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Publications (36)
Background:
Yellow fever vaccine is highly effective with a single dose, but vaccine supply is limited. The minimum dose requirements for seroconversion remain unknown.
Methods:
In this double-blind, randomized, noninferiority trial in Uganda and Kenya, we assigned adults with no history of yellow fever vaccination or infection to receive vaccin...
Accurate laboratory reference ranges (RR) are essential for diagnosis and management of patients in routine clinical care and clinical trials. RRs vary between geographical location due to differences in population demographics and blood analysis equipment, so locally derived RRs are essential. Here we establish adult and paediatric RRs for a rural...
Falciparum malaria is a substantial public health problem. Vaccines and monoclonal antibodies targeting the Plasmodium falciparum (Pf) circumsporozoite protein (CSP) are promising control strategies. The protective mechanisms of anti-PfCSP antibodies are incompletely understood, and levels of anti-PfCSP antibodies are inconsistently predictive of p...
Introduction Antimalarial therapeutic efficacy studies are routinely conducted in malaria-endemic countries to assess the effectiveness of antimalarial treatment strategies. Targeted amplicon sequencing (AmpSeq) uniquely identifies and quantifies genetically distinct parasites within an infection. In this study, AmpSeq of Plasmodium falciparum apic...
Chronic hepatitis B infection (CHB) is a significant problem worldwide with around 300 million people infected. Ambitious goals have been set towards its elimination as a public health threat by 2030. However, accurate seroprevalence estimates in many countries are lacking or fail to provide representative population estimates, particularly in the...
Background
There are limited data on the immunogenicity of coronavirus disease 2019 (COVID-19) vaccines in African populations. Here we report the immunogenicity and safety of the ChAdOx1 nCoV-19 (AZD1222) vaccine from a phase 1/2 single-blind, randomised, controlled trial among adults in Kenya conducted as part of the early studies assessing vacci...
Introduction Antimalarial therapeutic efficacy studies are routinely conducted in malaria-endemic countries to assess the effectiveness of antimalarial treatment strategies. Targeted amplicon sequencing (AmpSeq) uniquely identifies and quantifies genetically distinct parasites within an infection. In this study, AmpSeq of Plasmodium falciparum apic...
Background: There are limited data on the immunogenicity of coronavirus disease 2019 (COVID-19) vaccines in African populations. Here we report the immunogenicity and safety of the ChAdOx1 nCoV-19 (AZD1222) vaccine from a phase 1/2 single-blind, randomised, controlled trial among adults in Kenya conducted as part of the early studies assessing vacc...
Coronavirus Disease-2019 tests require a Nasopharyngeal (NP) and/or Oropharyngeal (OP) specimen from the upper airway, from which virus RNA is extracted and detected through quantitative reverse transcription-Polymerase Chain Reaction (qRT-PCR). The viability of the virus is maintained after collection by storing the NP/OP swabs in Viral Transport...
There is a growing concern for malaria control in the Horn of Africa region due to the spread and rise in the frequency of Plasmodium falciparum Histidine-rich Protein (hrp) 2 and 3 deletions. Parasites containing these gene deletions escape detection by the major PfHRP2-based rapid diagnostic test. In this study, the presence of Pfhrp2/3 deletions...
Introduction: Antimalarial therapeutic efficacy studies are routinely conducted in malaria-endemic countries to assess the effectiveness of antimalarial treatment strategies. Targeted amplicon sequencing (AmpSeq) uniquely identifies and quantifies genetically distinct parasites within an infection. In this study, AmpSeq of Plasmodium falciparum api...
Background
In sub-Saharan Africa, data on virologic outcomes of young people living with HIV (YLWH) enrolled on antiretroviral therapy (ART) remains scarce. In this study, we describe the prevalence of HIV virological non-suppression (VNS) and its associated factors among YLWH aged 18–24 years from the Kenyan coast.
Methods
Data were analyzed for...
Laboratory diagnosis plays a critical role in the containment of a pandemic. Strong laboratory quality management systems (QMS) are essential for laboratory diagnostic services. However, low laboratory capacities in resource-limited countries has made the maintenance of laboratory quality assurance, especially during a pandemic, a daunting task. In...
Antimalarial therapeutic efficacy studies are routinely conducted in malaria-endemic countries to assess the effectiveness of antimalarial treatment strategies. Targeted amplicon deep sequencing (TADS) uniquely identifies and quantifies genetically distinct parasites within an infection. In this study, TADS Plasmodium falciparum apical membrane ant...
Laboratory diagnosis plays a critical role in the containment of a pandemic. Strong laboratory quality management systems (QMS) are essential for laboratory diagnostic services. However, low laboratory capacities in resource-limited countries has made the maintenance of laboratory quality assurance, especially during a pandemic, a daunting task. In...
Severe falciparum malaria has substantially affected human evolution. Genetic association studies of patients with clinically defined severe malaria and matched population controls have helped characterise human genetic susceptibility to severe malaria, but phenotypic imprecision compromises discovered associations. In areas of high malaria transmi...
Background
Triple antimalarial combination therapies combine potent and rapidly cleared artemisinins or related synthetic ozonides, such as arterolane, with two, more slowly eliminated partner drugs to reduce the risk of resistance. We aimed to assess the safety, tolerability, and efficacy of arterolane–piperaquine–mefloquine versus arterolane–pipe...
Severe falciparum malaria has substantially affected human evolution. Genetic association studies of patients with clinically defined severe malaria and matched population controls have helped characterise human genetic susceptibility to severe malaria, but phenotypic imprecision compromises discovered associations. In areas of high malaria transmi...
Background:
Many parts of Africa have witnessed reductions in Plasmodium falciparum transmission over the last 15 years. Since immunity to malaria is acquired more rapidly at higher transmission, the slower acquisition of immunity at lower transmission may partially offset the benefits of reductions in transmission. We examined the clinical spectr...
Background:
Africa has the highest incidence of gonorrhoea in the world. However, little is known about gonococcal populations in this continent or mechanisms of antimicrobial resistance (AMR).
Methods:
Whole genome sequence data were analysed from 103 N. gonorrhoeae isolates from 73 patients, mainly men who have sex with men from coastal Kenya....
No data exist on Hepatitis B virus (HBV) incidence among African men who have sex with men (MSM). We tested plasma samples archived between 2005 and 2014 for HBV core seroconversion in a cohort of 312 initially HIV-1-negative MSM with no evidence of prior HBV-infection. HBV incidence was 3.5/100 person-years [PY] (95% confidence interval [CI], 2.0-...
Herpes simplex virus type 2 (HSV-2) is an important cause of genital ulcers and can increase the risk for human immunodeficiency virus type 1 (HIV-1) transmission. Our objective was to determine the incidence and correlates of HSV-2 infection in HIV-1-seronegative Kenyan men reporting high-risk sexual behavior, compared with high-risk HIV-1-seroneg...
Herpes Simplex Virus type 2 (HSV-2) has public health importance as a leading cause of genital ulcers, a co-factor in HIV-1 acquisition and transmission and as a cause of neonatal herpes infections. Little is known of its epidemiology and burden in Coastal Kenya.
We screened plasma samples for HSV-2 infection from 826 women aged 15-34 years who par...
Estimates of the burden of invasive bacterial disease in sub-Saharan Africa have previously relied on selected groups of patients, such as inpatients; they are, therefore, probably underestimated, potentially hampering vaccine implementation. Our aim was to assess the incidence of bacteraemia in all children presenting to a hospital in Kenya, irres...
Etest susceptibilities to amoxicillin, chloramphenicol, and trimethoprim-sulfamethoxazole of 240 invasive isolates of Haemophilus influenzae cultured from children in rural Kenya were 66%, 66%, and 38%, respectively. Resistance increased markedly over 9 years and
was concentrated among serotype b isolates. In Africa, the increasing cost of treating...
To determine the pattern of resistance among Gram-negative bacilli causing invasive bacterial disease for the antibiotics that are already in common use in Kilifi, Kenya and for two potential alternatives, ciprofloxacin and cefotaxime. Also, to determine whether prevalence and severity of resistance was increasing over time, to identify patients wh...
To determine how well antibiotic treatment is targeted by simple clinical syndromes and to what extent drug resistance threatens affordable antibiotics.
Observational study involving a priori definition of a hierarchy of syndromic indications for antibiotic therapy derived from World Health Organization integrated management of childhood illness an...
There are few epidemiologic data on invasive bacterial infections among children in sub-Saharan Africa. We studied every acute pediatric admission to a rural district hospital in Kenya to examine the prevalence, incidence, types, and outcome of community-acquired bacteremia.
Between August 1998 and July 2002, we cultured blood on admission from 19,...
To determine the association between Plasmodium falciparum malaria and non-typhi Salmonella in children.
Cross-sectional hospital based study.
Kilifi District Hospital (KDH) between January 1997 and June 2001.
Children aged between three months to 123 months (mean age 28.28 months) and who had been admitted to the paediatric or High Dependency Rese...
The diagnosis of acute bacterial meningitis in children is difficult in sub-Saharan Africa, because the clinical features overlap with those of other common diseases, and laboratory facilities are inadequate in many areas. We have assessed the value of non-laboratory tests and incomplete laboratory data in diagnosing childhood acute bacterial menin...
