International Journal of Hygiene and Environmental Health
The International Journal of Hygiene
The Heat That Kills Quietly: Urban Heat Islands and the Hidden Rise of Cardiovascular Mortality
Abstract Urban heat islands (UHI) intensify temperature exposure in densely built environments, amplifying health risks during extreme heat events. This population-based environmental epidemiology study assessed the relationship between UHI exposure and cardiovascular mortality across 12 metropolitan regions between 2020 and 2024. A total of 148,320 deaths were analyzed alongside high-resolution temperature mapping and land-surface heat indices. During heatwave periods, mortality increased by 13.9% (95% CI 11.8–16.2; p<0.001) in high-UHI zones compared with low-exposure areas. Night-time temperature elevation was a critical factor, with each +2°C increase associated with a 7.4% rise in cardiovascular deaths. Individuals aged ≥70 years showed the highest vulnerability (RR 1.21), while socioeconomically deprived neighborhoods experienced 1.8-fold higher mortality risk. Hospital admissions for cardiac events increased by 19.6%, and stroke-related mortality rose by 14.2% during peak heat exposure. Urban areas with limited green space (<15% coverage) demonstrated significantly higher risk compared with greener districts. A predictive heat-health model combining temperature, humidity, and land-use variables achieved AUC 0.85, identifying high-risk mortality days with strong accuracy. These findings highlight urban heat islands as a major environmental determinant of cardiovascular mortality. Expanding green infrastructure, improving urban design, and strengthening early warning systems are critical strategies for reducing heat-related health risks in cities.
Urban Heat Island, Cardiovascular Mortality, Climate Change, Environmental Health, Heatwave
Copyright (c) 2026 International Journal of Hygiene and Environmental Health
Climate-Related Environmental Exposures and Ocular Surface Disorders: A Systematic Review
Background: The ocular surface is constantly exposed to environmental stressors. Climate related factors such as temperature, humidity, ultraviolet radiation, air pollution, dust storms, wildfire smoke, altitude, and extreme weather can disrupt tear film stability and contribute to ocular surface disease. Although previous reviews have examined broader ocular effects of climate change, few have focused specifically on the ocular surface. Objective: To systematically review evidence on the association between climate related environmental exposures and ocular surface disorders, including dry eye disease, conjunctivitis, keratitis, and pterygium, and to summarize mechanisms, vulnerable groups, and adaptation strategies. Methods: PubMed, Web of Science, and Google Scholar were searched for studies published up to March 2026. Eligible studies included observational, experimental human exposure, and mechanistic designs assessing temperature, humidity, UV exposure, air pollutants, dust storms, wildfire smoke, altitude, or extreme weather in relation to ocular surface outcomes. Results: Thirty eight studies were included. Low humidity and low temperature were consistently associated with worsening dry eye symptoms and signs. Air pollutants, especially particulate matter, nitrogen dioxide, and ozone, were linked to increased outpatient visits for dry eye and conjunctivitis. Wildfire smoke caused acute ocular surface inflammation. Dust storms and wind increased conjunctivitis risk. Higher temperature and UV exposure were associated with pterygium, while high altitude was linked to markedly higher prevalence. Keratitis showed seasonal variation. Conclusions: Climate related exposures significantly affect ocular surface health. Protective measures and further longitudinal research are needed to reduce climate related ocular morbidity.
Climate change, ocular surface disorders, dry eye disease, air pollution, ultraviolet radiation, pterygium, conjunctivitis, keratitis
Microplastics and Nanoplastics in Eye Health: Ocular Exposure, Toxicity, and Clinical Implications
Microplastics (MPs) and nanoplastics (NPs) are increasingly recognized as pervasive environmental contaminants with potential implications for human health, but their relevance to ocular tissues remains incompletely understood. This review synthesizes current evidence on ocular exposure pathways, detection of plastic particles in ophthalmic products and human ocular samples, and their potential toxic effects on the ocular surface and posterior segment. A structured literature search was conducted across PubMed, Scopus, Web of Science, and Google Scholar from database inception to 23 March 2026. Because of substantial heterogeneity in study design, particle characteristics, analytical methods, and reported outcomes, the findings were synthesized narratively rather than quantitatively. Available evidence suggests that ocular exposure may occur through airborne deposition, contaminated ophthalmic formulations, contact lens-related plastic debris, periocular cosmetic products, waterborne contact, surgical settings, and systemic translocation after inhalation or ingestion. MPs have been detected in tear fluid, meibum, pterygium tissue, cataract surgery-related samples, commercial eye drops, vitreous samples, and post-mortem human retinal tissue. Experimental studies indicate that these particles may induce oxidative stress, inflammation, mitochondrial dysfunction, epithelial injury, goblet cell loss, tear film instability, lacrimal and meibomian gland dysfunction, retinal pigment epithelial damage, microvascular impairment, and increased vascular permeability. However, current human evidence is limited, largely observational, and subject to major methodological challenges, particularly contamination during sampling and variability in particle detection and identification techniques. Although the available literature supports biological plausibility for ocular toxicity, definitive causal relationships, real-world exposure thresholds, and the clinical significance of ocular plastic burden remain uncertain. Further standardized, longitudinal, and mechanistic studies are needed to determine the true impact of MPs and NPs on eye health.
microplastics; nanoplastics; ocular surface; retina; tear film; eye drops
Ambient Air Pollution and Dry Eye Disease: A Systematic Review of Epidemiological and Clinical Evidence
Background: Dry eye disease is a common multifactorial disorder of the ocular surface characterized by tear film instability, hyperosmolarity, inflammation, and visual discomfort. In recent years, growing attention has focused on the role of environmental exposures, particularly ambient air pollution and adverse climatic conditions, in the onset and progression of dry eye disease. This systematic review aimed to synthesize current epidemiological and clinical evidence on the association between ambient air pollution, meteorological factors, and dry eye disease. Methods: A systematic search of PubMed, Web of Science, and Google Scholar was conducted up to 23 March 2026. Eligible studies included original human investigations that assessed ambient air pollutants or environmental stressors such as particulate matter, ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, humidity, temperature, wind, air conditioning, or greenness in relation to dry eye disease symptoms, diagnosis, or objective ocular surface parameters. Data were extracted on study design, setting, population, exposures, outcomes, and main findings. Due to heterogeneity in methodology and outcome definitions, findings were synthesized narratively. Results: Thirty epidemiological studies and several mechanistic investigations were included. The most consistent associations were observed for particulate matter, ozone, nitrogen dioxide, and low relative humidity. These exposures were linked to increased dry eye symptoms, higher outpatient attendance, reduced tear breakup time, greater tear osmolarity, reduced tear secretion, and increased corneal staining. Sulfur dioxide and carbon monoxide showed less consistent associations across settings. Indoor and occupational exposures, including air conditioning, traffic-related pollution, and dust, also appeared to worsen ocular surface health. Green space exposure showed a potential protective effect in some studies. Conclusion: Ambient air pollution and adverse environmental conditions appear to contribute meaningfully to the development and exacerbation of dry eye disease. The strongest evidence implicates particulate pollutants, ozone, nitrogen dioxide, and low humidity. These findings support the need to integrate environmental exposure history into dry eye assessment and to consider air quality and microclimate improvement as part of broader prevention strategies.
dry eye disease, air pollution, particulate matter, humidity, ocular surface, environmental exposure
Waste That Spreads Disease: Solid Waste Mismanagement and Vector-Borne Outbreak Risk
Abstract Uncontrolled solid waste accumulation creates breeding habitats for disease vectors and contributes to repeated outbreaks of mosquito-borne illness in densely populated communities. This environmental outbreak study evaluated the association between waste mismanagement and vector-borne disease risk across 22 high-density urban sectors from 2021 to 2024. The analysis included 1,964 reported vector-borne disease cases, entomological surveys from 312 waste accumulation sites, and environmental audits of local waste disposal practices. Neighborhoods with irregular waste collection schedules had 2.7 times higher vector density indices than areas with routine collection (p<0.001). Open waste piles containing plastic containers, tires, and stagnant water supported Aedes breeding in 48.9% of surveyed sites. The incidence of dengue-like illness reached 22.6 cases per 10,000 population in high-waste neighborhoods compared with 9.4 per 10,000 in low-waste zones. Presence of uncollected waste within 50 meters of households increased outbreak risk by 2.3-fold (OR 2.3, 95% CI 1.8–2.9; p<0.001). Larval positivity rates were 41.7% in unmanaged sites versus 17.5% in managed environments. Children and young adults accounted for 56.1% of outbreak-related cases, while 11.2% of patients required hospital observation. Areas with poor drainage and intermittent water supply showed the highest co-occurrence of breeding sites and transmission clusters. After community clean-up campaigns, improved waste collection, and vector control spraying, vector density fell by 37.4%, and new case incidence decreased by 29.6% over a 4-month surveillance period. These findings indicate that solid waste mismanagement is not only an environmental problem but also a major outbreak amplifier. Integrating municipal waste control with vector surveillance and hygiene promotion may substantially reduce mosquito-borne disease transmission in urban settings.
Solid waste, vector-borne disease, dengue, environmental hygiene, outbreak risk
Invisible Heat, Visible Mortality: Quantifying the Delayed Cardiometabolic Impact of Urban Heat Waves in Southern Europe
Background: Extreme heat events are increasing in frequency and intensity across Southern Europe. While acute heat-related mortality is recognized, delayed cardiometabolic consequences remain underexplored. This study quantified short- and medium-term mortality and hospitalization risks associated with urban heat waves. Methods: We conducted a population-based time-series study across five major Greek cities between 2010 and 2024. Heat waves were defined as ≥3 consecutive days above the 95th percentile of historical temperature distribution. Distributed lag non-linear models assessed associations between temperature exposure and cardiometabolic mortality and hospital admissions over 21 lag days. Models adjusted for air pollution, humidity, seasonal trends, and long-term temporal variation. Results: A total of 14,732 cardiometabolic deaths were recorded during the study period. Heat waves were associated with a 17.8 percent increase in cardiometabolic mortality (relative risk 1.18; 95 percent confidence interval 1.12 to 1.24; p < 0.001) and a 12.4 percent increase in hospital admissions (relative risk 1.12; 95 percent confidence interval 1.07 to 1.18; p < 0.001). Peak risk occurred at lag days 2 to 4, but elevated risk persisted up to 14 days. Individuals aged ≥75 years exhibited the highest vulnerability (relative risk 1.29; 95 percent confidence interval 1.19 to 1.41). Incorporating heat exposure metrics improved predictive accuracy of mortality models (AUC increase from 0.74 to 0.83). Conclusion: Urban heat waves exert substantial delayed cardiometabolic impacts beyond immediate exposure periods. These findings underscore the urgency of adaptive public health strategies, early warning systems, and targeted protection of vulnerable populations in the context of accelerating climate change. Background: Extreme heat events are increasing in frequency and intensity across Southern Europe. While acute heat-related mortality is recognized, delayed cardiometabolic consequences remain underexplored. This study quantified short- and medium-term mortality and hospitalization risks associated with urban heat waves. Methods: We conducted a population-based time-series study across five major Greek cities between 2010 and 2024. Heat waves were defined as ≥3 consecutive days above the 95th percentile of historical temperature distribution. Distributed lag non-linear models assessed associations between temperature exposure and cardiometabolic mortality and hospital admissions over 21 lag days. Models adjusted for air pollution, humidity, seasonal trends, and long-term temporal variation. Results: A total of 14,732 cardiometabolic deaths were recorded during the study period. Heat waves were associated with a 17.8 percent increase in cardiometabolic mortality (relative risk 1.18; 95 percent confidence interval 1.12 to 1.24; p < 0.001) and a 12.4 percent increase in hospital admissions (relative risk 1.12; 95 percent confidence interval 1.07 to 1.18; p < 0.001). Peak risk occurred at lag days 2 to 4, but elevated risk persisted up to 14 days. Individuals aged ≥75 years exhibited the highest vulnerability (relative risk 1.29; 95 percent confidence interval 1.19 to 1.41). Incorporating heat exposure metrics improved predictive accuracy of mortality models (AUC increase from 0.74 to 0.83). Conclusion: Urban heat waves exert substantial delayed cardiometabolic impacts beyond immediate exposure periods. These findings underscore the urgency of adaptive public health strategies, early warning systems, and targeted protection of vulnerable populations in the context of accelerating climate change.
Heat waves, climate change, cardiometabolic mortality, environmental epidemiology, public health adaptation
Water That Carries Disease: Hygiene Failure and the Hidden Drivers of Diarrheal Outbreaks in Urban Settlements
Diarrheal diseases continue to impose a substantial public health burden in densely populated urban settlements, where poor sanitation, unsafe water storage, and inconsistent hygiene practices create ideal conditions for rapid outbreak propagation. This population-based outbreak study assessed the contribution of environmental hygiene failures to diarrheal disease transmission across 18 urban districts between January 2021 and December 2024. A total of 2,860 laboratory-supported or clinically confirmed diarrheal cases were identified, with a cumulative incidence of 17.4 cases per 1,000 population during outbreak periods. Environmental investigation included 612 household water samples, 428 sanitation site assessments, and structured interviews from 1,140 households. Interrupted piped water supply was documented in 63.8% of affected neighborhoods and was associated with a 2.6-fold higher outbreak risk (RR 2.6, 95% CI 2.1–3.2; p<0.001). Unsafe household water storage practices, including uncovered containers and infrequent disinfection, were observed in 38.4% of affected households, while fecal contamination with E. coli above recommended limits was found in 42.7% of tested water samples. Households lacking functional handwashing stations had 2.1 times higher odds of infection (OR 2.1, p<0.001), and shared sanitation facilities serving more than five households increased transmission risk by 74.0%. Children under five accounted for 31.6% of total cases, and hospitalization was required in 12.8% of patients. Districts with poor drainage and solid waste accumulation had a 2.9-fold higher likelihood of recurrent outbreak clusters. Following the implementation of water chlorination, hand hygiene education, and household sanitation campaigns, incidence declined by 31.2% within 6 months, while repeat cluster events dropped from 11 to 5 outbreaks. These findings demonstrate that diarrheal outbreaks in urban settlements are strongly shaped by environmental hygiene breakdowns. Strengthening water quality monitoring, safe storage, and community hygiene interventions may substantially reduce outbreak frequency and disease severity.
Diarrheal disease, water hygiene, sanitation, outbreak investigation, environmental health
Lifestyle Behaviors and Weight Regain after Bariatric Surgery in Saudi Arabia: Systematic Review of Observational Studies
Doi : https://doi.org/10.5281/zenodo.19145179 Weight regain following bariatric surgery is a common challenge that can diminish the long-term health benefits of the procedure. This systematic review examined observational evidence on how postoperative lifestyle behaviors such as physical activity, sedentary time, smoking, and dietary habits are associated with weight recurrence. Guided by PRISMA standards, we searched six electronic databases from their inception until December 2025. Sixteen studies met the inclusion criteria, comprising international observational research and studies drawn from Saudi populations. The evidence consisted mainly of cross-sectional studies, supplemented by a smaller set of prospective cohort analyses. Definitions of weight regain varied widely across studies, ranging from absolute weight gained after the lowest postoperative weight to percentages of weight or excess weight regained. Across the literature, several behaviors were consistently linked to weight regain: insufficient physical activity, high sedentary time, tobacco and waterpipe use, disordered eating patterns (such as grazing, emotional eating, and binge eating), poor diet quality, and inadequate postoperative follow-up. Data from Saudi Arabia offered relevant regional insights, indicating that lifestyle and dietary patterns are closely connected to weight outcomes after surgery, though results were not uniform across different settings. Overall, the evidence suggests that modifiable lifestyle behaviors may significantly influence the likelihood of postoperative weight regain. However, causal conclusions are limited by considerable variation in how weight regain is defined, a predominance of cross-sectional study designs, and widespread reliance on self-reported measures. Future longitudinal studies within Saudi populations are needed to strengthen the evidence and support the development of tailored postoperative interventions.
Obesity; Bariatric surgery; Weight regain; Physical activity; Sedentary behavior; Smoking; Dietary patterns; Saudi Arabia
When Two Risks Collide: Diabetes–Hypertension Clustering and Cardiovascular Outcomes in Saudi Adults Aged 25–50 Years — A Systematic Review
Doi : https://doi.org/10.5281/zenodo.19153531 Diabetes mellitus and hypertension are two of the most common and significant cardiometabolic problems worldwide and often occur together in the same patient; they also markedly increase the cardiovascular risk. In Saudi Arabia, rapid epidemiological transition, urbanisation, and lifestyle changes have had a role in the increase in the burden of both conditions, including among younger adults. While these individual conditions have been reported to be independent risk factors for cardiovascular morbidity and mortality, the extent of risk for their co-occurrence among the Saudi adult (25 to 50 years of age) population has not been fully synthesised. This is a systematic review of the relationship between diabetes alone, hypertension alone, and combined exposure to diabetes and hypertension with fatal and non-fatal CVDs in this population. Identification of studies published from 2010 to 2025 from major databases using predefined eligibility criteria was carried out. Eligible studies had to be able to diagnose those who had neither condition, those who had diabetes, those who had hypertension, and those who had both. Effect estimates were synthesised in a narrative way in order to evaluate the hypothesis that clustering has an additive or multiplicative excess cardiovascular risk. The review also discusses commonly-adjusted covariates, and the statistical adjustment is how the reported association is affected by statistical analysis. These findings aim to elucidate the cardiovascular implications suggested by cardiometabolic clustering in a younger Saudi population and may help us in the risk stratification and prevention strategies.
Diabetes mellitus; Hypertension; Cardiovascular disease; Risk clustering; Cardiovascular mortality; Saudi Arabia; Young adults; Systematic review
Systematic Review of the Prevalence and Diagnostic Patterns of Diabetic Peripheral Neuropathy in Saudi Arabia,
*]:pointer-events-auto scroll-mt-(--header-height)" dir="auto" tabindex="-1" data-turn-id="474fbe00-4b42-4a4b-a70b-84b5cfd9aa51" data-testid="conversation-turn-1" data-scroll-anchor="false" data-turn="user"> *]:pointer-events-auto scroll-mt-[calc(var(--header-height)+min(200px,max(70px,20svh)))]" dir="auto" tabindex="-1" data-turn-id="request-WEB:449f1817-bd78-4d6e-915c-74153b7a5aad-0" data-testid="conversation-turn-2" data-scroll-anchor="true" data-turn="assistant"> Doi https://doi.org/10.5281/zenodo.19154860 Background: Diabetic peripheral neuropathy (DPN), including its painful form (PDPN), is a frequent complication of diabetes associated with foot ulcers, increased amputation risk, and impaired quality of life. Reported prevalence in Saudi Arabia varies considerably, partly due to differences in diagnostic criteria and assessment methods. Objectives: To summarize Saudi evidence on the prevalence of DPN and PDPN and to compare the diagnostic case-ascertainment approaches used. Methods: MEDLINE (PubMed), Web of Science, and Scopus were searched from database inception to the final search date, with additional screening of reference lists. Observational studies conducted in Saudi Arabia that included individuals with medically confirmed type 1 or type 2 diabetes were eligible if they reported or allowed calculation of DPN or PDPN prevalence. Records were de-duplicated, screened in two phases, and evaluated at full text. Data extraction covered study setting, sample characteristics, ascertainment category (questionnaire/screening, bedside examination, electrodiagnostic testing, or combined methods), and prevalence outcomes. Findings were synthesized narratively. Results: Seventy-nine records were identified, and 12 cross-sectional studies (1998–2020) met inclusion criteria. Sample sizes ranged from 100 to 1,039 participants, comprising 4,556 individuals with diabetes. Prevalence estimates differed substantially according to diagnostic method and clinical setting. Bedside sensory testing combined with symptom assessment generally produced lower DPN prevalence estimates, typically affecting about one-fifth to two-fifths of participants. PDPN prevalence based on symptom questionnaires ranged from 29.1% to 65.3%. Overall DPN prevalence ranged from 8.8% when strict clinical sign criteria were applied to 69.2% when neuropathy was documented as a hospital complication. Electrodiagnostic assessments identified subclinical neuropathic changes in certain subgroups. Conclusion: DPN and PDPN are likely common among people with diabetes in Saudi Arabia; however, reported prevalence is strongly influenced by diagnostic methodology and clinical context. Future studies should adopt standardized definitions, validated assessment tools with clearly defined thresholds, and regionally representative sampling to produce comparable estimates and guide screening and preventive interventions.
diabetic peripheral neuropathy, painful diabetic neuropathy, prevalence, Saudi Arabia, diagnostic methods
Silent Spreaders: Asymptomatic COVID-19 Transmission Dynamics in University Dormitories
Background: University dormitories are high-density environments where asymptomatic SARS-CoV-2 carriers can contribute to rapid viral spread, often undetected until symptomatic cases appear. Objective: To quantify the contribution of asymptomatic infections to total COVID-19 transmission in university dormitories. Methods: A prospective cohort study was conducted in three universities in France between October 2022 and March 2023. Weekly PCR testing was performed on 1,842 dormitory residents, regardless of symptoms. Contact tracing identified secondary attack rates. Viral load (Ct values) was compared between asymptomatic and symptomatic cases. Results: Of 426 confirmed cases, 38.7% were asymptomatic at detection. The secondary attack rate from asymptomatic index cases was 11.8%, compared to 17.4% for symptomatic cases (p = 0.04). Median viral loads were not significantly different (Ct 23.1 vs. 22.7, p = 0.42). Asymptomatic carriers accounted for 28% of all transmission events. Conclusion: Asymptomatic SARS-CoV-2 carriers play a substantial role in transmission in dense living environments. Routine periodic testing in dormitories could prevent large outbreaks.
Asymptomatic Transmission, COVID-19, University Dormitories, Public Health Surveillance, Epidemiology
Copyright (c) 2025 International Journal of Hygiene and Environmental Health
The Last Mile Gap: Understanding Dropout Rates in the Measles Immunization Cascade in Rural Communities
Background: High initial vaccination uptake does not always translate to full immunization coverage due to dropouts before completion of the required doses. Understanding these gaps is critical for measles elimination goals. Objective: To identify the determinants of dropout between the first and second doses of measles-containing vaccine (MCV1 → MCV2) in rural primary health centers. Methods: A cross-sectional study was conducted in 48 rural health facilities in southern India between February and August 2023. Vaccination records of 4,326 eligible children aged 9–24 months were reviewed. Caregiver interviews captured sociodemographic and behavioral data. Logistic regression identified independent predictors of dropout. Results: The MCV1 coverage was 93.4%, while MCV2 coverage dropped to 78.9%, yielding a dropout rate of 15.5%. Major predictors included long travel distance to health facility (>5 km) (OR = 2.1, 95% CI: 1.6–2.8), caregiver’s lack of awareness about MCV2 (OR = 2.8, 95% CI: 2.1–3.7), and absence of reminder systems (OR = 3.4, 95% CI: 2.5–4.6). Mobile phone reminders reduced dropout odds by 42%. Conclusion: Strengthening reminder systems and improving caregiver awareness could substantially reduce measles immunization dropouts. Targeted interventions should focus on geographically remote households.
Measles, Immunization Dropout, Vaccination Coverage, Rural Health, Public Health
Outbreaks in the Concrete Jungle: A Multi-City Comparative Study of Emerging Infectious Diseases Across Sudan
Background: Rapid urbanization is reshaping global health landscapes, particularly in low- and middle-income countries (LMICs). In Sudan, urban expansion driven by conflict, displacement, and population growth has intensified public health challenges, heightening vulnerability to emerging infectious diseases (EIDs). This study investigates the relationship between urbanization factors—population density, infrastructure development, and healthcare accessibility—and the transmission of EIDs in Sudanese cities. Additionally, it evaluates the effectiveness of targeted public health interventions in mitigating disease transmission risks . Methods: A multi-city comparative analysis was conducted across five Sudanese cities: Port Sudan, Kassala, Al-Gadaref, Al Daba, and Dongola. Data were sourced from governmental health records, GIS mapping, and epidemiological reports. Statistical analyses, including multivariate regression, spatial analysis, and time-series trends, were employed to assess the association between urbanization factors and disease incidence. Results: A significant correlation was identified between population density and disease incidence, with Port Sudan and Kassala exhibiting the highest rates. Cities hosting large displaced populations faced heightened disease risks, primarily due to overcrowded living conditions and restricted access to healthcare. In contrast, cities with robust healthcare infrastructure, higher vaccination coverage, and improved sanitation experienced significantly lower disease incidence rates. Notably, healthcare access and vaccination coverage demonstrated strong negative correlations with disease transmission. Conclusion: Urbanization significantly influences infectious disease transmission patterns in Sudanese cities. However, localized public health interventions, such as enhanced healthcare infrastructure, targeted vaccination programs, and improved sanitation systems, can effectively mitigate these risks. Policymakers should adopt city-specific strategies that address the unique urbanization dynamics and health challenges of each region.
Urbanization, Emerging Infectious Diseases, Public Health Interventions, Population Density, Healthcare Access, Sudan, Displacement, Sanitation
Whispers of the Outbreak: Modeling Hidden Cholera Transmission in Informal Settlements
Background: Cholera outbreaks in informal settlements are often under-reported due to limited surveillance infrastructure, stigma, and delayed health-seeking behaviors. Traditional surveillance systems fail to capture these "silent" transmission zones, leading to underestimated risk and delayed interventions. Objective: To develop and validate a predictive model for identifying hidden cholera transmission clusters in urban informal settlements using syndromic, spatial, and environmental data. Methods: A retrospective cohort analysis was conducted using health and environmental data from 47 informal settlements in Dhaka, Bangladesh and Nairobi, Kenya, collected between January 2020 and June 2023. Reported diarrhea cases, rainfall, latrine proximity, population density, and mobile clinic reports were integrated into a spatial-temporal Bayesian model. Hidden transmission was inferred by comparing observed vs. expected case distributions and validating with stool sample positivity rates. Results: The model identified 26 high-probability hidden clusters where case reporting was below 30% of predicted burden. Incorporating environmental variables improved the model’s AUC from 0.71 to 0.88. Areas within 150 meters of open drainage and high foot traffic were 3.2× more likely to host hidden clusters (OR: 3.2, 95% CI: 2.1–5.0, p < 0.001). Community-based stool testing confirmed Vibrio cholerae in 17 of 26 flagged clusters. Conclusion: Silent cholera transmission in informal settlements can be effectively modeled using combined syndromic and spatial predictors. This approach reveals outbreak dynamics overlooked by routine surveillance and supports early, targeted intervention. Integrating such models into city-level health dashboards could revolutionize outbreak prediction in vulnerable communities.
Cholera Modeling, Informal Settlements, Outbreak Detection, Spatial Epidemiology, Hidden Transmission
Beyond the Numbers: Underreported Noncommunicable Disease Burden in Nomadic Communities
Background: Nomadic populations are often excluded from routine health surveillance systems, leading to potential underreporting of noncommunicable diseases (NCDs) such as hypertension, diabetes, and respiratory disorders. This data invisibility hampers targeted public health interventions. Objective: To estimate the prevalence of selected NCDs in nomadic communities and compare self-reported versus objectively measured health outcomes. Methods: A mobile health screening initiative was conducted across four nomadic pastoralist regions in western China and Inner Mongolia between 2022 and 2024. A total of 612 adults were assessed using standardized NCD screening protocols (BP, HbA1c, spirometry). Self-reported health surveys were also collected. Prevalence estimates were compared to regional health database reports. Results: Hypertension prevalence based on direct BP measurement was 29.6%, while self-reported diagnosis was only 11.2% (p < 0.001). Diabetes (HbA1c ≥6.5%) was found in 13.4% of participants, with just 3.9% aware of their status. Chronic respiratory symptoms were noted in 26.1%, yet only 7.3% reported any previous evaluation. Compared to national registry data, NCD prevalence in these populations was underreported by 2.5 to 4.8-fold. Conclusion: NCDs are significantly underdetected in nomadic communities due to access barriers and reporting gaps. Traditional household survey designs may not capture mobile groups. Integrating mobile clinics with geospatial tracking and culturally sensitive health engagement strategies is essential to ensure equity in NCD surveillance and care.
Nomadic Health, Noncommunicable Diseases, Underreporting, Health Equity, Mobile Screening
Heat Without Warning: Occupational Heat Stress and Cognitive Impairment Among Outdoor Workers
Background: With rising global temperatures, outdoor laborers face increasing risk of heat-related illnesses. Beyond physical health, prolonged heat exposure may impair cognitive function and workplace safety, yet these effects remain poorly quantified. Objective: To assess the relationship between ambient heat exposure and cognitive performance among outdoor workers in urban construction and agriculture sectors. Methods: A prospective observational study was conducted among 244 outdoor workers in southern Italy during summer 2023. Participants underwent cognitive testing (working memory, reaction time, attention span) at baseline and after 6-hour work shifts across varying heat index categories. Continuous skin temperature, hydration status, and WBGT (Wet Bulb Globe Temperature) were monitored. Multivariable regression controlled for age, sleep, BMI, and shift duration. Results: Cognitive decline was observed in 63.9% of workers exposed to WBGT >30°C compared to 28.7% under moderate conditions (p < 0.001). Reaction time worsened by 17.3% on average (p = 0.004), and working memory scores dropped by 22.1% (p < 0.001). Heat exposure >6 hours was independently associated with moderate-to-severe cognitive impairment (OR: 3.6, 95% CI: 2.2–5.9). Hydration mitigated some decline, though not entirely. Conclusion: Chronic occupational heat stress impairs cognition and may compromise worker safety and productivity. Workplace policies should incorporate heat index forecasting, rest breaks, and hydration protocols, especially in regions facing escalating temperatures under climate change.
Heat Stress, Occupational Health, Cognitive Function, WBGT, Outdoor Workers
Background: Cholera outbreaks in informal settlements often remain under-detected due to poor surveillance, unregulated migration, and limited access to testing. Conventional surveillance may overlook the true burden and transmission routes of cholera in such high-density, underserved environments. Objective: To develop a predictive spatial-temporal model of cholera transmission in informal urban settlements, identifying hidden clusters and evaluating key transmission drivers. Methods: A retrospective analysis was conducted in two major informal settlements in Dhaka and Lagos between January 2018 and December 2023. Reported cholera cases (n = 1,728) were geo-tagged, and wastewater sampling data were integrated with demographic and environmental indicators (e.g., sanitation coverage, water source type, rainfall patterns). A Bayesian spatio-temporal model was used to infer hidden transmission pathways. Model outputs were compared against known outbreaks for validation. Results: Modeling revealed 3 previously undetected transmission hotspots with high posterior probabilities (>0.9). These areas had poor sanitation access (<35%) and population densities >50,000/km². Rainfall intensity was a strong predictor of cluster emergence (p < 0.001), with transmission peaks following rainfall spikes by 7–10 days. Integration of wastewater signals increased detection sensitivity by 26.3%. Areas missed by standard surveillance accounted for an estimated 41.5% of total cases. Conclusion: Cholera transmission in informal settlements is shaped by complex, underrecognized spatial patterns. Traditional case reporting underestimates the burden. Integration of wastewater monitoring and probabilistic modeling enhances early detection and can guide targeted intervention zones. Investing in data infrastructure and real-time geospatial tools may dramatically improve outbreak containment.
Dust in the Lungs: A Systematic Mapping of Airborne Particulate Exposure Near Open Waste Sites
Background: Open and poorly managed waste disposal sites are common in many low- and middle-income countries, releasing hazardous airborne particles into nearby communities. Children and informal workers are especially vulnerable to chronic exposure, yet spatially detailed risk assessments remain limited. Objective: To map airborne particulate matter (PM) concentrations around open waste sites and evaluate associated respiratory health risks among adjacent populations. Methods: A geospatial environmental health study was conducted in three regions of northern India. Twenty open waste sites were selected based on size and population density within a 3 km radius. PM2.5 and PM10 levels were measured using portable air monitors at four directional zones (0.5 km, 1 km, 2 km, 3 km) during both dry and wet seasons. Health surveys and spirometry testing were conducted among 684 residents, including 122 informal waste pickers and 185 children aged 6–14 years. Results: PM2.5 concentrations exceeded WHO limits in 94% of dry-season readings at ≤1 km distance (mean: 94.2 μg/m³), with peak levels at 0.5 km. Lung function abnormalities (FEV1 <80% predicted) were found in 37.5% of waste pickers and 21.2% of children within 1 km zone, compared to 8.4% in those >2 km (p < 0.001). GIS heatmaps revealed consistent pollution gradients radiating from site centers. Logistic regression confirmed distance <1 km as an independent risk factor for abnormal spirometry (OR: 3.1, 95% CI: 2.0–4.8). Conclusion: Living and working near open waste sites exposes individuals to harmful levels of airborne particulate matter, with measurable respiratory harm. Urban planning and environmental health policy must prioritize waste site remediation, zoning enforcement, and protective measures for nearby populations.
Air Pollution, PM2.5, Waste Sites, Respiratory Health, Environmental Exposure
Toxic Silence: The Mental Health Impact of Chronic Industrial Exposure in Adolescents
Background: In many industrial zones, adolescents reside near factories emitting chronic levels of noise, chemical fumes, and heavy metals. While physical health consequences have been documented, the psychological burden of such long-term exposure remains largely invisible. Objective: To examine the association between proximity to industrial zones and mental health outcomes among adolescents, including anxiety, depression, and sleep disturbance. Methods: A cross-sectional study was conducted among 728 adolescents aged 12–18 living within 5 kilometers of three major industrial hubs in southern China. Participants completed validated mental health screening tools (PHQ-9 for depression, GAD-7 for anxiety, and PSQI for sleep quality). Blood and hair samples were collected to measure lead and cadmium levels. Air quality data (PM2.5, SO₂) were obtained from monitoring stations over the preceding 12 months. A control group (n=312) resided ≥20 km away from any industrial zone. Results: Adolescents in exposed zones had significantly higher rates of moderate-to-severe anxiety (26.3% vs. 10.9%, p < 0.001) and depression (21.8% vs. 8.1%, p < 0.001). Elevated blood lead (>5 µg/dL) was found in 18.7% of exposed participants vs. 4.6% in controls. Hair cadmium levels were 2.4× higher on average in the exposed group (p < 0.001). Proximity to industrial zone (<2 km) was independently associated with poor sleep scores (OR: 2.8, 95% CI: 1.9–4.0). Conclusion: Adolescents exposed to chronic industrial pollution may silently bear a significant psychological toll. Beyond environmental regulation, mental health screening and support programs should be integrated into health services for communities near industrial developments.
Adolescent Mental Health, Industrial Pollution, Lead Exposure, Anxiety, Environmental Health
The Silent Threshold: Undiagnosed Hypertension Among Urban Refugees in Post-Conflict Zones
Background: Hypertension is a leading non-communicable disease globally. However, in refugee populations living in urban post-conflict areas, the silent burden of undiagnosed hypertension remains largely invisible to health systems. Objective: To assess the prevalence and predictors of undiagnosed hypertension among adult refugees residing in urban post-conflict settlements and examine the barriers to diagnosis and care. Methods: A cross-sectional survey was conducted in 2024 among 812 adult refugees (aged 18–65 years) living in three urban refugee camps in a post-conflict zone of northern Lebanon. Blood pressure measurements were taken using WHO-recommended digital devices. Individuals were considered hypertensive if SBP ≥140 mmHg or DBP ≥90 mmHg without prior diagnosis. Demographic, socioeconomic, and health access data were collected through structured interviews. Logistic regression was used to identify predictors of undiagnosed hypertension. Results: Undiagnosed hypertension was found in 27.6% of participants. Older age (>45 years), BMI ≥30, and previous trauma exposure were significant predictors (OR = 2.3, 95% CI: 1.6–3.5; OR = 1.8, 95% CI: 1.2–2.6; OR = 1.5, 95% CI: 1.0–2.2, respectively). Despite 84% of respondents reporting recent interaction with a healthcare provider, only 19% had ever had their blood pressure measured. Key barriers included lack of awareness (56%), cost (33%), and mistrust in the health system (28%). Conclusion: Undiagnosed hypertension among urban refugee populations represents a neglected health crisis. Despite access to some services, gaps in screening, trust, and health literacy allow this condition to silently progress. Integrating routine NCD screening into refugee primary care systems is essential to avert long-term complications.
Undiagnosed Hypertension, Urban Refugees, Non-Communicable Diseases, Post-Conflict Health, Health Access
Water’s Forgotten Path: Contaminated Household Storage as a Source of Diarrheal Disease in Rural Areas
Abstract: Background: While global water access has improved, rural households often rely on basic collection methods and store water in unsanitary containers. This overlooked storage step may contribute substantially to diarrheal disease transmission among children under five. Objective: To evaluate the microbiological quality of stored household water and its association with diarrheal incidence in rural communities across three low-resource districts. Methods: A cross-sectional survey and water sampling initiative were conducted across 9 villages in rural areas of southern China and eastern Africa between April and August 2024. A total of 516 households were enrolled. Water samples were collected at both source and storage container levels and tested for E. coli, total coliforms, and turbidity. Household demographics, sanitation practices, and 2-week diarrhea history among children were recorded. Multivariable logistic regression assessed the association between contamination and diarrheal outcomes. Results: While 89.1% of water sources met WHO microbiological standards, only 53.6% of stored water samples remained within acceptable limits. E. coli was detected in 41.8% of stored water samples compared to 9.7% at source (p < 0.001). Diarrhea prevalence among under-5 children was 22.4%, with higher risk in households using wide-mouth, uncovered containers (OR: 2.9, 95% CI: 1.8–4.6, p < 0.001). Container cleaning frequency less than once weekly was also independently associated with illness (p = 0.012). Conclusion: Household water storage practices represent a critical but underappreciated transmission point for diarrheal disease. Interventions must go beyond access and address container hygiene, design, and behavioral habits. Community-level education on safe storage could significantly reduce preventable childhood illness.
Diarrhea, Household Water Storage, Rural Health, E. coli Contamination, Child Health
Challenges in Hand Hygiene Practice: Understanding Human Behavior Barriers
Background: Despite global awareness campaigns and the availability of sanitation infrastructure, hand hygiene compliance remains persistently low in both healthcare settings and the general public. Behavioral and cognitive barriers are often overlooked in hygiene promotion strategies. Objective: To investigate behavioral, cultural, and perceptual factors influencing hand hygiene compliance in healthcare workers and caregivers in low-resource primary health facilities. Methods: A mixed-methods study was conducted in 14 public primary health centers in rural France between May and September 2024. Observational audits of 211 healthcare workers (nurses, aides, physicians) were performed using the WHO “5 Moments” framework. Semi-structured interviews (n=52) explored beliefs, risk perceptions, social norms, and facility-level barriers. Quantitative compliance data were analyzed using chi-square and multivariable logistic regression. Results: Overall hand hygiene compliance was 41.6%. Compliance was significantly lower before patient contact (27.9%) versus after contact (54.3%, p < 0.001). Key behavioral barriers included perceived time pressure (reported by 68.2%), absence of immediate feedback (61.5%), and low perceived infection risk in routine tasks (44.8%). Workers with high workload (≥15 patients/shift) had 2.3 times lower odds of compliance (OR = 0.43; 95% CI: 0.31–0.59, p < 0.001). Qualitative themes revealed the impact of workplace culture and role modeling, especially among junior staff. Conclusion: Hand hygiene compliance is not solely a matter of availability—it is shaped by complex behavioral and organizational dynamics. Interventions that combine behavioral nudges, peer accountability, and targeted education may be more effective than infrastructure alone. Cultural tailoring and real-time feedback mechanisms should be central to future programs.
Hand Hygiene Practices Understanding Human Behavior Barrier
Waterborne Disease Outbreaks: Risk Assessment and Response Strategies in Urban Slums
Background: Urban slums, characterized by overcrowding and poor sanitation, are hotspots for waterborne disease outbreaks. This study evaluates risk factors and public health responses in urban slum environments. Methods: A mixed-methods approach was used, including a retrospective analysis of outbreak data from 2015 to 2023 and in-depth community surveys. Cholera, typhoid fever, and hepatitis A were the primary diseases of focus. Environmental water samples were tested for contamination levels, and public health interventions were mapped. Results: Cholera incidence was significantly higher in areas with inadequate water filtration (p < 0.001). Typhoid fever outbreaks correlated with open sewage exposure and limited vaccination coverage. Public health interventions, including water chlorination and health education, reduced outbreak severity by 35% over three years. Conclusion: Targeted public health measures are effective in controlling waterborne diseases in urban slums. Scaling these interventions could substantially reduce morbidity and mortality rates in vulnerable communities.
Waterborne Diseases, Public Health, Urban Slums, Cholera, Typhoid Fever, Outbreak Control
Climate Change and Vector-Borne Diseases: Emerging Threats and Adaptive Strategies
Background: Climate change has expanded the geographic range of vector-borne diseases, increasing public health risks in previously unaffected areas. This study evaluates the impact of rising temperatures and shifting precipitation patterns on the incidence of vector-borne diseases. Methods: Data from global disease surveillance systems were analyzed from 2010 to 2023. Geographic Information System (GIS) mapping and climate modeling were used to identify high-risk zones for diseases such as malaria, dengue, and Zika. Seasonal variations and climate anomalies were correlated with outbreak spikes. Results: Regions with average temperature increases of 1.5°C experienced a 22% rise in dengue incidence (p < 0.01), while malaria spread to higher altitudes. GIS mapping identified new transmission hotspots in temperate regions previously considered low-risk. Conclusion: Climate change is reshaping the epidemiological landscape of vector-borne diseases. Adaptive public health strategies, including vector control and climate-resilient infrastructure, are necessary to mitigate future risks.
Climate Change, Vector-Borne Diseases, Public Health, GIS Mapping, Malaria, Dengue
Global Trends in Antimicrobial Resistance: A Systematic Review and Meta-Analysis
Background: Antimicrobial resistance (AMR) presents a global health threat, complicating the treatment of infectious diseases. Understanding geographic and temporal trends is crucial for effective public health interventions. Methods: A systematic review and meta-analysis were conducted, encompassing 142 studies from 2015 to 2024 across 54 countries. Data on resistance rates for Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae were extracted. Random-effects modeling was used to estimate pooled resistance rates and assess temporal trends. Results: Globally, AMR rates increased by an average of 4.3% annually, with the highest growth observed in low- and middle-income countries (p < 0.001). E. coli resistance to fluoroquinolones reached 39%, while S. aureus showed a 21% resistance rate to methicillin. Temporal analysis revealed a linear escalation in resistance rates, correlating with antibiotic consumption patterns. Conclusion: AMR continues to rise globally, particularly in resource-limited settings. Enhanced surveillance, rational antibiotic use, and global cooperation are essential to curb resistance trends.
Antimicrobial Resistance, Public Health, Systematic Review, Meta-Analysis, Global Health
Air Pollution and Respiratory Health: A Longitudinal Study of Urban Populations in High-Density Cities
Background: Urbanization and industrialization have significantly increased air pollution levels, raising concerns over long-term respiratory health impacts. This study examines the correlation between air pollution exposure and respiratory illnesses in high-density cities. Methods: A longitudinal cohort of 2,500 adults living in urban areas with high pollution indices was followed over five years. Particulate matter (PM2.5, PM10) and nitrogen dioxide (NO₂) concentrations were measured continuously. Spirometry tests and health surveys were conducted annually to assess respiratory function and symptom prevalence. Results: Prolonged exposure to PM2.5 above WHO guidelines was associated with a 24% increase in chronic obstructive pulmonary disease (COPD) risk (p < 0.001) and a 16% increase in asthma incidence (p < 0.01). Spirometry results showed a mean annual decline in FEV1 of 3.1% among high-exposure participants, compared to 1.8% in low-exposure groups. Conclusion: Long-term exposure to urban air pollution significantly exacerbates respiratory health risks. Mitigation strategies focusing on emission reductions are essential to improve health outcomes in densely populated regions.
Air Pollution, Respiratory Health, COPD, Urbanization, Public Health, Environmental Epidemiology
Digital Epidemiology: Harnessing Social Media Analytics for Early Detection of Infectious Disease Outbreaks
Background: The rise of digital communication platforms has created new opportunities for early disease detection through digital epidemiology. Social media data, when analyzed correctly, can provide real-time signals of infectious disease outbreaks. This study investigates the feasibility of using social media analytics for early outbreak detection. Methods: A retrospective analysis was performed on Twitter and Facebook posts related to influenza-like illness (ILI) and COVID-19 from 2020 to 2024. Natural language processing (NLP) and geolocation data were applied to detect outbreak clusters in near real-time. Confirmatory data were cross-referenced with official public health surveillance reports. Predictive modeling was conducted using machine learning algorithms to estimate outbreak spread. Results: Digital signals of ILI outbreaks were detected an average of 12 days earlier than conventional surveillance systems (p < 0.01). Predictive models achieved 89% accuracy in forecasting outbreak size and geographic spread within two weeks of detection. Correlation with official health data was strong (R² = 0.87). Conclusion: Social media analytics can enhance early detection of infectious disease outbreaks, offering a valuable complement to traditional surveillance methods. Integrating digital epidemiology into public health strategies may improve response times and reduce transmission.
Digital Epidemiology, Infectious Disease, Outbreak Detection, Social Media Analytics, Public Health Surveillance
Epidemiological Trends of Non-Communicable Diseases in Humanitarian Settings: A Neglected Burden in Displaced Communities
Abstract: Non-communicable diseases (NCDs) such as hypertension and diabetes are rising in displaced populations but often overlooked. This study analyzed 4,500 adults in IDP camps in Sudan, Yemen, and Lebanon. Hypertension affected 26.4%, diabetes 14.1%, and cardiovascular disease 8.7%. Only 23% received regular treatment; 58% lacked follow-up. NCD clinics were present in only 31% of camps. Risk factors included inactivity (62%), high-salt diet (39%), and smoking (21%). Undiagnosed cases accounted for 49% of total burden. Female hypertension was 29%, male diabetes 15.8%. Stroke, kidney failure, and amputations affected 7.2% of cases. Integrating NCD services into emergency health systems could prevent over 35% of complications.
Non-Communicable Diseases, Refugee Camps, Humanitarian Health Systems, Chronic Disease Management, Epidemiology
Community Health Worker Impact on Maternal and Child Health in Displaced Populations: A Prospective Cohort Study
Abstract: Abstract (Expanded Version): Background: Internally displaced populations (IDPs) face disproportionate maternal and child health challenges due to disrupted services, poor environmental hygiene, and limited health system access. This study aimed to evaluate the impact of a Community Health Worker (CHW) intervention on maternal and neonatal health outcomes in humanitarian settings across Chad, Sudan, and Somalia. Methods: A prospective cohort study was conducted among 1,200 pregnant women in six IDP camps from January 2022 to December 2023. Baseline data were compared with post-intervention outcomes over 12 months. CHWs were deployed with a coverage ratio of 1:50 households, delivering antenatal education, referral services, immunization support, and home-based care. Key indicators included antenatal care (ANC) attendance, institutional deliveries, immunization rates, neonatal mortality, and patient satisfaction. Data were analyzed using chi-square tests and logistic regression models. Results: Antenatal care (ANC) attendance improved significantly from 41.2% (95% CI: 38.1–44.3%) at baseline to 96.4% (95% CI: 94.2–98.1%) post-intervention (p < 0.001). Institutional delivery rates increased from 29.3% to 67.1% (p = 0.002). Full immunization coverage among infants under 12 months rose from 52.7% to 98.9% (p < 0.001). Neonatal mortality declined from 32.1 per 1,000 live births to 18.0 per 1,000, reflecting a 43.9% reduction (p = 0.004). The CHW intervention also significantly increased patient satisfaction, with 84.3% of mothers reporting high satisfaction scores, up from 48.5% pre-intervention (p < 0.001). Despite these gains, structural barriers remained: only 63.5% of CHWs received formal medical training, and 41.1% reported insufficient medical supplies, limiting service effectiveness in some zones. Multivariate logistic regression indicated that CHW exposure was independently associated with increased ANC attendance (Adjusted Odds Ratio [AOR]: 4.82; 95% CI: 3.44–6.75; p < 0.001) and reduced neonatal mortality (AOR: 0.48; 95% CI: 0.29–0.78; p = 0.005). Conclusion: CHW-led maternal and child health programs in humanitarian contexts can significantly improve access to essential services and reduce neonatal mortality by over 40%, even in low-resource, crisis-affected settings. The study underscores the urgency of scaling and institutionalizing CHW interventions into national emergency response frameworks to improve health outcomes in displaced populations.
Maternal Health, Community Health Workers, Displacement, Child Health Outcomes, Humanitarian Public Health
Effectiveness of Water, Sanitation, and Hygiene (WASH) Interventions in Humanitarian Settings: A Meta-Analysis of Diarrheal Disease Reduction
Abstract: Water, sanitation, and hygiene (WASH) interventions are essential for reducing disease burden in humanitarian emergencies. Diarrheal diseases contribute to 30–50% of child mortality in displacement settings. This meta-analysis includes 24 studies involving 188,000 participants across 14 countries between 2010 and 2023. Findings show WASH interventions reduce diarrheal disease incidence by 39% (RR: 0.61; 95% CI: 0.54–0.70). Chlorinated water supply led to a 45% reduction, while hand hygiene education reduced incidence by 32%. Camps with ≥75% safe water coverage had a 51% decrease in diarrheal cases compared to 19% in low-coverage camps. However, 41% of interventions lacked long-term monitoring. Only 37% distributed hygiene kits, and latrine-to-user ratios averaged 1:76, exceeding SPHERE standard (1:50). The study recommends improved hygiene promotion, timely latrine construction, and quality water monitoring to achieve sustainable outcomes.
Diarrhea Prevention, WASH, Humanitarian Epidemiology, Refugee Health, Systematic Review