BackgroundEnteric fever is a serious public health concern. The causative agents,Salmonella enter... more BackgroundEnteric fever is a serious public health concern. The causative agents,Salmonella entericaserovars Typhi and Paratyphi A, are frequently antimicrobial resistant (AMR), leading to limited treatment options and poorer clinical outcomes. We investigated the genomic epidemiology, resistance mechanisms and transmission dynamics of these pathogens at three urban sites in Africa and Asia.MethodsBacteria isolated from febrile children and adults at study sites in Dhaka, Kathmandu, and Blantyre were sequenced and AMR determinants identified. Phylogenomic analyses incorporating globally-representative genome data, and ancestral state reconstruction, were used to differentiate locally-circulating from imported pathogen variants.FindingsS. Paratyphi A was present in Dhaka and Kathmandu but not Blantyre.S. Typhi genotype 4.3.1 (H58) was common in all sites, but with different dominant variants (4.3.1.1.EA1 in Blantyre; 4.3.1.1 in Dhaka; 4.3.1.2 in Kathmandu). Resistance to first-line a...
RNAseq data can be used to infer genetic variants, yet its use for estimating genetic population ... more RNAseq data can be used to infer genetic variants, yet its use for estimating genetic population structure remains underexplored. Here, we construct a freely available computational tool (RGStraP) to estimate RNAseq-based genetic principal components (RG-PCs) and assess whether RG-PCs can be used to control for population structure in gene expression analyses. Using whole blood samples from understudied Nepalese populations, we show that RG-PCs had comparable results to paired array-based genotypes, with high genotype concordance and high correlations of genetic principal components, capturing subpopulations within the dataset. In differential gene expression analysis, we found that inclusion of RG-PCs as covariates reduced test statistic inflation. Our paper demonstrates that genetic population structure can be directly inferred and controlled for using RNAseq data, thus facilitating improved retrospective and future analyses of transcriptomic data.
Typhoid is a public health problem in Nepal. To generate evidence on the impact of Typhoid Conjug... more Typhoid is a public health problem in Nepal. To generate evidence on the impact of Typhoid Conjugate Vaccine (TCV), a phase 3, double-blind, randomized controlled trial was conducted in Lalitpur, Nepal. 20,000 children aged between 9 months and ≤16 years were vaccinated with a new TCV, or control vaccine. Participants were actively followed for safety and efficacy over 2 years through passive surveillance (PS) clinics. Several challenges were encountered during vaccination and PS stemming from misinformation, misconception, and fear around clinical trials in the community. Public engagement (PE) activities were conducted across various tiers moving from decision makers in the first tier; to elected local representatives in the second tier; ending with interaction in community with parents/guardians of the targeted population. Prior and during vaccination, engagement was conducted to inform about the study and discuss the importance of vaccination. Post-vaccination, engagement was conducted to inform about PS clinics, alleviate study concerns and share study updates. Direct and continuous interaction with community stakeholders, including parents/guardians of the targeted population contributed to build trust around the study and community willingness to be involved. It helped to raise awareness, drive away misconceptions, and allowed adaptation according to feedback from community members.
Introduction: Type 1 Diabetes Mellitus (DM1) has reportedly a high proportion of initial presenta... more Introduction: Type 1 Diabetes Mellitus (DM1) has reportedly a high proportion of initial presentation as diabetic ketoacidosis, more in resource-poor settings. This study was designed to assess the demographics and clinical characteristics of DM1 patients as well as their perception of diabetes management in local scenario. Method: This is a cross-sectional study of data collected prospectively by a questionnaire survey among young patients with DM1 presenting to Medical and Paediatric Referral Clinics of Patan Hospital, Nepal during April 2016 to June 2016. Ethical approval was obtained. Demographics, and disease process- initial presentation of diabetic ketoacidosis, HBA1c target, and common problems were analyzed by SPSS using chi-square and Fisher exact tests, p<0.05 considered statistically significant. Result: Fifty-eight patients were enrolled in the study. Diabetic ketoacidosis was the initial presentation in 27(46.55%). A 15(27.78%) of surveyed patients had achieved age...
Typhoid Vi-conjugate vaccines (Vi-TCV) have been developed to control typhoid fever in children i... more Typhoid Vi-conjugate vaccines (Vi-TCV) have been developed to control typhoid fever in children in endemic regions. Previously, in a human challenge model of typhoid, Vi-TCV was administered prior to deliberate ingestion of Salmonella Typhi by healthy adult volunteers in the UK. Vi-specific antibody-dependent neutrophil phagocytosis (ADNP) was associated with protection against enteric fever in this model, but it is not known if ADNP is induced by vaccination of children. We measured ADNP in a cohort of Nepalese children receiving a Vi-TCV in a field study to investigate whether functional antibody responses were also present in children in an endemic setting. Furthermore, we investigated relationships between the functional antibody measures and other properties of the antibody response, including Vi-IgG and IgA titres, and Fc region glycosylation. Antibody-dependent neutrophil phagocytosis significantly increased in children aged 9 months to 15 years between the day of vaccination...
Clinical trials of typhoid conjugate vaccine (TCV) are ongoing in 4 countries. Early data confirm... more Clinical trials of typhoid conjugate vaccine (TCV) are ongoing in 4 countries. Early data confirm safety, tolerability, and immunogenicity of typhoid conjugate vaccine, and early efficacy results are promising. These data support World Health Organization recommendations and planned country introductions. Forthcoming trial data will continue to inform programmatic use of typhoid conjugate vaccine.
Low- and middle-income countries face a high burden of typhoid and paratyphoid fever due to poor ... more Low- and middle-income countries face a high burden of typhoid and paratyphoid fever due to poor water quality and inadequate sanitation. The World Health Organization (WHO) recommends the use of typhoid conjugate vaccines (TCV) in endemic settings and Gavi, the Vaccine Alliance, supports TCV introduction. There are currently 2 WHO-prequalified TCVs with Typbar TCV introduced in Pakistan, Liberia, and Zimbabwe. Countries should assess disease burden and consider introduction of TCV for programmatic use. Several paratyphoid vaccine candidates are in early stages of development. An effective bivalent vaccine would be the most efficient way to control typhoid and paratyphoid fever.
Background: Electronic data capture systems (EDCs) have the potential to achieve efficiency and q... more Background: Electronic data capture systems (EDCs) have the potential to achieve efficiency and quality in collection of multisite data. We quantify volume, time, accuracy and costs of an EDC using large-scale census data from the STRATAA consortium, a comprehensive programme assessing population dynamics and epidemiology of typhoid fever in Malawi, Nepal and Bangladesh to inform vaccine and public health interventions. Results: A census form was developed through a structured iterative process and implemented using Open Data Kit Collect running on Android-based tablets. Data were uploaded to Open Data Kit Aggregate, then auto-synced to MySQL-defined database nightly. Data were backed-up daily from 3 sites centrally, and auto-reported weekly. Pre-census materials costs were estimated. Demographics of 308,348 individuals from 80,851 households were recorded within average of 14.7 weeks range (13-16) using 65 fieldworkers. Overall, 21.7 errors (95% confidence interval: 21.4, 22.0) per...
There is a high risk of occupational exposure to tuberculosis among healthcare workers in endemic... more There is a high risk of occupational exposure to tuberculosis among healthcare workers in endemic countries. Regular screening for tuberculosis among healthcare workers is not carried out in Nepal. Infection control measures are also not routinely implemented. The aim of this study was to determine the prevalence of active tuberculosis among staff/students at Patan Hospital. Participants were given a self-administered questionnaire and invited to undergo chest radiography. Cases were scored and reviewed based on predetermined criteria, and presumptive tuberculosis cases were invited to undergo sputum smear and culture. Participants were categorized according to the extent of patient contact and asked about history of tuberculosis medication. Among 560 participants, 76.8% had direct contact with patients. Fifty-eight (10.4%) gave history of cough >2 weeks. Based on symptom history and chest radiography, 20.0% (n=112) cases were reviewed, and 12.5% (n=14) of those reviewed had sput...
New diagnostic tests for enteric fever are urgently needed to assist with timely antimicrobial tr... more New diagnostic tests for enteric fever are urgently needed to assist with timely antimicrobial treatment of patients and to measure the efficacy of prevention measures such as vaccination. In a novel translational approach, here we use two recently developed controlled human infection models (CHIM) of enteric fever to evaluate an antibody-in-lymphocyte supernatant (ALS) assay, which can detect recent IgA antibody production by circulating B cells in ex vivo mononuclear cell culture. We calculated the discriminative ability of the ALS assay to distinguish diagnosed cases in the two CHIM studies in Oxford, prior to evaluating blood culture-confirmed diagnoses of patients presenting with fever to hospital in an endemic areas of Kathmandu, Nepal. Antibody responses to membrane preparations and lipopolysaccharide provided good sensitivity (>90%) for diagnosing systemic infection after oral challenge with Salmonella Typhi or S. Paratyphi A. Assay specificity was moderate (~60%) due to ...
Invasive infections caused by Salmonella enterica serovar Typhi and Paratyphi A are estimated to ... more Invasive infections caused by Salmonella enterica serovar Typhi and Paratyphi A are estimated to account for 12-27 million febrile illness episodes worldwide annually. Determining the true burden of typhoidal Salmonellae infections is hindered by lack of population-based studies and adequate laboratory diagnostics.The Strategic Typhoid alliance across Africa and Asia study takes a systematic approach to measuring the age-stratified burden of clinical and subclinical disease caused by typhoidal Salmonellae infections at three high-incidence urban sites in Africa and Asia. We aim to explore the natural history of Salmonella transmission in endemic settings, addressing key uncertainties relating to the epidemiology of enteric fever identified through mathematical models, and enabling optimisation of vaccine strategies. Using census-defined denominator populations of ≥100 000 individuals at sites in Malawi, Bangladesh and Nepal, the primary outcome is to characterise the burden of enter...
A 51-year-old man presented with intermittent fever, mild cough and loss of appetite of 1-month d... more A 51-year-old man presented with intermittent fever, mild cough and loss of appetite of 1-month duration. His sputum smear was positive for acid-fast bacilli and his chest radiograph revealed apical infiltrations. The patient was treated with antitubercular therapy (ATT), recovered and was well for 1 month, after which he suddenly developed focal seizures. MRI of the brain with gadolinium enhancement showed high intensity nodular foci in the frontal, parietal and occipital regions. The patient was diagnosed as a case of paradoxical reaction to ATT, and was successfully managed with continued ATT and adjunctive steroid therapy.
BackgroundEnteric fever is a serious public health concern. The causative agents,Salmonella enter... more BackgroundEnteric fever is a serious public health concern. The causative agents,Salmonella entericaserovars Typhi and Paratyphi A, are frequently antimicrobial resistant (AMR), leading to limited treatment options and poorer clinical outcomes. We investigated the genomic epidemiology, resistance mechanisms and transmission dynamics of these pathogens at three urban sites in Africa and Asia.MethodsBacteria isolated from febrile children and adults at study sites in Dhaka, Kathmandu, and Blantyre were sequenced and AMR determinants identified. Phylogenomic analyses incorporating globally-representative genome data, and ancestral state reconstruction, were used to differentiate locally-circulating from imported pathogen variants.FindingsS. Paratyphi A was present in Dhaka and Kathmandu but not Blantyre.S. Typhi genotype 4.3.1 (H58) was common in all sites, but with different dominant variants (4.3.1.1.EA1 in Blantyre; 4.3.1.1 in Dhaka; 4.3.1.2 in Kathmandu). Resistance to first-line a...
RNAseq data can be used to infer genetic variants, yet its use for estimating genetic population ... more RNAseq data can be used to infer genetic variants, yet its use for estimating genetic population structure remains underexplored. Here, we construct a freely available computational tool (RGStraP) to estimate RNAseq-based genetic principal components (RG-PCs) and assess whether RG-PCs can be used to control for population structure in gene expression analyses. Using whole blood samples from understudied Nepalese populations, we show that RG-PCs had comparable results to paired array-based genotypes, with high genotype concordance and high correlations of genetic principal components, capturing subpopulations within the dataset. In differential gene expression analysis, we found that inclusion of RG-PCs as covariates reduced test statistic inflation. Our paper demonstrates that genetic population structure can be directly inferred and controlled for using RNAseq data, thus facilitating improved retrospective and future analyses of transcriptomic data.
Typhoid is a public health problem in Nepal. To generate evidence on the impact of Typhoid Conjug... more Typhoid is a public health problem in Nepal. To generate evidence on the impact of Typhoid Conjugate Vaccine (TCV), a phase 3, double-blind, randomized controlled trial was conducted in Lalitpur, Nepal. 20,000 children aged between 9 months and ≤16 years were vaccinated with a new TCV, or control vaccine. Participants were actively followed for safety and efficacy over 2 years through passive surveillance (PS) clinics. Several challenges were encountered during vaccination and PS stemming from misinformation, misconception, and fear around clinical trials in the community. Public engagement (PE) activities were conducted across various tiers moving from decision makers in the first tier; to elected local representatives in the second tier; ending with interaction in community with parents/guardians of the targeted population. Prior and during vaccination, engagement was conducted to inform about the study and discuss the importance of vaccination. Post-vaccination, engagement was conducted to inform about PS clinics, alleviate study concerns and share study updates. Direct and continuous interaction with community stakeholders, including parents/guardians of the targeted population contributed to build trust around the study and community willingness to be involved. It helped to raise awareness, drive away misconceptions, and allowed adaptation according to feedback from community members.
Introduction: Type 1 Diabetes Mellitus (DM1) has reportedly a high proportion of initial presenta... more Introduction: Type 1 Diabetes Mellitus (DM1) has reportedly a high proportion of initial presentation as diabetic ketoacidosis, more in resource-poor settings. This study was designed to assess the demographics and clinical characteristics of DM1 patients as well as their perception of diabetes management in local scenario. Method: This is a cross-sectional study of data collected prospectively by a questionnaire survey among young patients with DM1 presenting to Medical and Paediatric Referral Clinics of Patan Hospital, Nepal during April 2016 to June 2016. Ethical approval was obtained. Demographics, and disease process- initial presentation of diabetic ketoacidosis, HBA1c target, and common problems were analyzed by SPSS using chi-square and Fisher exact tests, p<0.05 considered statistically significant. Result: Fifty-eight patients were enrolled in the study. Diabetic ketoacidosis was the initial presentation in 27(46.55%). A 15(27.78%) of surveyed patients had achieved age...
Typhoid Vi-conjugate vaccines (Vi-TCV) have been developed to control typhoid fever in children i... more Typhoid Vi-conjugate vaccines (Vi-TCV) have been developed to control typhoid fever in children in endemic regions. Previously, in a human challenge model of typhoid, Vi-TCV was administered prior to deliberate ingestion of Salmonella Typhi by healthy adult volunteers in the UK. Vi-specific antibody-dependent neutrophil phagocytosis (ADNP) was associated with protection against enteric fever in this model, but it is not known if ADNP is induced by vaccination of children. We measured ADNP in a cohort of Nepalese children receiving a Vi-TCV in a field study to investigate whether functional antibody responses were also present in children in an endemic setting. Furthermore, we investigated relationships between the functional antibody measures and other properties of the antibody response, including Vi-IgG and IgA titres, and Fc region glycosylation. Antibody-dependent neutrophil phagocytosis significantly increased in children aged 9 months to 15 years between the day of vaccination...
Clinical trials of typhoid conjugate vaccine (TCV) are ongoing in 4 countries. Early data confirm... more Clinical trials of typhoid conjugate vaccine (TCV) are ongoing in 4 countries. Early data confirm safety, tolerability, and immunogenicity of typhoid conjugate vaccine, and early efficacy results are promising. These data support World Health Organization recommendations and planned country introductions. Forthcoming trial data will continue to inform programmatic use of typhoid conjugate vaccine.
Low- and middle-income countries face a high burden of typhoid and paratyphoid fever due to poor ... more Low- and middle-income countries face a high burden of typhoid and paratyphoid fever due to poor water quality and inadequate sanitation. The World Health Organization (WHO) recommends the use of typhoid conjugate vaccines (TCV) in endemic settings and Gavi, the Vaccine Alliance, supports TCV introduction. There are currently 2 WHO-prequalified TCVs with Typbar TCV introduced in Pakistan, Liberia, and Zimbabwe. Countries should assess disease burden and consider introduction of TCV for programmatic use. Several paratyphoid vaccine candidates are in early stages of development. An effective bivalent vaccine would be the most efficient way to control typhoid and paratyphoid fever.
Background: Electronic data capture systems (EDCs) have the potential to achieve efficiency and q... more Background: Electronic data capture systems (EDCs) have the potential to achieve efficiency and quality in collection of multisite data. We quantify volume, time, accuracy and costs of an EDC using large-scale census data from the STRATAA consortium, a comprehensive programme assessing population dynamics and epidemiology of typhoid fever in Malawi, Nepal and Bangladesh to inform vaccine and public health interventions. Results: A census form was developed through a structured iterative process and implemented using Open Data Kit Collect running on Android-based tablets. Data were uploaded to Open Data Kit Aggregate, then auto-synced to MySQL-defined database nightly. Data were backed-up daily from 3 sites centrally, and auto-reported weekly. Pre-census materials costs were estimated. Demographics of 308,348 individuals from 80,851 households were recorded within average of 14.7 weeks range (13-16) using 65 fieldworkers. Overall, 21.7 errors (95% confidence interval: 21.4, 22.0) per...
There is a high risk of occupational exposure to tuberculosis among healthcare workers in endemic... more There is a high risk of occupational exposure to tuberculosis among healthcare workers in endemic countries. Regular screening for tuberculosis among healthcare workers is not carried out in Nepal. Infection control measures are also not routinely implemented. The aim of this study was to determine the prevalence of active tuberculosis among staff/students at Patan Hospital. Participants were given a self-administered questionnaire and invited to undergo chest radiography. Cases were scored and reviewed based on predetermined criteria, and presumptive tuberculosis cases were invited to undergo sputum smear and culture. Participants were categorized according to the extent of patient contact and asked about history of tuberculosis medication. Among 560 participants, 76.8% had direct contact with patients. Fifty-eight (10.4%) gave history of cough >2 weeks. Based on symptom history and chest radiography, 20.0% (n=112) cases were reviewed, and 12.5% (n=14) of those reviewed had sput...
New diagnostic tests for enteric fever are urgently needed to assist with timely antimicrobial tr... more New diagnostic tests for enteric fever are urgently needed to assist with timely antimicrobial treatment of patients and to measure the efficacy of prevention measures such as vaccination. In a novel translational approach, here we use two recently developed controlled human infection models (CHIM) of enteric fever to evaluate an antibody-in-lymphocyte supernatant (ALS) assay, which can detect recent IgA antibody production by circulating B cells in ex vivo mononuclear cell culture. We calculated the discriminative ability of the ALS assay to distinguish diagnosed cases in the two CHIM studies in Oxford, prior to evaluating blood culture-confirmed diagnoses of patients presenting with fever to hospital in an endemic areas of Kathmandu, Nepal. Antibody responses to membrane preparations and lipopolysaccharide provided good sensitivity (>90%) for diagnosing systemic infection after oral challenge with Salmonella Typhi or S. Paratyphi A. Assay specificity was moderate (~60%) due to ...
Invasive infections caused by Salmonella enterica serovar Typhi and Paratyphi A are estimated to ... more Invasive infections caused by Salmonella enterica serovar Typhi and Paratyphi A are estimated to account for 12-27 million febrile illness episodes worldwide annually. Determining the true burden of typhoidal Salmonellae infections is hindered by lack of population-based studies and adequate laboratory diagnostics.The Strategic Typhoid alliance across Africa and Asia study takes a systematic approach to measuring the age-stratified burden of clinical and subclinical disease caused by typhoidal Salmonellae infections at three high-incidence urban sites in Africa and Asia. We aim to explore the natural history of Salmonella transmission in endemic settings, addressing key uncertainties relating to the epidemiology of enteric fever identified through mathematical models, and enabling optimisation of vaccine strategies. Using census-defined denominator populations of ≥100 000 individuals at sites in Malawi, Bangladesh and Nepal, the primary outcome is to characterise the burden of enter...
A 51-year-old man presented with intermittent fever, mild cough and loss of appetite of 1-month d... more A 51-year-old man presented with intermittent fever, mild cough and loss of appetite of 1-month duration. His sputum smear was positive for acid-fast bacilli and his chest radiograph revealed apical infiltrations. The patient was treated with antitubercular therapy (ATT), recovered and was well for 1 month, after which he suddenly developed focal seizures. MRI of the brain with gadolinium enhancement showed high intensity nodular foci in the frontal, parietal and occipital regions. The patient was diagnosed as a case of paradoxical reaction to ATT, and was successfully managed with continued ATT and adjunctive steroid therapy.
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Papers by Mila Shakya