ORCID Profile
0000-0002-3288-6956
Current Organisations
World Bank
,
University of California, Berkeley
,
University of California
,
San Francisco VA Medical Center
,
International School of the Peninsula
,
CHINA CDC
,
Department of Public Health
,
American Board of Internal Medicine
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Publications
Preventive small-quantity lipid-based nutrient supplements reduce severe wasting and severe stunting among young children: an individual participant data meta-analysis of randomized controlled trials
Publisher: Elsevier BV
Date: 11-2022
DOI: 10.1093/AJCN/NQAC232
Characteristics that modify the effect of small-quantity lipid-based nutrient supplementation on child growth: an individual participant data meta-analysis of randomized controlled trials
Publisher: Elsevier BV
Date: 11-2021
DOI: 10.1093/AJCN/NQAB278
Influence of climatic and environmental risk factors on child diarrhea and enteropathogen infection and predictions under climate change in rural Bangladesh
Publisher: Cold Spring Harbor Laboratory
Date: 27-09-2022
DOI: 10.1101/2022.09.26.22280367
Abstract: Understanding pathogen-specific relationships with climate is crucial to informing interventions under climate change. We matched spatiotemporal temperature, precipitation, surface water, and humidity data to data from a trial in rural Bangladesh that measured diarrhea and enteropathogen prevalence in children 0-2 years from 2012-2016. We fit generalized additive models and estimated percent changes in prevalence using projected precipitation under Shared Socio-Economic pathways describing sustainable development (SSP1), middle of the road (SSP2), and fossil fuel development (SSP5) scenarios. An increase from 15°C to 30°C in weekly average temperature was associated with 5.0% higher diarrhea, 6.4% higher Norovirus, and 13.0% higher STEC prevalence. Above-median precipitation was associated with 1.27-fold (95% CI 0.99, 1.61) higher diarrhea higher Cryptosporidium , tEPEC, ST-ETEC, STEC, Shigella , EAEC, C ylobacter, Aeromonas , and Adenovirus 40/41 and lower aEPEC, Giardia , Sapovirus, and Norovirus prevalence. Other associations were weak or null. Compared to the study period, diarrhea prevalence was similar under SSP1 (7%), 3.4% (2.7%, 4.3%) higher under SSP2, and 5.7% (4.4%, 7.0%) higher under SSP5. Prevalence of pathogens responsible for a large share of moderate-to-severe diarrhea in this setting ( Shigella, Aeromonas) were 13-20% higher under SSP2 and SSP5. Higher temperatures and precipitation were associated with higher prevalence of diarrhea and multiple enteropathogens higher precipitation was associated with lower prevalence of some enteric viruses. Under likely climate change scenarios, we projected increased prevalence of diarrhea and enteropathogens responsible for clinical illness. Our findings inform pathogen-specific adaptation and mitigation strategies and priorities for vaccine development. Bill & Melinda Gates Foundation, National Institute of Allergy and Infectious Diseases, National Heart, Lung, And Blood Institute, Stanford University School of Medicine, Chan Zuckerberg Biohub We searched Google Scholar and Scopus for studies published from January 1, 2000 to present using the following three queries: 1) child and diarrhea OR “enteric infection” and meteorological OR environmental OR “surface water” OR “standing water” and risk AND/OR factors 2) Climate AND change AND project* AND diarrhea OR diarrhoea 3) climate AND change AND project* OR model AND enter* AND infect* AND E. coli. Studies generally focused on in idual risk factors for diarrhea transmission or enteric infection, with an emphasis on temperature and precipitation. Studies found that higher temperatures were associated with higher incidence of bacterial diarrhea and lower incidence of viral diarrhea few studies have investigated associations between temperature and parasitic diarrhea. Heavy rainfall, particularly after dry periods, was associated with higher diarrhea prevalence, though heavy rainfall during rainy seasons was found to protect against diarrhea incidence. Similarly, flooding of surface water and shallow wells was also associated with higher diarrhea prevalence. Very few studies investigated associations between diarrhea or enteropathogen carriage and surface water presence, or humidity. A recent in idual participant meta-analysis of studies in 19 low- and middle-income countries found that higher precipitation was associated with a small decrease in enterotoxigenic E. coli (ETEC) and C ylobacter spp. prevalence and no difference in Shigella, Cryptosporidium , or Giardia , or enteric virus prevalence. Weekly average temperature increases of 10-40° C within the study period were associated with higher risk of C ylobacter , ETEC, Shigella, Cryptosporidium, Giardia , and adenovirus, and lower risk of sapovirus and rotavirus, and generally, associations were stronger. Higher humidity was associated with higher risk of enteric bacterial infections and lower risk of enteric virus infection. A small number of studies have projected diarrhea under climate change in low- and middle-income countries. Studies have estimated a 15-20% increase in global diarrhea risk in 2040-2069 relative to 1961-1990, up to 21% increase in diarrhea incidence in northern India from 2013 to the 2040s, 3-10% increase in diarrhea cases in the Gaza Strip associated with 1.5° to 2°C increases in temperature, and an 8% increase in diarrhea burden by 2050 in Nepal. One study estimated an additional 1,625,073 ETEC diarrhea cases in Bangladesh from 2046-2065 due to climate change. No studies estimated changes in the presence of multiple enteropathogens under possible climate change scenarios. This study matched remote sensing data on precipitation, temperature, surface water, and humidity to data on diarrhea and enteropathogen carriage in children under 2 years from a trial in rural Bangladesh. We fit flexible models to investigate potentially non-linear relationships between each climate and environmental risk factor and each health outcome. In addition, we predicted the prevalence of each outcome under three possible climate change scenarios. Our predictions leveraged the spatiotemporal distributions of both climate precipitation projections and diarrhea and enteropathogen carriage in the trial. To our knowledge, this is the first study to predict prevalence under climate change scenarios for both diarrhea and multiple enteropathogens in a rural, low-resource south Asian setting. Our study sheds light on how climate change may impact diarrhea and enteropathogen carriage in Bangladesh, which is highly vulnerable to climate change due to its low altitude and seasonal flooding. We found that both higher temperatures and precipitation were associated with higher diarrhea prevalence, consistent with prior studies. Compared to prior studies, which have primarily found associations between diarrhea and heavy rainfall following a dry period, we found that moderate levels of weekly precipitation were associated with higher diarrhea prevalence. Relationships between climatic and environmental variables and enteropathogen carriage varied by taxa, as other studies have found, but for some pathogens and risk factors, we observed associations in different directions than prior studies. Under middle of the road and fossil fuel-based development climate change scenarios, we projected increased diarrhea prevalence and taxa-specific changes in enteropathogen prevalence. Our findings suggest that climate change may exacerbate diarrhea burden in rural Bangladesh in the absence of sustainable development and inform prioritization of pathogen-specific mitigation and/or adaptation interventions (e.g., vaccines) for young children in rural, South Asian settings under climate change.
Effect of sanitation improvements on soil-transmitted helminth eggs in courtyard soil from rural Bangladesh: Evidence from a cluster-randomized controlled trial
Publisher: Public Library of Science (PLoS)
Date: 03-08-2249
DOI: 10.1371/JOURNAL.PNTD.0008815
Abstract: Improved sanitation has been hypothesized to reduce soil-transmitted helminth (STH) infections by reducing the prevalence and concentration of STH eggs/larvae in soil. We evaluated the effect of a randomized sanitation program (providing households with an improved dual-pit latrine, tools for child/animal feces management, and behavioral messaging) on reducing the prevalence and concentration of STH eggs in soil from household courtyards. We collected soil s les from 1405 households enrolled in the sanitation intervention (n = 419) and control (n = 914) groups of a cluster-randomized controlled trial (WASH Benefits) in rural Bangladesh approximately 2 years after the initiation of the interventions. We analyzed s les for Ascaris lumbricoides , Trichuris trichiura , and hookworm eggs by microscopy. We estimated prevalence ratios (PR) and egg count ratio (ECR) to compare the prevalence of STH eggs and arithmetic and geometric mean egg counts for STH eggs per gram of soil in the sanitation and control arms. Among intervention households, latrines achieved high and sustained user uptake by adults while child open defecation remained common and most households did not dispose of child feces hygienically. In courtyard soil from control households, the prevalence of any STH eggs was 75.7% and the prevalence of any larvated STH eggs was 67.3%. A . lumbricoides was detected in 63.0% of control s les and T . trichiura in 55.7% of control s les hookworm was not detected in any s le. In the control arm, the arithmetic mean egg count for any STH was 3.96 eggs/dry gram, while the geometric mean was 1.58 eggs/dry gram. There was no difference between the intervention and control groups in the prevalence of any STH eggs (PR = 0.98 (95% CI: 0.91, 1.05)) or mean egg counts (ECR = 0.08 (95% CI: -0.10, 0.26) for geometric mean and 0.07 (95% CI: -0.22, 0.37) for arithmetic mean). Adjusted models gave similar results. A compound-level sanitation intervention that provided improved latrines and tools for disposal of child and animal feces did not have an impact on STH eggs in soil. In order to effectively reduce the prevalence and concentration of STH eggs in the environment, sustained, widespread use of sanitation strategies to isolate and hygienically dispose of child and animal feces may need to complement traditional strategies for containment of adult human feces. Trial Registration: NCT01590095 .
Characteristics that modify the effect of small-quantity lipid-based nutrient supplementation on child growth: an individual participant data meta-analysis of randomized controlled trials
Publisher: Cold Spring Harbor Laboratory
Date: 08-02-2021
DOI: 10.1101/2021.02.05.21251105
Abstract: Meta-analyses have demonstrated that small-quantity lipid-based nutrient supplements (SQ-LNS) reduce stunting and wasting prevalence among infants and young children. Identification of subgroups who benefit most from SQ-LNS may facilitate program design. Our objective was to identify study-level and in idual-level modifiers of the effect of SQ-LNS on child growth outcomes. We conducted a two-stage meta-analysis of in idual participant data from 14 randomized controlled trials of SQ-LNS provided to children 6 to 24 months of age in low- and middle-income countries (n=37,066). We generated study-specific and subgroup estimates of SQ-LNS vs. control and pooled the estimates using fixed-effects models, with random-effects models as sensitivity analyses. We used random effects meta-regression to examine study-level effect modifiers. Heterogeneity was assessed using I 2 and Tau 2 statistics. Sensitivity analyses were conducted to examine whether results differed depending on inclusion criteria for arms within trials and types of comparisons. SQ-LNS provision decreased stunting (length-for-age z-score −2) by 12% (relative reduction), wasting (weight-for-length (WLZ) z-score −2) by 14%, low mid-upper arm circumference (MUAC 125 mm or MUACZ −2) by 18%, acute malnutrition (WLZ −2 or MUAC 125 mm) by 14%, underweight (weight-for-age z-score −2) by 13%, and small head size (head-circumference z-score −2) by 9%. Effects of SQ-LNS on growth outcomes generally did not differ by study-level characteristics including region, stunting burden, malaria prevalence, sanitation, water quality, duration of supplementation, frequency of contact or average reported compliance with SQ-LNS. Effects of SQ-LNS on stunting, wasting, low MUAC and small head size were greater among girls than among boys effects on stunting, underweight and low MUAC were greater among later-born (vs. first-born) children and effects on wasting and acute malnutrition were greater among children in households with improved (vs. unimproved) sanitation. Results were similar across sensitivity analyses. The positive impact of SQ-LNS on growth is apparent across a wide variety of study-level contexts. Policy-makers and program planners should consider including SQ-LNS in the mix of interventions to prevent both stunting and wasting. This study was registered at www.crd.york.ac.uk/PROSPERO as CRD42019146592.
Evaluation of an on-site sanitation intervention against childhood diarrhea and acute respiratory infection 1 to 3.5 years after implementation: Extended follow-up of a cluster-randomized controlled t
Publisher: Public Library of Science (PLoS)
Date: 08-08-2022
DOI: 10.1371/JOURNAL.PMED.1004041
Abstract: Diarrhea and acute respiratory infection (ARI) are leading causes of death in children. The WASH Benefits Bangladesh trial implemented a multicomponent sanitation intervention that led to a 39% reduction in the prevalence of diarrhea among children and a 25% reduction for ARI, measured 1 to 2 years after intervention implementation. We measured longer-term intervention effects on these outcomes between 1 to 3.5 years after intervention implementation, including periods with differing intensity of behavioral promotion. WASH Benefits Bangladesh was a cluster-randomized controlled trial of water, sanitation, hygiene, and nutrition interventions (NCT01590095). The sanitation intervention included provision of or upgrades to improved latrines, sani-scoops for feces removal, children’s potties, and in-person behavioral promotion. Promotion was intensive up to 2 years after intervention initiation, decreased in intensity between years 2 to 3, and stopped after 3 years. Access to and reported use of latrines was high in both arms, and latrine quality was significantly improved by the intervention, while use of child feces management tools was low. We enrolled a random subset of households from the sanitation and control arms into a longitudinal substudy, which measured child health with quarterly visits between 1 to 3.5 years after intervention implementation. The study period therefore included approximately 1 year of high-intensity promotion, 1 year of low-intensity promotion, and 6 months with no promotion. We assessed intervention effects on diarrhea and ARI prevalence among children years through intention-to-treat analysis using generalized linear models with robust standard errors. Masking was not possible during data collection, but data analysis was masked. We enrolled 720 households (360 per arm) from the parent trial and made 9,800 child observations between June 2014 and December 2016. Over the entire study period, diarrheal prevalence was lower among children in the sanitation arm (11.9%) compared to the control arm (14.5%) (prevalence ratio [PR] = 0.81, 95% CI 0.66, 1.00, p = 0.05 prevalence difference [PD] = −0.027, 95% CI −0.053, 0, p = 0.05). ARI prevalence did not differ between sanitation (21.3%) and control (22.7%) arms (PR = 0.93, 95% CI 0.82, 1.05, p = 0.23 PD = −0.016, 95% CI −0.043, 0.010, p = 0.23). There were no significant differences in intervention effects between periods with high-intensity versus low-intensity/no promotion. Study limitations include use of caregiver-reported symptoms to define health outcomes and limited data collected after promotion ceased. The observed effect of the WASH Benefits Bangladesh sanitation intervention on diarrhea in children appeared to be sustained for at least 3.5 years after implementation, including 1.5 years after heavy promotion ceased. Existing latrine access was high in the study setting, suggesting that improving on-site latrine quality can deliver health benefits when latrine use practices are in place. Further work is needed to understand how latrine adoption can be achieved and sustained in settings with low existing access and how sanitation programs can adopt transformative approaches of excreta management, including safe disposal of child and animal feces, to generate a hygienic home environment. ClinicalTrials.gov NCT01590095 t2/show/NCT01590095 .
Effect of sanitation improvements on soil-transmitted helminth eggs in courtyard soil from rural Bangladesh: Evidence from a cluster-randomized controlled trial
Publisher: Cold Spring Harbor Laboratory
Date: 29-09-2020
DOI: 10.1101/2020.09.29.318097
Abstract: Improved sanitation has been hypothesized to reduce soil-transmitted helminth (STH) infections by reducing the prevalence and abundance of STH eggs/larvae in soil. We evaluated the effect of a randomized sanitation program (providing households with an improved dual-pit latrine, tools for child/animal feces management, and behavioral messaging) on reducing STH eggs in soil from household courtyards. We collected soil s les from 1405 households enrolled in the sanitation intervention (n=419) and control (n=914) groups of a cluster-randomized controlled trial (WASH Benefits) in rural Bangladesh approximately 2 years after the initiation of the interventions. We analyzed s les for Ascaris lumbricoides, Trichuris trichiura , and hookworm eggs by microscopy. We estimated prevalence ratios (PR) and relative egg count reductions (ECR) to compare the prevalence of any STH eggs and arithmetic and geometric mean egg counts for any STH per gram of soil between the sanitation and control arms. Among intervention households, latrines achieved high and sustained user uptake by adults while child open defecation remained common and most households did not dispose of child feces hygienically. In courtyard soil from control households, the prevalence of any STH eggs was 75.7% and the prevalence of any larvated STH eggs was 67.3%. A. lumbricoides was detected in 63.0% of control s les and T. trichiura in 55.7% of control s les hookworm was not detected in any s le. The arithmetic mean egg count for any STH was 3.96 eggs/dry gram, while the geometric mean was 1.58 eggs/dry gram. There was no difference between the intervention and control groups in the prevalence of any STH eggs (PR=0.98 (95% CI: 0.91–1.05)) or mean egg counts (ECR=0.08 (95% CI: −0.10, 0.26) for geometric mean and 0.07 (95% CI: −0.22, 0.37) for arithmetic mean). Adjusted models gave similar results. A compound-level sanitation intervention that provided improved latrines and tools for disposal of child and animal feces did not have an impact on environmental reservoirs of STH eggs. In order to effectively reduce the prevalence and abundance of STH eggs in the environment, sustained, widespread use of sanitation strategies to isolate and hygienically dispose of child and animal feces may need to complement traditional strategies for containment of adult human feces. Improved sanitation has been hypothesized to reduce soil-transmitted helminth (STH) infections by reducing the prevalence and abundance of STH eggs/larvae in soil. We evaluated the effect of a randomized sanitation program (providing households with an improved dual-pit latrine, tools for child/animal feces management, and behavioral messaging) on reducing STH eggs in soil from household courtyards. We collected soil s les from 1405 households enrolled in the control and sanitation groups of a cluster-randomized controlled trial (WASH Benefits) in rural Bangladesh approximately 2 years after the initiation of the interventions. We analyzed s les for Ascaris lumbricoides, Trichuris trichiura and hookworm eggs by microscopy. We found no effect of the sanitation intervention on STH eggs in soil. In order to effectively reduce the prevalence and abundance of STH eggs in the environment, sustained, widespread use of sanitation strategies to isolate and hygienically dispose of child and animal feces may need to complement traditional strategies for containment of adult human feces.
Preventive small-quantity lipid-based nutrient supplements reduce severe wasting and severe stunting among young children: an individual participant data meta-analysis of randomized controlled trials
Publisher: Cold Spring Harbor Laboratory
Date: 17-06-2022
DOI: 10.1101/2022.06.16.22276521
Abstract: Meta-analyses show that small-quantity lipid-based nutrient supplements (SQ- LNS) reduce child wasting and stunting. There is little information regarding effects on severe wasting or stunting. We aimed to identify the effect of SQ-LNS on severe wasting (weight-for-length z- score −3) and severe stunting (length-for-age z-score −3). We conducted a two-stage meta-analysis of in idual participant data from 14 randomized controlled trials of SQ-LNS provided to children 6 to 24 mo of age. We generated study-specific and subgroup estimates of SQ-LNS vs. control and pooled the estimates using fixed-effects models. We used random effects meta-regression to examine study-level effect modifiers. In sensitivity analyses, we examined whether results differed depending on study arm inclusion criteria and types of comparisons. Q-LNS provision led to a relative reduction of 31% in severe wasting (Prevalence Ratio, PR 0.69 (0.55, 0.86), n=34,373) and 17% in severe stunting (PR 0.83 (95% CI: 0.78, 0.90), n=36,795). Results were similar in most of the sensitivity analyses but somewhat attenuated when comparisons using passive control arms were excluded: PR 0.74 (0.57, 0.96), n=26,327 for severe wasting and PR 0.88 (0.81, 0.95), n=28,742 for severe stunting. Study-level characteristics generally did not significantly modify the effects of SQ-LNS, but results suggested greater effects of SQ-LNS in sites with greater burdens of wasting or stunting, or with poorer water quality or sanitation. Including SQ-LNS in preventive interventions to promote healthy child growth and development is likely to reduce rates of severe wasting and stunting. Registered at www.crd.york.ac.uk/PROSPERO as CRD42019146592.
Related Organisations
University Of California, San Francisco
Location: United States of America
University Of California, San Diego
Location: United States of America
University Of California, Berkeley
Location: United States of America
US Environmental Protection Agency
Location: United States of America
University Of California Berkeley, University Of California Davis
Location: United States of America
University Of California San Francisco School Of Medicine
Location: United States of America
Stanford University School Of Medicine
Location: United States of America
International School Of The Peninsula
Location: United States of America
American Board Of Internal Medicine
Location: United States of America
American Water Works Research Foundation
Location: United States of America
Related Funding Activities
No related grants have been discovered for John Colford.