemic samples (negative gold standard), SARS-CoV-2 PCR positive samples (positive gold standard) and COVID-19 test samples from different periods (unknowns), we compared performance characteristics of the two assays.

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In October 2020, anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) G seroprevalence among truck drivers and their assistants (TDA) in Kenya was 42.3%, higher than among healthcare workers and blood donors. Truck drivers and their assistants transport essential supplies during the coronavirus disease 2019 pandemic, placing them at increased risk of being infected and of transmitting SARS-CoV-2 over a wide geographical area.

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Policy decisions on COVID-19 interventions should be informed by a local, regional and national understanding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. Epidemic waves may result when restrictions are lifted or poorly adhered to, variants with new phenotypic properties successfully invade, or infection spreads to susceptible subpopulations. Three COVID-19 epidemic waves have been observed in Kenya.

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Malaria and invasive non-typhoidal Salmonella (NTS) are life-threatening infections that often co-exist in African children. The iron-regulatory hormone hepcidin is highly upregulated during malaria and controls the availability of iron, a critical nutrient for bacterial growth. We investigated the relationship between Plasmodium falciparum malaria and NTS bacteremia in all pediatric admissions aged <5 years between August 1998 and October 2019 (n=75,034).

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