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.

Background: The proportion of births occurring at healthcare facilities is rising globally, yet the birthing environment in healthcare facilities in low-income settings is often contaminated with bacterial pathogens, including antibiotic-resistant pathogens, that can lead to serious infections for newborns and their mothers. There is a need for effective strategies to reduce environmental contamination in healthcare facilities to reduce infection risks among facility-born neonates and their mothers. Methods: We designed the CLEAN (ChLorine to reduce Enteric and Antibiotic resistant infections in Neonates) cluster randomized controlled trial in western Kenya to evaluate the impact of a multi-component chlorination intervention on environmental contamination and maternal and neonatal infection risks. Thirty-six medium-sized public health facilities will be randomized in a 1:1 allocation ratio to receive a passive chlorination technology for water supply treatment paired with a reliable supply of chlorine-based disinfectant or status quo. Up to 22,500 mothers-neonate dyads will be enrolled and followed from birth through 28 days to collect symptoms of infection and mortality, with a subset of mother-neonate dyads selected for rectal swab collection to measure rectal colonization with sepsis-associated bacterial species. Environmental samples will be collected to measure bacterial pathogens on staff hands, high-touch surfaces, and in water supply. The primary objectives of the study are to evaluate the impact of the intervention on the following outcomes: (1) rectal carriage of bacterial pathogens one week post-birth among facility-born neonates and their mothers, (2) cumulative incidence in the first 7 days post-birth of possible serious bacterial infection among facility-born neonates, and (3) cumulative incidence in the first 7 days post-birth of symptoms of possible maternal sepsis. Discussion: This study will generate evidence on the effectiveness of a novel chlorination intervention to reduce healthcare associated infections, including antibiotic resistant infections, and improve maternal and neonatal survival. Trial registration: Clinical Trials NCT06824350. Registered 7 February 2025, https://clinicaltrials.gov/study/NCT06824350

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.

Background. Safely managed drinking-water monitoring under Sustainable Development Goal target 6.1 uses source-water quality, yet Escherichia coli is common in household drinking water in Bangladesh despite near-universal improved sources. We compared source and household point-of-use (POU) E. coli detection within households and estimated how the safely managed estimate changes if POU replaces source E. coli. Methods. Cross-sectional secondary analysis of the Bangladesh MICS 2025 water-quality subsample (February-June 2025; detection >=1 colony-forming unit/100 mL). We classified 5,944 households with readable paired results into four joint patterns and, exploratorily, examined POU detection among negative-source households and two-week diarrhoea in children under five with survey-weighted modified Poisson models. Results. E. coli was detected in 47.4% of source and 84.8% of POU samples; only 12.7% of households were negative at both. Among negative-source households, 75.8% had E. coli in household water, versus 94.7% with a detected source, persisting (33.3%) even direct from the source. The JMP-aligned safely managed estimate was 42.5% (95% CI 40.8-44.1); substituting POU for source E. coli gave 12.6% (11.4-13.8), not an SDG indicator estimate. The diarrhoea prevalence ratio for POU detection (1.04, 0.59-1.86) was too imprecise to interpret. In exploratory spatial analysis, POU detection clustered geographically (Moran's I 0.16 cluster level, 0.31 district level, both p<0.001) and was independently associated with lower elevation (odds ratio 0.62, 0.56-0.70) and longer travel time to healthcare (1.65, 1.29-2.12); five districts had complete detection among 84-94 households tested. Conclusions. Source and POU classifications differed substantially; the survey cannot show where or when contamination occurred. Contamination was spatially clustered, arguing against pure noise and pointing to districts for follow-up. The findings support evaluating standardised POU sampling as a complement to source-based monitoring, with targeted follow-up and cross-season, cross-country replication.

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.

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: Chronic arsenic exposure in drinking water causes skin lesions and cancers and raises infant, cardiovascular and all-cause mortality in Bangladesh. National surveys tested source water in 2012-13, 2019 and 2025 with different kits, so the trend is uncertain. Objectives: We estimated how arsenic in source water changed after laboratory adjustment of 2012-13 readings, and how many people remained exposed. We also assessed whether districts high in earlier surveys held most people exposed in 2025. Methods: We analysed 11,624 households in three Multiple Indicator Cluster Surveys. We counted arsenic strictly above 10 and 50 parts per billion (ppb). Results: Estimates reproduced published 2019 and 2025 tables. After laboratory adjustment of 2012-13, the share above 10 ppb fell from 24.0% to 14.4% (adjusted ratio 0.61, sampling 95% CI 0.55 to 0.67; 0.69 with interview month). Above 50 ppb it fell from 10.9% to 8.6% (0.80, 0.69 to 0.93; 0.93 with month). Most of the fall at 10 ppb occurred within source types. Without false positives, it would vanish only if later kits detected 61% of sources above 10 ppb. About 26 million people used such water in 2025 (kit scenarios 23 to 32 million). The 25 districts high in 2012-13 and 2019 held 39% of the population but 72% of those exposed (bootstrap 95% interval 60 to 76). Clustering was evident, but no district was a significant hotspot. Conclusions: Arsenic above 10 ppb was lower in 2025 than in 2012-13, but the size of the fall depends on unverified later kits. Change at 50 ppb and since 2019 was unclear after month adjustment. One household in seven exceeded the WHO guideline in 2025. Districts found high earlier held most exposed people, supporting prioritised well testing there alongside broader surveillance. Future surveys need one kit with a laboratory cross-check.

Introduction: Pesticide exposure has been associated with poorer mental health, yet little is known about whether seasonal fluctuations in agricultural pesticide use are associated with cyclical changes in mood among people living in agricultural communities. We evaluated associations between 10 peak and off-peak pesticide spray seasons and ecological momentary assessment (EMA)-derived mood in a floricultural region in Ecuador. Methods: 496 participants completed repeated EMA surveys across 10 assessment administrations over 2.5 years (2022-2024), including one single-assessment administration and nine 10-day bursts (Nobservations=14,332). Mood outcomes included negative affect (sadness, anxiety, stress, anger, tiredness, difficulty concentrating; overall mean=2.79, Standard Deviation [SD]=1.32), positive affect (happiness, motivation; overall mean=4.21, SD=1.60), and behavioral dysregulation (aggression and impulsivity, overall mean=1.86, SD=1.29). Generalized linear mixed models estimated pooled, between-person and within-person associations between peak pesticide spray seasons and mood, adjusting for demographic and longitudinal factors Effect modification by sex, floricultural occupation, and cohabitation with a floricultural worker was assessed. Results: Peak spray seasons were associated with higher negative affect ({beta}=0.11 [0.06, 0.16]) and behavioral dysregulation ({beta}=0.10 [0.05, 0.15]) but not positive affect ({beta}=0.01 [-0.05, 0.07]). Associations were driven by within-person changes. Sex modified associations with negative affect, which were stronger in males than females. Floricultural occupation modified associations, with poorer mood, greater behavioral dysregulation and lower positive affect among floricultural workers than non-workers. Discussion: Peak pesticide spray seasons were associated with worsening of negative affect and behavioral dysregulation. EMA may provide a sensitive approach for detecting short-term neurobehavioral changes associated with seasonal pesticide exposure.

Background: In coastal Bangladesh, saline drinking water has been linked to raised blood pressure. The 2025 Multiple Indicator Cluster Survey (MICS) measured electrical conductivity (EC), a salinity indicator, in source water, but its report gave no population counts or district estimates. Objectives: To estimate how many people live in households whose tested source has high EC, and to describe patterns by place, household characteristics, source type and arsenic. Methods. EC was measured in source water of 6,040 households in 64 districts, February to June. In 14.5% of households the tested source was not the main drinking-water source. Primary outcomes were EC above 1,500 and 3,000 microsiemen/cm, survey risk classes that are not health-based standards. Estimates were survey weighted; comparisons were observational. Results: EC exceeded 1,500 microsiemen/cm in 5.3% of households (95% CI 4.7 to 5.9), about 9.0 million people, including 1.8 million above 3,000 microsiemen/cm. Coastal-zone districts held 26% of households but 70% of those above 1,500 microsiemen/cm. Shares varied little by wealth or in households with young children or pregnant women. Nationally, deep tube wells more often had high EC because most are coastal. In the coastal zone, deep and shallow wells had similar shares (16.1% and 17.9%). After district adjustment, EC was about 18% lower in deep wells (geometric mean ratio 0.82, 0.73 to 0.92). Within upazilas (restricted sample) it was 0.93 (0.80 to 1.07). Arsenic above 10 ppb was more common where EC was high, but this link weakened after district adjustment. Conclusions: Millions of people live in households whose tested source has high EC, mostly in coastal and south-central districts. Deep wells had modestly lower EC after geographic adjustment, but the difference shrank within upazilas and depended on the handling of implausibly low readings. The findings support measuring EC alongside arsenic, with documented meter calibration.

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.

Abstract Background Air pollution contributes substantially to morbidity and mortality in low-income countries, where reliance on solid fuels leads to high levels of household exposure. Colonisation of the upper respiratory tract by Streptococcus pneumoniae is a prerequisite for pneumococcal disease, and inhaled air pollutants may influence colonisation through impaired mucociliary clearance. Therefore, we investigated the association between S. pneumoniae colonisation and personal exposure to particulate matter (PM2.5) and carbon monoxide (CO) as well as temperature and relative humidity in older children in The Gambia. Methods We conducted a prospective study of 134 children aged 5-14 years across eight visits in rural Gambia. Personal 24-hour PM2.5, CO, temperature and relative humidity exposures were measured using personal monitors. Concurrently, combined nasopharyngeal/oropharyngeal swabs were collected at each visit, and S. pneumoniae colonisation was determined by microbiological culture. Mixed-effects logistic regression models were used to examine associations between environmental exposures and colonisation. Exposures were additionally decomposed into between-child and within-child components. Models were adjusted for age, season, and household income tertile. Results A total of 554 child visits with paired exposure and microbiological data were analysed. Overall, 24-hour geometric mean PM2.5 and CO were 12.6 {micro}g/m3 (95% CI 12.2-13.1) and 0.16 ppm (95% CI 0.14-0.19) respectively and overall S. pneumoniae colonisation prevalence was 39.7%. In conventional models, PM2.5, CO, temperature, and relative humidity were not significantly associated with S. pneumoniae colonisation after adjustment for confounders. In the within-between decomposition analysis, higher between-child temperature exposure was consistently associated with lower odds of colonisation (mutually adjusted model: OR 0.74, 95% CI 0.56-0.98; p = 0.034). Relative humidity showed an inverse within-child association in crude analysis (OR 0.70, 95% CI 0.52-0.93; p = 0.013), which attenuated after adjustment for season and other confounders. No associations were observed for PM2.5 or CO exposures. Conclusion At the exposure levels observed in this cohort of older children, PM2.5 and CO exposures were not independently associated with S. pneumoniae colonisation. The pattern observed for temperature suggests that longer-term temperature conditions may be more relevant to pneumococcal colonisation than short-term exposure variation in this setting.

Coccidioidomycosis (Valley fever) is a soilborne mycosis endemic to the US Southwest whose incidence has increased markedly in recent decades. Environmental conditions are thought to influence the soil-dwelling lifecycle of Coccidioides; however, most prior studies have relied on above-ground meteorological conditions - primarily precipitation and air temperature (AT) - with few examining subsurface soil moisture (SM) and soil temperature (ST), which may more directly influence the fungal lifecycle. No study of coccidioidomycosis, or any other environment-sensitive soilborne mycosis, has examined how deeper-layer soil conditions relate to disease incidence, despite the prevailing soil-sterilisation hypothesis implicating deeper soil as a potential fungal refugium. Furthermore, nonlinear exposure-lag-response relationships for key dust-dispersion exposures - including PM10, a potential proxy for airborne spore concentration, and wind speed - remain uncharacterised. We aimed to estimate and compare the associations between coccidioidomycosis incidence and environmental exposures across multiple above- and below-ground layers, and to evaluate their independent and combined predictive performance. This ecological time-series study analysed 185,486 reported cases of coccidioidomycosis in Arizona's hyperendemic tri-county region (Maricopa, Pima, and Pinal) during 1997-2024. We developed a mechanism-informed multilayer environmental framework comprising one dust-dispersion layer (PM10, wind speed) and four soil-climate layers - meteorological (precipitation, AT), topsoil (0-10 cm), midsoil (10-40 cm), and deepsoil (40-100 cm) SM and ST. We fitted distributed lag non-linear models (DLNMs) with season-specific interaction terms to estimate exposure-lag-response associations between each environmental layer and coccidioidomycosis incidence. We then developed a two-stage stacked ensemble machine learning framework to assess each layer's independent predictive performance (stage 1) and integrate them into a unified forecast (stage 2), which was evaluated using a strictly held-out test period. At concurrent lags (1-3 months prior to reporting), coccidioidomycosis incidence was primarily associated with dustier, windier, and drier conditions, cooler air temperatures, and warmer topsoil. For each IQR increase, PM10 showed the most consistent concurrent associations, with significant positive incidence rate ratios (IRRs) across all four incidence seasons at lags 1-2 (ranging from 1.04 [95% CI 1.00-1.08] to 1.37 [1.26-1.48]). Across lags 1-36 months, all four soil-climate layers exhibited nonlinear, non-monotonic, and season-dependent associations with coccidioidomycosis incidence, characterised by alternating wet-dry and cool-warm oscillations. Topsoil displayed the most frequent significant associations, with moisture-temperature signals attenuating progressively from topsoil through midsoil to deepsoil. A depth-dependent lag structure was observed for both moisture and temperature, in which significant positive IRRs emerged at progressively shorter lags with increasing soil depth, accompanied by vertical divergence across depths at the same lag windows. For example, for fall incidence, positive moisture IRRs appeared at precipitation lag 15 (1.10 [1.00-1.21]), topsoil SM lag 9 (1.22 [1.15-1.30]), midsoil SM lags 8-9 (up to 1.23 [1.11-1.37]), and deepsoil SM lags 4-5 (up to 1.08 [1.01-1.16]); at these same lags, deepsoil SM was positively associated with incidence whereas topsoil SM and precipitation remained negatively associated. During the held-out test period (2021-2024), the multilayer ensemble generally captured seasonal and interannual variation well, including the timing and approximate magnitude of most peaks, outperforming all single-layer models. Although individual layers had slightly lower test RMSEs, their test gap ratios were substantially higher (0.27-0.67 vs 0.00), indicating that the ensemble generalised far more reliably. All five environmental layers contributed to the final ensemble forecast; the dust-dispersion and topsoil layers received the highest importance, with PM10 ranked as the most important predictor group. The best-performing of four pipeline configurations relied solely on environmental inputs available within one week, enabling the model to function as a near-real-time nowcast. This study provides the first evidence linking multilayer environmental exposures to coccidioidomycosis incidence across both temporal and vertical dimensions, offering new quantitative support for the prevailing soil-sterilisation and grow-and-blow hypotheses and demonstrating that a multilayer framework could improve both mechanistic understanding and predictive performance. The framework could be generalised to other endemic settings and readily extended with new data and methods to inform surveillance and public health preparedness. These findings support incorporating multilayer lagged environmental exposures into both effect estimation and forecasting systems to better prepare endemic regions for anticipated warming, drying, and increasingly variable climatic conditions.

Bangladesh's agricultural sector remains heavily dependent on pesticides and chemical inputs, yet limited attention has been paid to how farmers' knowledge of occupational health and environmental sustainability translates into actual practice across the full agricultural value chain. This study aimed to assess the knowledge and practices of farmers in Pabna District, Bangladesh, regarding occupational health, pesticide handling, environmentally sustainable farming, and market sanitation. A cross-sectional survey was conducted among 301 farmers in 2024 using a structured questionnaire covering socio-demographic characteristics, sustainable farming knowledge and adoption, soil testing and organic farming practices, pesticide handling and occupational health and safety behaviours, post-harvest waste management, and market sanitation conditions. Data were analysed using descriptive statistics. The majority of respondents were male (87.04%) and had no formal education (63.46%). Although most farmers reported knowledge of environmentally sustainable farming practices (97.70%) and pesticide label instructions (98.00%), corresponding safety practices were poor: only 10.63% reported wearing any personal protective equipment and 1.33% reported using a mask during pesticide application. Eye irritation was the most commonly self-reported health symptom following pesticide exposure (92.69%). Market sanitation infrastructure was similarly inadequate, with 89.00% of respondents reporting an absence of sanitary toilets. These findings indicate a consistent gap between farmers' knowledge and their actual practices across multiple domains of the agri-food system. Strengthening extension services, delivering practical hands-on occupational safety training, and investing in market sanitation infrastructure are recommended to close this gap and support safer, more sustainable farming practices in Bangladesh.

Objective: Environmental pollutants are increasingly recognized as potential risk factors for metabolic dysfunction-associated steatotic liver disease (MASLD), yet the effects of mixed exposures and underlying mechanisms remain unclear. We evaluated associations between environmental chemical mixtures and MASLD and the mediating role of inflammation-related biomarkers. Methods: We analyzed 60 environmental chemicals across six categories among 39,061 U.S. adults from the National Health and Nutrition Examination Survey (NHANES) 1999-2020. Principal Component Pursuit with Principal Component Analysis (PCP-PCA) identified latent exposure patterns. MASLD was identified using multisociety Delphi consensus criteria and the Hepatic Steatosis Index (HSI [&ge;] 36). Logistic regression, restricted cubic spline models, and mediation analysis were applied. Results: PCP-PCA generated 5-17 dimensions per chemical category, with first-dimension variance contributions ranging from 30.70% to 98.88%. Six dimensions from four categories were retained, with phthalate esters (PAEs) and organophosphate flame retardants (OPFRs) showing the most consistent associations with MASLD. PAEs Dim.1, explaining 90.71% of variance, showed a significant non-linear dose-response association (P-nonlinear = 0.0001). Significant associations were identified for mono-isobutyl phthalate (MiBP; OR 1.12, 95% CI 1.07-1.19), mono(carboxyoctyl) phthalate (MCOP; OR 1.08, 95% CI 1.02-1.14), mono(carboxynonyl) phthalate (MCNP; OR 1.12, 95% CI 1.03-1.21), and bis(1,3-dichloro-2-propyl) phosphate (BDCP; OR 1.15, 95% CI 1.08-1.23). C-reactive protein (CRP) and red cell distribution width (RDW) were the primary mediators, accounting for 32.42% and 19.62% of the MiBP-MASLD association, respectively (both p < 0.0001). Conclusion: Environmental co-exposure, particularly to PAEs and OPFRs, was associated with higher MASLD risk, with systemic inflammation potentially contributing to these associations.

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.

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.

Zoonotic spillover and early human-to-human transmission of emerging viruses are often missed by clinical surveillance. Wastewater surveillance (WS) offers low-cost complementary pathogen detection, but its value for emerging viruses remains uncertain. We reviewed evidence of viral shedding in human waste and combined shedding data, detection models and simulated transmission dynamics into a quantitative framework to identify for which types of emerging viruses WS could add most value. Simulations showed that WS improved probability or speed of outbreak detection for viruses shedding >1/100 to >10 times as much as SARS-CoV-2, depending on probability of clinical symptoms and diagnosis. Value added was highest for transmission scenarios with temporally concentrated infections resulting in spikes in daily shedders. Characteristics of SARS-CoV-2, Mpox, Influenza A, Lassa, and Zaire Ebola viruses appear more favourable for WS than others e.g. chikungunya virus. We anticipate this framework can support more targeted, evidence-based application of WS to emerging threats.