International Journal of Hygiene and Environmental Health

Leptospirosis is a globally important environmentally transmitted disease, with approximately one million cases and 60,000 deaths reported annually. In low-income urban communities, inadequate sanitation, drainage and waste management may increase human exposure to contaminated environments. This study investigated the influence of environmental engineering risk factors on Leptospira exposure in four disadvantaged urban communities (favelas) in Salvador, Brazil. A high-precision georeferenced field survey was developed to identify, map and characterise sanitation, stormwater drainage and solid waste infrastructure. Cross-sectional spatial analyses of baseline data were used to assess associations between environmental risk factors and the residential locations of individuals with anti-Leptospira antibodies. Seropositive individuals tended to reside closer to environmental risk factors and at lower relative elevations. Density analyses indicated that seropositive individuals tended to reside closer to inadequate or partially adequate sewerage components than to sewage-contaminated streams or open sewage points. Inadequate streets showed also showed high density peaks, suggesting that exposure may occur through frequent contact with contaminated runoff and standing water. In contrast, open waste dumping sites and vacant lots showed weaker and more diffuse spatial patterns. The findings highlight the importance of infrastructure quality shaping leptospirosis risk within urban informal settlements. The proposed methodology provides a practical approach for high-resolution characterisation of environmental exposure pathways and may support targeted engineering interventions and epidemiological investigations of leptospirosis and other environmentally transmitted diseases.

Summary Background: Wastewater and environmental surveillance (WES) enables community-level monitoring of infectious diseases. Most progress has focused on sewer-based surveillance, yet nearly half of the global population relies on non-sewered sanitation. In non-sewered settings, urban drainage channels have been used for poliovirus environmental surveillance, but their potential for a multi-pathogen WES with spatially defined catchments, and comparability to sewer-based surveillance, remains under-explored. Methods: Ten drainage channel sampling points with delineated micro-catchments (0.95-3.83 km2 with 12,885-44,146 people) were selected within Kampala. A total of 255 drainage channel and 54 wastewater treatment plant (WWTP) influent samples were collected during two campaigns in March and September-October 2025. A multi-target panel was quantified by digital PCR, including enteric viruses (Norovirus GI and GII, Rotavirus), respiratory viruses (SARS-CoV-2, Influenza A and B viruses, Respiratory Syncytial Virus (RSV)), non-O1/O139 Vibrio cholerae (V. cholerae), and Pepper Mild Mottle Virus (PMMoV) as a fecal indicator. Findings: Enteric viruses, non-O1/O139 V. cholerae, and PMMoV were consistently detected across all drainage channels and WWTP influents. Concentrations were generally lower in drainage than WWTP influents, except for non-O1/O139 V. cholerae. When normalized by PMMoV, concentrations across most drainage channels were comparable to WWTP influents, although comparability varied by target and location. Both concentrations and PMMoV-normalized concentrations varied across sampling locations. Trends between campaigns varied by pathogen target and were not explained by any single micro-catchment characteristic. Influenza A virus was the most frequently detected respiratory virus (8-23% in drainage channels; 3-10% in WWTP influents), while SARS-CoV-2, Influenza B, and RSV were rarely detected. Interpretation: PMMoV-normalized concentrations across most micro-catchments were comparable to WWTP influents, with spatial heterogeneity implying neighborhood-level differences in disease prevalence. Catchment-delineated drainage surveillance has potential to offer spatially resolved public health information in non-sewered settings comparable to sewer-based wastewater monitoring. Funding: Eawag Discretionary Funding

Household environments in low-resource settings can become contaminated with fecal matter from multiple sources, including humans and domestic animals. Identifying the source of fecal contamination is critical for designing targeted interventions to reduce exposure to enteric pathogens, particularly for young children who bear the majority of the enteric disease burden. Using data from 140 households with children enrolled in the ECoMiD cohort study in northwestern coastal Ecuador, we (1) characterized source-specific fecal contamination in samples from household floors and maternal and child hands, and (2) identified animal-related and Water, Sanitation and Hygiene (WASH) conditions associated with the presence and concentrations of these markers. We used five qPCR-based microbial source tracking (MST) markers to detect fecal contamination from avian (GFD), canine (DG37), swine (Pig2Bac), ruminant (Rum2Bac), and human (HF183) sources. Prevalence ratios (PR) and mean differences comparing the presence/absence and concentration, respectively, of MST markers between households with and without each animal-related or WASH condition were estimated using generalized linear models with Poisson and Gaussian distributions. Animal MST markers tracked strongly with several animal-related conditions, whereas associations between the human MST marker and household demographic and WASH conditions were more limited. Animal ownership (PR 1.53; 95% CI: 1.04-2.26) was associated with higher prevalence of animal MST markers on floors. Households reporting animal feces indoors had higher prevalence of animal MST markers on floors (PR 1.84; 95% CI: 1.17-2.89), and higher concentrations of animal MST markers on child hands (mean difference 0.27 gene copies (gc)/m2; 95% CI: 0.12-0.41) and maternal hands (mean difference 0.10 gc/m2; CI: 0.02-0.18). Animal feces left unremoved outside the home were associated with higher prevalence of animal MST markers on maternal hands (PR 2.31; 95% CI: 1.11-4.81). Mothers reporting direct contact with animals had higher concentrations of animal MST markers on their children hands (mean difference 0.12 gc/m2; 95% CI: 0.02-0.21). Higher FECEZ scores, an overall metric for animal exposure, were associated with higher prevalence of animal MST markers on maternal hands (PR 2.94; 95% CI: 1.17-7.40). For human fecal contamination, the presence of E. coli on child hands was associated with higher prevalence of human MST markers on floors (PR 1.30; 95% CI: 1.00-1.68). Our findings reinforce household floors and maternal and child hands as key reservoirs of fecal contamination and point to future potential targets worth exploring for interventions in similar high-burden settings.

Intermittent water supplies (IWS) serve >1 billion people globally and can transmit waterborne infections. How often and for how long supply is delivered varies between and within IWS systems. The UN Sustainable Development Goals target having water available when needed for >=12 hours/day or >=4 days/week but there are scarce data on how supply frequency/duration within IWS affect health outcomes. We conducted a matched study in Hubli-Dharwad, India, a city served partially by continuous water supply (CWS) since 2007 and partially by IWS. We enrolled 2220 CWS and 2218 IWS households matched on socioeconomics and sanitation. We compared diarrhea prevalence in children <5 years and typhoid fever incidence between households with different water supply characteristics using generalized linear models with robust standard errors and adjusting for socio-demographics and sanitation. Among IWS households, the median supply frequency was every 8 days (interquartile range [IQR]=7-8), and the median supply duration was 4 hours (IQR=3-5). IWS households had 36% higher prevalence of child diarrhea (prevalence ratio [PR]=1.36, 1.00-1.84) and 78% more typhoid fever cases (cumulative incidence ratio [CIR]=1.78, 1.05-3.02) than CWS households. IWS households meeting the UN criterion and those in the top quintiles of supply frequency and duration (receiving water once every 1-6 days or for 7-24 hours per supply cycle) had similar health outcomes as CWS households. IWS households below the UN criterion had higher diarrhea prevalence (PR=1.41, 1.03-1.93) and more typhoid fever cases (CIR=1.93, 1.15-3.22) than CWS households, as well as more typhoid fever cases than IWS households meeting the criterion (CIR=3.66, 1.37-9.79). IWS households in the bottom quintiles of supply frequency and duration (receiving water once every 9-15 days or for <=3 hours per supply cycle) had 45-72% higher child diarrhea prevalence and twice as many typhoid fever cases than CWS households (p-values<0.05). These findings support global efforts to implement CWS. Our results also highlight that increasing supply frequency and duration in IWS systems in the interim can deliver health benefits, and the UN criterion of having water available when needed improves health.

Boiling raw milk before drinking is a common practice in Bangladesh, but its impact on residue levels of ciprofloxacin and enrofloxacin is not well known. This study looked at these antibiotics in 120 raw cow milk samples from 12 dairy areas near Dhaka, collected between November 2023 and March 2024. Each sample was split into two parts: one tested as raw milk and the other after boiling at home for 15 minutes. Residues were checked using matrix-matched HPLC-UV. Ciprofloxacin and enrofloxacin were found in 113 out of 120 samples (94.2%), and at least one of them was present in 117 samples (97.5%). We considered a level of 12.5 micrograms per liter or higher as detected. The average combined amount of these antibiotics dropped from 194.61 micrograms per kilogram in raw milk to 179.57 micrograms per kilogram after boiling, a decrease that was statistically significant (p < 0.001). However, the percentage of samples exceeding the EU maximum residue limit of 100 micrograms per kilogram only went down from 92.5% in raw milk to 90.0% after boiling, which was not statistically significant (p = 0.250). Using national milk consumption data as an estimate of intake, the hazard index for adults was 0.360 for raw milk and 0.332 for boiled. Calculated with a 10 kg body weight, these values were 2.159 and 1.992, respectively. Overall, boiling at home did reduce the levels of ciprofloxacin and enrofloxacin, but it usually did not bring high-residue samples below the EU limit.

In low-income countries, ESBL-producing Escherichia coli (ESBL-EC) is frequently detected in humans, animals and household environments, indicating widespread exposure to antimicrobial resistance (AMR). Established risk factors such as antibiotic use do not explain the high community carriage of AMR in all settings; identifying the dominant exposure pathways can inform interventions against AMR. We aimed to investigate (i) animal-human-environment sharing of AMR by assessing associations between the abundance of ESBL-EC in the household environment, domestic animal feces and young children's stool and (ii) household factors associated with ESBL-EC abundance in these reservoirs. We enrolled 112 households from the CRADLE trial in rural Bangladesh. We enumerated ESBL-EC in drinking water, food, child hand rinses, outdoor soil, indoor floor swabs, chicken and cow feces, and stool from children aged 6 months. We recorded indicators of sanitation, animal ownership/management, human and animal antibiotic use, and child exposure behaviors using structured questionnaires and spot checks. The highest prevalence of ESBL-EC was in child stool (95.6%) and animal feces (82.3-96.9%), followed by soil (48.2%) and floors (36.6%); < 10% of food, child hands and drinking water harbored ESBL-EC. The abundance of ESBL-EC in child stool was not associated with its abundance in any sampled matrix; the abundance in chicken but not cow feces showed positive correlations with soil, floors, child hands, and drinking water (correlation coefficients: 0.19-0.39, p-values < 0.05). Higher-quality latrines (improved, pour-flush, with slab) were associated with lower ESBL-EC abundance across matrices; unsafe animal management (animals roaming or spending the night inside the home) was associated with higher abundance. Child antibiotic use and exposure behaviors (soil ingestion, time spent on floor) were not associated with ESBL-EC abundance in child stool. We observed high AMR colonization among young children and domestic animals in rural Bangladesh not explained by traditional fecal-oral exposure pathways. Future studies should explore additional pathways and assess whether sanitation and animal management improvements can reduce AMR.

Wastewater-based epidemiology (WBE) has emerged as a powerful population-level surveillance tool, but its coverage is structurally concentrated in in-network urban areas, potentially leaving rural populations underrepresented. Routine human movement between sewered (in-network) and unsewered (off-network) areas may, however, cause wastewater treatment plant (WWTP) measurements to reflect infectious disease dynamics beyond sewer boundaries. We evaluated this hypothesis using daily clinical COVID-19 testing data (January 2021-April 2022) across New York State excluding New York City (NYC). We disaggregated weekly cases and tests into in-network (WWTP catchment area) and off-network (outside WWTP catchment area) components applied to two geographic frameworks: administrative counties (N = 53 mixed-coverage) and mobility-defined communities identified through Walktrap community detection applied to census tract-level movement networks (N = 32 mixed-coverage). In/off-network COVID-19 trends were strongly correlated under both frameworks. County-level statewide aggregate correlations were high (incidence r = 0.994, positivity r = 0.996), as were individual county correlations (median r = 0.909 and 0.932, respectively). Mobility-defined community-level statewide correlations were similarly strong (r = 0.990 and 0.992), with comparable unit-level medians (r = 0.877 and 0.894). The mobility-defined community framework provided better population balance between in-network and off-network strata (87.5% vs. 69.8% in balanced range) and a higher floor on representativeness (minimum r = 0.440 vs. 0.177). Population size was the dominant predictor of in-network/off-network alignment at both scales; wastewater infrastructure density and off-network signal variability provided additional explanatory power at the mobility-defined community level. WWTPs broadly represent COVID-19 dynamics in surrounding off-network populations, supporting their use as sentinel surveillance sites. Representativeness weakens in smaller, more rural communities, and mobility-defined communities provide a complementary framework for identifying where this occurs.

Background: Population-based biomonitoring of contemporary-use pesticides remains limited in the United States, particularly in rural agricultural regions, and few studies have repeated measurements within the same individuals over time. Methods: We analyzed 28 urinary pesticide-related biomarkers among 600 adults from the population-based Survey of the Health of Wisconsin with archived urine collected during 2008-2016; 296 participants provided repeat urine and updated exposure information in 2025. Detection frequencies, co-detection, and within-person detection patterns were characterized. Generalized estimating equations were used for stacked, repeated-measures analyses of factors associated with detection of aminomethylphosphonic acid (AMPA), glyphosate, 2,4-dichlorophenoxyacetic acid (2,4-D), and any of these three. Prospective-only analyses evaluated more detailed agricultural and recent exposure measures. Results: Glyphosate, AMPA, and 2,4-D were detected in 7.7%, 6.2%, and 4.3% of retrospective specimens and 5.4%, 3.1%, and 4.1% of prospective specimens, respectively. Co-detection and persistent detection across the 9 to 17-year interval was rare. In repeated-measures models, greater fruit and vegetable intake, older age, and male sex were associated with higher 2,4-D detection. Lower household income was associated with lower AMPA detection, while afternoon/evening collection was associated with higher AMPA detection. In prospective analyses, working on field-crop agricultural land showed the strongest agricultural associations, particularly for 2,4-D and detection of any of the three pesticides. Associations were not seen with self-reported conventional versus organic produce consumption. Conclusions: Urinary pesticide detections were generally infrequent in this Wisconsin population. Diet and direct agricultural activities may be more informative exposure pathways than residing near cropland or private well drinking-water characteristics.

Background Hand hygiene is a core component of infection prevention and control, yet evidence on the effectiveness of hand hygiene interventions in health-care facilities in low-income and middle-income countries has not been comprehensively synthesized alongside implementation barriers and enablers. We assessed the effectiveness of hand hygiene interventions in these settings and examined implementation conditions shaping success. Methods We conducted a systematic review drawing on a University of North Carolina evidence map of environmental health services in low-income and middle-income country health-care facilities, which searched PubMed, Scopus, and Global Health and was supplemented by hand-searching. Hand-hygiene-specific records were restricted to peer-reviewed English-language studies published between Jan 1, 2015, and Nov 28, 2025; backward citation chasing identified additional eligible records. Random-effects meta-analysis was done for studies with extractable pre-intervention and post-intervention hand hygiene compliance data. Other outcomes were synthesized using effect-direction methods. Barriers and enablers were synthesized thematically. The protocol was registered with PROSPERO, CRD420251252831. Findings We screened 656 records and included 57 studies from 32 low-income and middle-income countries. Fifteen studies contributed to meta-analysis. Hand hygiene interventions were associated with higher post-intervention than pre-intervention compliance (pooled risk ratio 1{middle dot}45, 95% CI 1{middle dot}20-1{middle dot}74), with substantial heterogeneity (I2=98%). Most studies used non-randomized designs. Multimodal WHO-style strategies and system-change interventions focused on alcohol-based hand rub availability, placement, or related infrastructure were the most common intervention categories. Effect-direction synthesis suggested favorable effects for compliance and system-related outcomes, whereas evidence for reductions in health-care-associated infections was less consistent. Common barriers included supply shortages, weak audit and data systems, staffing and workload pressures, and WASH infrastructure constraints; common enablers included training, monitoring and feedback, leadership support, reliable supplies, and implementation support. Conclusion Hand hygiene interventions can improve observed compliance in low-income and middle-income country health-care facilities, but sustained gains depend on system supports that make hand hygiene feasible at the point of care. Programs should pair training and behavior-change strategies with reliable supplies, functional WASH infrastructure, audit-and-feedback routines, leadership accountability, and protected implementation time.

Background: Children spend more than 90% of their time indoors, and early childhood education settings (ECEs) are an understudied, high-occupant-density indoor microenvironment where exposure to volatile organic compounds, particulate matter, and other toxicants has been documented. Limited knowledge exists on ECE-specific exposures affecting young children and how they compare to exposures in the home. Methods: This prospective, repeated-measures pilot study targeted enrollment of 44 preschool-aged children and 8 ECE staff across two geographically and sociodemographically distinct ECEs in metropolitan Atlanta, Georgia. Paired silicone wristbands, one home-designated and one ECE-designated, were exchanged between settings across three consecutive days and nights beginning at enrollment to characterize microenvironment-specific exposure. A single spot urine sample was also collected from each child. Continuous indoor air quality monitoring was conducted in two classrooms per site. Caregivers and ECE staff completed structured questionnaires assessing home and ECE environmental characteristics, child respiratory risk, and protocol feasibility and acceptability. Feasibility was evaluated using eight pre-specified indicators spanning recruitment and enrollment, wristband wear duration and loss by microenvironment, urine sample collection completeness, and survey completion by instrument and respondent group. Conclusion: This pilot will establish feasibility and acceptability parameters for a paired, multi-matrix silicone wristband protocol across home and ECE microenvironments. Findings will inform the design, sample size, and power calculations for a subsequent study testing indoor air interventions and pediatric respiratory outcomes in ECEs. Feasibility outcomes are reported in a companion manuscript.

Background Severe acute malnutrition (SAM) affects approximately 12 million children globally. The aim of this study was to assess the effectiveness of integrating a household water treatment and hygiene promotion intervention within the national protocol of Senegal for outpatient treatment of children aged 6-59 months of age with uncomplicated SAM. Methods This was a pragmatic cluster-randomised controlled trial with health centres allocated 1:1 to receive either the standard protocol alone or the standard protocol with the addition of the water treatment and hygiene intervention. The primary outcome of the trial was SAM recovery defined under the national protocol in Senegal, and the secondary outcomes were weight gain, referral to inpatient care, enteric pathogen detection, diarrhoea, and all-cause mortality. Participants were followed up over eight weeks. Findings Between 22 December 2021 and 20 February 2023, 2411 children were enrolled in the study with 777 defaulting outpatient treatment during eight weeks of follow-up. There was no difference between control and intervention groups in the proportion of children recovering from SAM eight weeks post admission (39.8% vs 41.2%; adjusted odds ratio [aOR]: 0.97, 95% Confidence Interval [CI]: 0.66, 1.48). There was no difference in weight gain, referral, enteric pathogen detection or mortality between groups. The prevalence of diarrhoea at eight weeks follow-up was higher in the control group (20.0%) than the intervention group (12.5%), with evidence for a large difference between arms, accounting for between-group differences at baseline (aOR: 0.36; 95%CI: 0.26, 0.50). Interpretation The integration of household water treatment and hygiene promotion in the standard national protocol did not improve SAM recovery nor the related outcomes of weight gain, referral, enteric pathogen detection or mortality but did reduce diarrhoea. Our results suggest that the integration of this intervention to the standard protocol would not improve SAM outcomes in this setting but would potentially reduce the burden of diarrhoea among this vulnerable group. Funding This study was supported by the Bureau of Humanitarian Assistance of the United States Agency for International Development and the ACF Foundation.

Diarrheal disease remains a leading cause of morbidity and mortality among children under five globally, with poor sanitation and hygiene accounting for over 88% of diarrhea and malnutrition burden. In Kenya, diarrhea ranks third in under-five mortality, particularly affecting arid and semi-arid regions. School-Led Total Sanitation (SLTS), adapted from Community-Led Total Sanitation (CLTS), uses pupils as change agents for household hygiene knowledge transfer. However, SLTS effectiveness in addressing diarrhea and malnutrition has not been evaluated in Kenya. This study assessed SLTS effects on diarrheal disease and nutritional outcomes among children aged 5-59 months in Baringo County. A pre- and post-test quasi-experimental design with nonequivalent control groups was employed in Mogotio (intervention) and Baringo South (control) sub-counties. Using multistage sampling, 440 children aged 6-59 months were enrolled. The six-month SLTS intervention included capacity building, school health club formation, triggering activities using Participatory Rural Appraisal tools, Information, Education, and Communication materials distribution, continuous sensitization, and household monitoring. Data were collected at baseline and three months post-intervention using electronic questionnaires and anthropometric measurements. Nutritional status was assessed using WHO Anthro software z-scores for length/height-for-weight (HWZ), and weight-for-age (WAZ) to determine wasting, and underweight prevalence. Chi-square analysis assessed intervention-control differences. Baseline and endline socio-demographic characteristics were comparable between groups. At endline, no significant nutritional outcome differences were observed: wasting prevalence was at 15.0% versus 16.4% ({chi}{superscript 2}=0.155, df=1, p=0.694) while underweight was 12.3% versus 13.6% ({chi}{superscript 2}=0.181, df=1, p=0.670). However, diarrheal disease prevalence significantly reduced in intervention versus control groups: 5.9% versus 13.2% ({chi}{superscript 2}=6.738, df=1, p=0.009), representing a 53% reduction. SLTS intervention showed no significant effect on nutritional outcomes but demonstrated a significant reduction in diarrheal disease among children aged 6-59 months. These findings provide strong evidence for integrating school-based sanitation and hygiene approaches into broader public health strategies addressing diarrheal diseases.

Plastic products have greatly improved convenience in daily life. However, diverse pollutants released from these materials pose substantial risks to human health. Lactiplantibacillus plantarum PD01 has previously been demonstrated to reduce microplastic (MP) bioaccumulation and toxicity in murine model. In this study, we conducted a randomized, double-blind, placebo-controlled trial to further evaluate the efficacy of L. plantarum PD01 in reducing MPs and MP-associated chemicals in humans. A total of 106 participants were recruited in November 2025. Eligible participants were randomly assigned to either the placebo or intervention group, and orally received placebo or 1.0x1010 colony-forming units (CFU) L. plantarum PD01 after meals three times a day, respectively. Fecal, urinary, and blood samples were collected to determine the MPs contents, plasticizer levels, gut microbiota composition, blood metabolic profiles and biochemical indicators. Among these measurements, the analysis of urinary phthalate metabolites was completed first and revealed a significant reduction after the probiotic intervention. Compared with the placebo group, 6-week L. plantarum PD01 supplementation resulted in significant relative reductions in urinary levels of MCMHP by 60.2% (P = 0.0343), MMP by 51.2% (P < 0.001), MEHP by 49.6% (P = 0.0058), MiBP by 45.7% (P = 0.0085), MnBP by 35.8% (P = 0.0478), and {Sigma}DEHP by 46.2% (P = 0.0461). The interim results presented here provide the first clinical evidence that the probiotic strain PD01 can significantly reduce residual MP-associated chemicals in human body. To the best of our knowledge, this is the first randomized controlled trial (RCT) to evaluate probiotic intervention targeting MPs and MP-associated chemicals in humans.

Objective: Over the past decades, US policies intended to reduce air pollution emissions from electric generating units (EGUs), mobile sources (e.g., cars and trucks), and port activities have been implemented to improve air quality. This study aimed to estimate and compare counterfactual air pollution concentrations (i.e., concentrations that would have occurred without these policies) to observed concentrations, and then evaluate the health impacts of such policies in New York City, Los Angeles, and Atlanta from 2005 to 2019. Materials and Methods: We obtained data on respiratory emergency department (ED) visits and cardiovascular disease ED visits that result in hospitalizations for the three cities from 2005-2019. Daily concentrations of fine particulate matter (PM2.5), criteria gases [carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3)], and 1-in-3-day measured concentrations of PM2.5 components and PM sources estimated using positive matrix factorization were acquired from six monitoring sites in the three cities. To estimate health impacts of selected EGU, mobile, and port policies we estimated: 1) counterfactual daily pollutant concentrations at each of the 6 city-sites; 2) associations between daily pollutant concentrations and rates of cardiorespiratory visits using city-site specific multi-pollutant Poisson models; and 3) the percent of cardiorespiratory visits prevented by the implementation of the selected policies, through applying observed and counterfactual concentrations to the fitted health models. Results: Air quality policies were estimated to reduce ambient pollutant concentrations across the three cities, with median PM2.5 reductions of 27%-62% due to all policies combined during 2005-2019. Changes in criteria-pollutant concentrations associated with the selected policies were estimated to avert 7.1% (95% UI: 5.4%, 8.9%) of respiratory visits in New York City, 2.4% (95% UI: 1.4%, 3.4%) in Los Angeles, and 4.5% (95% UI: 0.8%, 8.2%) in Atlanta. In addition, 2.6% (95% UI: 0.9%, 4.2%) and 1.2% (95% UI: 0.3%, 2.1%) of cardiovascular visits were averted in New York City and Los Angeles, while the estimate in Atlanta did not indicate cardiovascular visits averted. Conclusion: The selected EGU, mobile-source, and port policies evaluated during 2005-2019 were estimated to reduce ambient pollutant concentrations and avert respiratory visits in all three cities and cardiovascular visits in New York City and Los Angeles.

Urban air pollution remains a significant public health concern, contributing to premature deaths and adverse health outcomes. However, there is little causal research evaluating the effectiveness of policies designed to improve air quality. This study assesses the impact of all three stages of London's Ultra Low Emission Zone (ULEZ) on air pollution, via PM2.5 levels, and respiratory health, via prescription records for bronchodilator and respiratory corticosteroid medications. Analyses are at general practice level, using a generalised synthetic control method to estimate causal impacts. Stage 1 was associated with a statistically significant but negligible 0.77% reduction in PM2.5 levels, with no corresponding change in prescribing. Stage 2 produced a paradoxical 2.69% increase in PM2.5, alongside a 4.44% decrease in inhaled corticosteroid quantity but a 12.51% increase in average daily quantity (ADQ) usage, suggesting a worsening of disease severity among existing patients. Stage 3 yielded a 2.69% PM2.5 reduction and a modest 2.18% decrease in bronchodilator ADQ usage. Spillover effects beyond the ULEZ boundary were statistically significant, but negligible. We find overall that the ULEZ had minimal effects on both air quality and respiratory prescribing across all three stages. These findings provide new insights into the effectiveness of ULEZ policies in reducing air pollution and its associated health impacts, suggesting the zone's effects are considerably smaller than previously reported, and that integration with broader policy measures may be necessary to achieve meaningful public health gains.

Women shoulder the majority of water collection labor globally, yet how their water collection and water-related work experiences may change over time or by water source type remains insufficiently understood. We conducted a longitudinal, mixed-methods study in rural Kenya and Honduras to understand how women's experiences collecting water and performing water-related work varied between (a) two time points, (b) improved and unimproved water source types, and (c) water source location. Data were collected in 2023 and 2024 using interviews, observation, GPS-enabled watches, and scales to measure time and distance traveled, water weight and volume carried, and calories expended. 133 women participated in data collection (66 Kenya, 67 Honduras). We compared women's experience data by time point (2023 vs. 2024), source type (improved vs. unimproved), and source location (off-premises vs. on-premises) (t-test, Mann-Whitney U test). We also mapped participants' routes and activities to show which sources were visited, when, and for what activities. In Kenya, mean water collection time, distance, and caloric expenditure were significantly lower and water volume was significantly higher in 2024 when there were unexpected rains compared to 2023 when there was a persistent drought. When comparing source types during the 2023 drought, journeys to improved sources took significantly less time and energy and covered less distance than journeys to unimproved sources. These differences were not observed during the rainy conditions of 2024 when unimproved sources were closer and more accessible. In Honduras, water collection and water work burdens did not differ significantly by time point or source type. We found women with on-premises water access to still expend considerable time and caloric expenditure engaging in water work within their household compounds. Findings from Kenya suggest that water infrastructure improvements can reduce women's water collection burdens, though benefits may depend on and vary by season and source location. Findings from Honduras show that water labor does not end once water is in the household. Rather, substantial time and energy are expended carrying out water-related work even when sources are on premises, suggesting that efforts to assess water labor need to extend beyond collection alone. To meaningfully reduce burdens and ensure improved water sources are utilized during all seasons, initiatives need to consider source location, seasonal variability, and work beyond collection. Evaluations to assess infrastructure impacts on women's labor and well-being are needed and long overdue.

Background: Repeated enteric infections and chronic enteric dysfunction have been associated with undernutrition in children. Interventions that reduce enteric pathogen exposure in young children could thereby improve growth and developmental outcomes. We assessed enteric pathogen prevalence in Bangladeshi infants, the impact of a combined homestead food production and food hygiene intervention on pathogen infections, and associations between pathogen infections, enteric dysfunction markers, and child growth outcomes. Methods: We analyzed panel data from 231 children born between April and December 2018 within the Food and Agricultural Approaches to Reducing Malnutrition (FAARM) cluster-randomized trial in Sylhet, Bangladesh. Stool samples were collected at 0-3, 6-8, and 10-13 months of age and assessed for enteric dysfunction biomarkers (myeloperoxidase, alpha-1 antitrypsin, and neopterin) by ELISA and 14 enteric pathogens by multiplex RT-PCR. Diarrhea prevalence was recorded using 7-day recall. Child length and weight were measured at birth and trial endline. Multilevel regression assessed the intervention effect and quantified associations between pathogen exposure, enteric dysfunction, and growth outcomes. Findings: Enteric pathogen prevalence was high (84%) despite low 7-day diarrhea prevalence (5%), and co-infections were common. There was no intervention effect on the prevalence of enteric pathogens. Shigella spp. and Giardia lamblia were associated with higher myeloperoxidase concentrations, while sapovirus was associated with higher alpha-1 antitrypsin concentrations. Repeated protozoan infections (mainly Giardia lamblia) were associated with lower length-for-age, while repeated viral infections (mainly rotavirus and sapovirus) and Cryptosporidium infections were associated with lower weight-for-height and weight-for-age. There was marginal evidence that bacterial infections were associated with lower length-for-age. Conclusion: The intervention was insufficient to reduce the high burden of enteric pathogens in infants, and subclinical infections were associated with enteric dysfunction and poorer growth outcomes. Comprehensive strategies addressing all key exposure pathways are needed to limit pathogen infections and their consequences for child development.

Food contamination contributes to 40% of childhood diarrhoea cases globally. It occurs when pathogens are transmitted from faecal matter to food through the faecal oral route. Food hygiene can prevent food contamination and improve the microbial quality of weaning foods in domestic settings. However, context specific evidence is needed to identify risk factors associated with food contamination, especially in complex low-income communities. Our study used a modified Hazard Analysis Critical Control Point approach to assess the quality of weaning foods and identify associated risk factors in a low income setting of Lusaka, Zambia. We enrolled 60 caregivers of children aged <1 year who had begun complementary feeding and collected data on household characteristics and food hygiene behaviours using surveys and structured observations. We collected samples of complimentary foods prepared for the child and tested them for Escherichia coli (E. coli) using the IDEXX Colilert-18 method. Multivariable logistic regression was performed to determine risk factors associated with food contamination. Of 59 food samples, 17 (29%) were contaminated with E. coli. Porridge (AOR = 0.04; 95% CI: 0.01, 0.28; p = 0.001) and non-animal source foods (AOR = 0.11; 95% CI: 0.02, 0.69; p = 0.019) were associated with lower odds of contamination compared with animal source foods. Heating of food was also associated with lower odds of contamination but was not significant. Food hygiene behaviours including utensil and surface cleaning were low (17% and 15%, respectively), and handwashing with soap before food preparation was not practiced. Our study identifies the microbiological risk associated with animal source foods and the potential health risk posed to weaning children. Nutrition guidelines should take into consideration this risk as programs promote an increased uptake of animal source foods in child diets.

Background. Current exposure-health models rely on averaged, residential-based environmental exposures, failing to account for human movement. This aggregation can lead to exposure misclassification and biased exposure-response estimates, potentially distorting our understanding of the true health effects of environmental conditions. We developed exposure disaggregation regression models that explicitly account for human movement when linking environmental exposures to health outcomes. Methods. By weighting pixel-level exposures according to distance from home as a simple proxy for human movement, our model linked disaggregated environmental exposures to individual-level health outcomes. Weights were either fixed a priori or derived from a latent distance-decay power parameter learned from the data. We additionally evaluated model performance under a nonlinear exposure-response relationship. Model performance was assessed across multiple sample sizes (N = 1,114; 50,000; and 100,000). A simulation study examined parameter recovery using bias, empirical standard error (EmpSE), and credible interval coverage. As a case study, Demographic and Health Surveys (DHS) data from Albania were used to link acute respiratory infection (ARI) outcomes among children under five to pixel-level NDVI within a 3 km buffer around DHS cluster centroids, and the proposed models were applied to these data. Results. Across all models (fixed-weight, learned-weight, and restricted cubic spline models), parameter recovery improved with increasing sample size. At N = 1,114, estimates were biased and imprecise, with incorrect effect direction for exposure-response parameters (e.g., learned-weight {beta}1 bias = - 0.79; EmpSE = 2.61; coverage = 0.88). In contrast, the models accurately recovered parameters at larger sample sizes, including the latent distance-decay parameter (bias = - 0.02; EmpSE = 0.15; coverage = 0.95 at N = 100,000), demonstrating their ability to reliably learn movement-based exposure weights when sufficient data were available. Conclusion. Instead of relying on arbitrarily-sized buffers, this statistical framework provides a novel method for studying environmental exposure-health relationships whilst accounting for human movement. With sufficiently large sample sizes, it can accurately estimate the influence of disaggregated environmental exposures on individual-level health and help address exposure misclassification arising from residential-only metrics. This methodological framework remains scalable, interpretable, and adaptable to other exposures and outcomes, offering a foundation for future work that integrates richer mobility-informed exposure-health research.

Mass gatherings pose significant public health risks by facilitating the spread of infectious diseases. While wastewater-based surveillance (WBS) has been widely used to monitor pathogens in high-income settings, its use as a practical, multi-pathogen surveillance tool during mass gatherings in low- and middle-income countries remains limited. This study aimed to assess the operational feasibility, epidemiological significance, and public health utility of multi-pathogen WBS during the African Nations Championship (CHAN) football tournament in Uganda. Wastewater surveillance was conducted at Mandela National Stadium during eight match days in August 2025. Moore swabs were deployed at 38 manholes receiving wastewater from different toilet facilities across the stadium to capture representative wastewater samples. Samples were processed using Nanotrap(R) microbiome virus particles to concentrate pathogens, followed by nucleic acid extraction. Samples were analyzed for multiple enteric and respiratory pathogens, including Mpox, using quantitative PCR (qPCR). Descriptive analyses were performed to characterize pathogen detection patterns, positivity rates, and temporal distribution across surveillance sites. A total of 304 wastewater samples were collected and analyzed, of which 259 (85.2%) tested positive for at least one pathogen. Multiple pathogens were consistently detected across sampling days, with enteric pathogens predominating, particularly Shigella spp. (53.6%), Rotavirus A (35.9%) and Enterovirus (32.2%). The mpox virus was also detected in a notable proportion of samples (28.6%) across several sampling days. Respiratory pathogens, including SARS-CoV-2 (11.8%) and Influenza B (8.2%), were identified intermittently at lower frequencies. Pathogen diversity varied over time, with up to eight pathogens detected on a single day, and co-detection of multiple pathogens observed in the majority of positive samples. Cq value distributions further demonstrated variability in detected signal patterns across pathogens. Surveillance findings informed real-time public health interventions, including sanitation reinforcement, intensified hygiene promotion, environmental disinfection, and targeted risk communication, strengthened syndromic surveillance with on-site triage, and targeted environmental health assessments of food handling and wastewater infrastructure. These findings demonstrate the operational feasibility and public health utility of integrating multi-pathogen wastewater-based surveillance into mass-gathering preparedness and response frameworks in low-resource settings. By capturing diverse pathogen signals and informing targeted interventions during the CHAN football tournament, WBS can provide actionable population-level insights that can support outbreak preparedness and response. Scaling WBS within national preparedness systems could strengthen epidemic intelligence, enhance early warning capacity, and support data-driven public health decision-making during future mass gatherings and emerging infectious disease threats.