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"OCHIENG, Benjamin"
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Animal-related factors associated with moderate-to-severe diarrhea in children younger than five years in western Kenya: A matched case-control study
2017
Diarrheal disease remains among the leading causes of global mortality in children younger than 5 years. Exposure to domestic animals may be a risk factor for diarrheal disease. The objectives of this study were to identify animal-related exposures associated with cases of moderate-to-severe diarrhea (MSD) in children in rural western Kenya, and to identify the major zoonotic enteric pathogens present in domestic animals residing in the homesteads of case and control children.
We characterized animal-related exposures in a subset of case and control children (n = 73 pairs matched on age, sex and location) with reported animal presence at home enrolled in the Global Enteric Multicenter Study in western Kenya, and analysed these for an association with MSD. We identified potentially zoonotic enteric pathogens in pooled fecal specimens collected from domestic animals resident at children's homesteads. Variables that were associated with decreased risk of MSD were washing hands after animal contact (matched odds ratio [MOR] = 0.2; 95% CI 0.08-0.7), and presence of adult sheep that were not confined in a pen overnight (MOR = 0.1; 0.02-0.5). Variables that were associated with increased risk of MSD were increasing number of sheep owned (MOR = 1.2; 1.0-1.5), frequent observation of fresh rodent excreta (feces/urine) outside the house (MOR = 7.5; 1.5-37.2), and participation of the child in providing water to chickens (MOR = 3.8; 1.2-12.2). Of 691 pooled specimens collected from 2,174 domestic animals, 159 pools (23%) tested positive for one or more potentially zoonotic enteric pathogens (Campylobacter jejuni, C. coli, non-typhoidal Salmonella, diarrheagenic E. coli, Giardia, Cryptosporidium, or rotavirus). We did not find any association between the presence of particular pathogens in household animals, and MSD in children.
Public health agencies should continue to promote frequent hand washing, including after animal contact, to reduce the risk of MSD. Future studies should address specific causal relations of MSD with sheep and chicken husbandry practices, and with the presence of rodents.
Journal Article
Indirect Effects of 10-Valent Pneumococcal Conjugate Vaccine Against Adult Pneumococcal Pneumonia in Rural Western Kenya
by
Auko, Joshua
,
Bigogo, Godfrey M.
,
Odoyo, Arthur
in
Adult
,
ARTICLES AND COMMENTARIES
,
Coinfection
2019
Abstract
Background
Data on pneumococcal conjugate vaccine (PCV) indirect effects in low-income countries with high human immunodeficiency virus (HIV) burden are limited. We examined adult pneumococcal pneumonia incidence before and after PCV introduction in Kenya in 2011.
Methods
From 1 January 2008 to 31 December 2016, we conducted surveillance for acute respiratory infection (ARI) among ~12 000 adults (≥18 years) in western Kenya, where HIV prevalence is ~17%. ARI cases (cough or difficulty breathing or chest pain, plus temperature ≥38.0°C or oxygen saturation <90%) presenting to a clinic underwent blood culture and pneumococcal urine antigen testing (UAT). We calculated ARI incidence and adjusted for healthcare seeking. The proportion of ARI cases with pneumococcus detected among those with complete testing (blood culture and UAT) was multiplied by adjusted ARI incidence to estimate pneumococcal pneumonia incidence.
Results
Pre-PCV (2008–2010) crude and adjusted ARI incidences were 3.14 and 5.30/100 person-years-observation (pyo), respectively. Among ARI cases, 39.0% (340/872) had both blood culture and UAT; 21.2% (72/340) had pneumococcus detected, yielding a baseline pneumococcal pneumonia incidence of 1.12/100 pyo (95% confidence interval [CI]: 1.0–1.3). In each post-PCV year (2012–2016), the incidence was significantly lower than baseline; with incidence rate ratios (IRRs) of 0.53 (95% CI: 0.31–0.61) in 2012 and 0.13 (95% CI: 0.09–0.17) in 2016. Similar declines were observed in HIV-infected (IRR: 0.13; 95% CI: 0.08–0.22) and HIV-uninfected (IRR: 0.10; 95% CI: 0.05–0.20) adults.
Conclusions
Adult pneumococcal pneumonia declined in western Kenya following PCV introduction, likely reflecting vaccine indirect effects. Evidence of herd protection is critical for guiding PCV policy decisions in resource-constrained areas.
Data on pneumococcal conjugate vaccine (PCV) indirect effects on adult pneumococcal pneumonia in Africa are limited. In rural western Kenya, following PCV introduction, the incidence of adult pneumococcal decreased by 47–94%.
Journal Article
Characterization of Shigella flexneri serotype 6 strains from geographically diverse low- and middle-income countries
by
Ogwel, Billy
,
Kotloff, Karen L.
,
Lemme-Dumit, Jose M.
in
Anti-Bacterial Agents - pharmacology
,
Biological invasions
,
Chromosomes
2025
Shigellosis is an ongoing global public health crisis with >270 million annual episodes among all age groups; however, the greatest disease burden is among children in low- and middle-income countries (LMIC). The lack of a licensed Shigella vaccine and the observed rise in antimicrobial-resistant Shigella spp. highlights the urgency for effective preventative and interventional strategies. The inclusion of S. flexneri serotype 6 ( Sf 6) is a necessary component of a multivalent vaccine strategies based on its clinical and epidemiological importance. Given the genomic diversity of Sf 6 compared with other S. flexneri serotypes and Sf 6 unique O-antigen core structure, serotype-specific characterization of Sf 6 is a critical step to inform Shigella -directed vaccine and alternative therapeutic designs. Herein, we identified conserved genomic content among a large collection of temporally and geographically diverse Sf 6 clinical isolates and characterized genotypic and phenotypic properties that separate Sf 6 from non- Sf 6 S. flexneri serotypes.
Journal Article
Differing Burden and Epidemiology of Non-Typhi Salmonella Bacteremia in Rural and Urban Kenya, 2006–2009
by
Cosmas, Leonard
,
Olack, Beatrice
,
Tabu, Collins
in
Acquired immune deficiency syndrome
,
Adult
,
Adults
2012
The epidemiology of non-Typhi Salmonella (NTS) bacteremia in Africa will likely evolve as potential co-factors, such as HIV, malaria, and urbanization, also change.
As part of population-based surveillance among 55,000 persons in malaria-endemic, rural and malaria-nonendemic, urban Kenya from 2006-2009, blood cultures were obtained from patients presenting to referral clinics with fever ≥38.0°C or severe acute respiratory infection. Incidence rates were adjusted based on persons with compatible illnesses, but whose blood was not cultured.
NTS accounted for 60/155 (39%) of blood culture isolates in the rural and 7/230 (3%) in the urban sites. The adjusted incidence in the rural site was 568/100,000 person-years, and the urban site was 51/100,000 person-years. In both sites, the incidence was highest in children <5 years old. The NTS-to-typhoid bacteremia ratio in the rural site was 4.6 and in the urban site was 0.05. S. Typhimurium represented >85% of blood NTS isolates in both sites, but only 21% (urban) and 64% (rural) of stool NTS isolates. Overall, 76% of S. Typhimurium blood isolates were multi-drug resistant, most of which had an identical profile in Pulse Field Gel Electrophoresis. In the rural site, the incidence of NTS bacteremia increased during the study period, concomitant with rising malaria prevalence (monthly correlation of malaria positive blood smears and NTS bacteremia cases, Spearman's correlation, p = 0.018 for children, p = 0.16 adults). In the rural site, 80% of adults with NTS bacteremia were HIV-infected. Six of 7 deaths within 90 days of NTS bacteremia had HIV/AIDS as the primary cause of death assigned on verbal autopsy.
NTS caused the majority of bacteremias in rural Kenya, but typhoid predominated in urban Kenya, which most likely reflects differences in malaria endemicity. Control measures for malaria, as well as HIV, will likely decrease the burden of NTS bacteremia in Africa.
Journal Article
Risk Factors for Death among Children Less than 5 Years Old Hospitalized with Diarrhea in Rural Western Kenya, 2005–2007: A Cohort Study
2012
Diarrhea is a leading cause of childhood morbidity and mortality in sub-Saharan Africa. Data on risk factors for mortality are limited. We conducted hospital-based surveillance to characterize the etiology of diarrhea and identify risk factors for death among children hospitalized with diarrhea in rural western Kenya.
We enrolled all children <5 years old, hospitalized with diarrhea (≥3 loose stools in 24 hours) at two district hospitals in Nyanza Province, western Kenya. Clinical and demographic information was collected. Stool specimens were tested for bacterial and viral pathogens. Bivariate and multivariable logistic regression analyses were carried out to identify risk factors for death. From May 23, 2005 to May 22, 2007, 1,146 children <5 years old were enrolled; 107 (9%) children died during hospitalization. Nontyphoidal Salmonella were identified in 10% (118), Campylobacter in 5% (57), and Shigella in 4% (42) of 1,137 stool samples; rotavirus was detected in 19% (196) of 1,021 stool samples. Among stools from children who died, nontyphoidal Salmonella were detected in 22%, Shigella in 11%, rotavirus in 9%, Campylobacter in 5%, and S. Typhi in <1%. In multivariable analysis, infants who died were more likely to have nontyphoidal Salmonella (adjusted odds ratio [aOR] = 6·8; 95% CI 3·1-14·9), and children <5 years to have Shigella (aOR = 5·5; 95% CI 2·2-14·0) identified than children who survived. Children who died were less likely to be infected with rotavirus (OR = 0·4; 95% CI 0·2-0·8). Further risk factors for death included being malnourished (aOR = 4·2; 95% CI 2·1-8·7); having oral thrush on physical exam (aOR = 2·3; 95% CI 1·4-3·8); having previously sought care at a hospital for the illness (aOR = 2·2; 95% CI 1·2-3·8); and being dehydrated as diagnosed at discharge/death (aOR = 2·5; 95% CI 1·5-4·1). A clinical diagnosis of malaria, and malaria parasites seen on blood smear, were not associated with increased risk of death. This study only captured in-hospital childhood deaths, and likely missed a substantial number of additional deaths that occurred at home.
Nontyphoidal Salmonella and Shigella are associated with mortality among rural Kenyan children with diarrhea who access a hospital. Improved prevention and treatment of diarrheal disease is necessary. Enhanced surveillance and simplified laboratory diagnostics in Africa may assist clinicians in appropriately treating potentially fatal diarrheal illness.
Journal Article
Multi-drug resistant non-typhoidal Salmonella associated with invasive disease in western Kenya
2018
Non-typhoidal Salmonella (NTS) is a leading cause of bloodstream infections in Africa, but the various contributions of host susceptibility versus unique pathogen virulence factors are unclear. We used data from a population-based surveillance platform (population ~25,000) between 2007-2014 and NTS genome-sequencing to compare host and pathogen-specific factors between individuals presenting with NTS bacteremia and those presenting with NTS diarrhea. Salmonella Typhimurium ST313 and Salmonella Enteritidis ST11 were the most common isolates. Multi-drug resistant strains of NTS were more commonly isolated from patients presenting with NTS bacteremia compared to NTS diarrhea. This relationship was observed in patients under age five [aOR = 15.16, 95% CI (2.84-81.05), P = 0.001], in patients five years and older, [aOR = 6.70 95% CI (2.25-19.89), P = 0.001], in HIV-uninfected patients, [aOR = 21.61, 95% CI (2.53-185.0), P = 0.005], and in patients infected with Salmonella serogroup B [aOR = 5.96, 95% CI (2.28-15.56), P < 0.001] and serogroup D [aOR = 14.15, 95% CI (1.10-182.7), P = 0.042]. Thus, multi-drug-resistant NTS was strongly associated with bacteremia compared to diarrhea among children and adults. This association was seen in HIV-uninfected individuals infected with either S. Typhimurium or S. Enteritidis. Risk of developing bacteremia from NTS infection may be driven by virulence properties of the Salmonella pathogen.
Journal Article
Clinical, environmental, and behavioral characteristics associated with Cryptosporidium infection among children with moderate-to-severe diarrhea in rural western Kenya, 2008–2012: The Global Enteric Multicenter Study (GEMS)
by
Oundo, Joseph
,
Laserson, Kayla
,
Levine, Myron M.
in
Analysis
,
Biology and Life Sciences
,
Causes of
2018
Cryptosporidium is a leading cause of moderate-to-severe diarrhea (MSD) in young children in Africa. We examined factors associated with Cryptosporidium infection in MSD cases enrolled at the rural western Kenya Global Enteric Multicenter Study (GEMS) site from 2008-2012.
At health facility enrollment, stool samples were tested for enteric pathogens and data on clinical, environmental, and behavioral characteristics collected. Each child's health status was recorded at 60-day follow-up. Data were analyzed using logistic regression. Of the 1,778 children with MSD enrolled as cases in the GEMS-Kenya case-control study, 11% had Cryptosporidium detected in stool by enzyme immunoassay; in a genotyped subset, 81% were C. hominis. Among MSD cases, being an infant, having mucus in stool, and having prolonged/persistent duration diarrhea were associated with being Cryptosporidium-positive. Both boiling drinking water and using rainwater as the main drinking water source were protective factors for being Cryptosporidium-positive. At follow-up, Cryptosporidium-positive cases had increased odds of being stunted (adjusted odds ratio [aOR] = 1.65, 95% CI: 1.06-2.57), underweight (aOR = 2.08, 95% CI: 1.34-3.22), or wasted (aOR = 2.04, 95% CI: 1.21-3.43), and had significantly larger negative changes in height- and weight-for-age z-scores from enrollment.
Cryptosporidium contributes significantly to diarrheal illness in young children in western Kenya. Advances in point of care detection, prevention/control approaches, effective water treatment technologies, and clinical management options for children with cryptosporidiosis are needed.
Journal Article
Rotavirus Disease Burden and Impact and Cost-Effectiveness of a Rotavirus Vaccination Program in Kenya
2009
BackgroundThe projected impact and cost-effectiveness of rotavirus vaccination are important for supporting rotavirus vaccine introduction in Africa, where limited health intervention funds are available MethodsHospital records, health utilization surveys, verbal autopsy data, and surveillance data on diarrheal disease were used to determine rotavirus-specific rates of hospitalization, clinic visits, and deaths due to diarrhea among children <5 years of age in Nyanza Province, Kenya. Rates were extrapolated nationally with use of province-specific data on diarrheal illness. Direct medical costs were estimated using record review and World Health Organization estimates. Household costs were collected through parental interviews. The impact of vaccination on health burden and on the cost-effectiveness per disability-adjusted life-year and lives saved were calculated ResultsAnnually in Kenya, rotavirus infection causes 19% of hospitalizations and 16% of clinic visits for diarrhea among children <5 years of age and causes 4471 deaths, 8781 hospitalizations, and 1,443,883 clinic visits. Nationally, rotavirus disease costs the health care system $10.8 million annually. Routine vaccination with a 2-dose rotavirus vaccination series would avert 2467 deaths (55%), 5724 hospitalizations (65%), and 852,589 clinic visits (59%) and would save 58 disability-adjusted life-years per 1000 children annually. At $3 per series, a program would cost $2.1 million in medical costs annually; the break-even price is $2.07 per series ConclusionsA rotavirus vaccination program would reduce the substantial burden of rotavirus disease and the economic burden in Kenya
Journal Article
Prolonged Hospitalization Among Children Aged < 5 Years Admitted With Acute Gastroenteritis at Siaya County Referral Hospital, in Rural Western Kenya: 2010–2020
2025
Background Acute gastroenteritis (AGE) causes substantial morbidity and mortality in children < 5 years old accounting for 9 million hospitalizations. Prolonged hospitalization can cause dire consequences to the patient and healthcare system. However, data on factors associated with prolonged hospitalization for AGE in developing countries are limited. Objectives We aim to describe trends and assess factors associated with prolonged hospitalization among children < 5 years admitted with AGE in western Kenya. Methods Children with AGE ( ≥ 3 loose stools and/or ≥ 1 episode of unexplained vomiting with loose stool within 24 h) hospitalized at Siaya County Referral Hospital from January 2010 through December 2020 were included. Prolonged hospitalization was defined as admission for ≥ 5 days. Trends of prolonged AGE hospitalizations were assessed using Cochran–Armitage trend test, while factors associated with prolonged hospitalization for AGE were determined by unconditional logistic regression. Results Of the 12,546 all‐cause admissions among children < 5 years, 2271 (18.1%) children had AGE; 681 (32.8%) had prolonged hospitalization. There was a significant difference in the prevalence of prolonged hospitalization over time, with a peak in 2010 (42.8%) and a low in 2016 (10.8%). Older children (12–23 months: (adjusted odds ratio [aOR]: 0.69; 95% confidence interval [95% CI]: 0.49–0.97)) and those who vomited everything (aOR: 0.69; 95% CI: 0.52–0.90) were less likely to have prolonged hospitalization. Children who had a bulging fontanel (aOR: 3.21; 95% CI: 1.12–9.20) or chest in drawing (aOR: 1.49; 95% CI: 1.02–2.18) or were severely stunted (aOR: 2.67; 95% CI: 1.89–3.79) or severely wasted (aOR: 2.34; 95% CI: 1.65–3.30) were more likely to have prolonged hospitalization. Conclusion Children with severe diarrheal illness with malnutrition are at high risk of prolonged hospitalization. Targeted interventions such as increased clinical and diagnostics monitoring for at‐risk children with AGE may need to be prioritized to reduce possible prolonged hospitalization.
Journal Article
Bacterial Factors Associated with Lethal Outcome of Enteropathogenic Escherichia coli Infection: Genomic Case-Control Studies
by
Levine, Myron M.
,
Donnenberg, Michael S.
,
Panchalingam, Sandra
in
Antigens
,
Bacteria
,
Case-Control Studies
2015
Typical enteropathogenic Escherichia coli (tEPEC) strains were associated with mortality in the Global Enteric Multicenter Study (GEMS). Genetic differences in tEPEC strains could underlie some of the variability in clinical outcome.
We produced draft genome sequences of all available tEPEC strains from GEMS lethal infections (LIs) and of closely matched EPEC strains from GEMS subjects with non-lethal symptomatic infections (NSIs) and asymptomatic infections (AIs) to identify gene clusters (potential protein encoding sequences sharing ≥90% nucleotide sequence identity) associated with lethality.
Among 14,412 gene clusters identified, the presence or absence of 392 was associated with clinical outcome. As expected, more gene clusters were associated with LI versus AI than LI versus NSI. The gene clusters more prevalent in strains from LI than those from NSI and AI included those encoding proteins involved in O-antigen biogenesis, while clusters encoding type 3 secretion effectors EspJ and OspB were among those more prevalent in strains from non-lethal infections. One gene cluster encoding a variant of an NleG ubiquitin ligase was associated with LI versus AI, while two other nleG clusters had the opposite association. Similar associations were found for two nleG gene clusters in an additional, larger sample of NSI and AI GEMS strains.
Particular genes are associated with lethal tEPEC infections. Further study of these factors holds potential to unravel the mechanisms underlying severe disease and to prevent adverse outcomes.
Journal Article