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Frontiers in Physics

Frontiers Media SA

Preprints posted in the last 7 days, ranked by how well they match Frontiers in Physics's content profile, based on 20 papers previously published here. The average preprint has a 0.03% match score for this journal, so anything above that is already an above-average fit.

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Limitations of cross-border containment strategies for Bundibugyo ebolavirus

Middleton, C.; Larremore, D.

2026-06-08 epidemiology 10.64898/2026.06.04.26354820 medRxiv
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An ongoing outbreak of Bundibugyo virus disease (BVD) in the Democratic Republic of the Congo was deemed a public health emergency of international concern in May 2026. To prevent cross-border importation, many countries, including the United States, Canada, India, Thailand, and Kenya have already proposed containment strategies, and others are likely to follow suit. How well (or poorly) are screening and quarantine containment measures are likely to work? We leverage established epidemiological theory and develop a mathematical model of traveler screening and post-arrival quarantine for BVD to answer this question. We find that traveler screening via symptom screening or molecular testing will miss the majority of infected travelers, and should be complemented by post-arrival quarantine and monitoring of sufficient duration to detect those with long incubation periods. Our findings underscore the limitations of border screening and the importance of complementary measures like post-arrival quarantine to prevent local importation of BVD.

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Investigation of the continuous spread of SARS-CoV-2 in the post pandemic time - Insights into the reason for the sustained spread despite the establishment of population immunity

Yi, B.

2026-06-08 epidemiology 10.64898/2026.06.05.26355009 medRxiv
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In spite of well-established global immune landscape, SARS-CoV-2 is still able to further spread and continue causing infection waves. The current understanding about the reason behind is limited, and it is still difficult to predict the evolution or spreading tread of SARS-CoV-2. Therefore, it is necessary to investigate whether the establishment of population immunity has changed the virus evolution or spreading pattern. In this investigation, one overall analysis of the SARS-CoV-2 spreading in the past several years have been carried out through one thorough genomic epidemiology study, with Germany being chosen as one representative location in view of the systemic efforts for genomic surveillance. The growth advantage of a few predominant variants in its early spreading period has been evaluated through a logistic regression model. The results have revealed that the major circulating SARS-CoV-2 variants since 2023 are mainly derived from the Omicron BA.2 family. Since middle of 2024, most predominant variants were produced primarily through recombination, indicating that the evolution derived from recombination might be the major driving force for the continuous spread of SARS-CoV-2 despite the existence of population immunity. Furthermore, the lower growth advantage of recently emerged variants might possibly lead to a tread of reduction in the frequency of infection wave. The information revealed from this investigation suggests that although short-term spreading tread can be affected by specific virus feature as well as local immunity landscape, the long-term spreading tread is mainly decided by the genomic diversity of the viruses, and can be predicted through phylogenetic and genomic epidemiology investigation. The results have emphasized the importance of maintaining the efforts for genomic surveillance of SARS-CoV-2, which is essential from both medical and research perspectives.

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A wealth index based on two-component polychoric principal component analysis reduces urban bias and improves socioeconomic classification in low- and middle-income country surveys: a validation study using LSMS surveys

Vidaletti, L. P.; Dos Santos, A. M.; Hellwig, F.; Barros, A. J. D.

2026-06-08 epidemiology 10.64898/2026.06.01.26354245 medRxiv
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Background: The traditional wealth index, based on principal component analysis (PCA), used in the Demographic and Health Surveys (DHS) and Multiple Indicator Cluster Surveys (MICS), suffers from urban bias, distorting estimates of health inequality. We compared the traditional index (PEAR1) with an alternative two-component polychoric PCA index (POLY2) using annual expenditure from 12 LSMS surveys as the gold standard to determine which provides more accurate SEP measures for equitable policy targeting. Methods: We compared the traditional wealth index (PEAR1) with a two-component polychoric PCA approach (POLY2) using 12 LSMS (Living Standards Measurement Study) surveys (2015-2022) from 12 African countries. Annual household consumption expenditure was the gold standard. We assessed agreement using weighted Cohen's kappa and validated against education (proportion of households with secondary or higher education) using the concentration index (CIX) and slope index of inequality (SII). Results: The POLY2 index showed higher agreement with expenditure quintiles (average national weighted kappa = 43.3%) than the PEAR1 index (35.1%), with notable improvements in urban (43.5% vs. 27.5%) and rural (35.3% vs. 22.4%) areas. POLY2 also attenuated extreme household distributions observed in PEAR1. Education validation showed that POLY2 produced intermediate inequality gradients between the flatter expenditure-based gradient and the steeper PEAR1-based gradient. Conclusion: The POLY2 wealth index is superior to the traditional index, reducing urban-rural bias and providing more accurate socioeconomic classifications. Its adoption in large-scale surveys such as DHS and MICS is recommended to improve equitable monitoring of health inequalities in low- and middle-income countries.

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Socio-demographic Correlates of Prolonged Amenorrhea and Menopausal Transition among Nigerian Women Aged 30-49: Evidence from the 2024 Nigeria Demographic and Health Survey

Ogunsemoyin, O.; Ayinmoro, A. D.

2026-06-09 public and global health 10.64898/2026.06.06.26355063 medRxiv
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Introduction Menopause is a central marker of reproductive ageing, but national evidence on menstrual cessation among Nigerian women in the late reproductive ages remains limited. This study examined the prevalence and socio-demographic correlates of prolonged amenorrhea/possible menopausal transition among Nigerian women aged 30-49 years. Methods The study used the women's individual recode file from the 2024 Nigeria Demographic and Health Survey. The analytic sample was restricted to women aged 30-49 years, excluding women who were currently pregnant, currently or postpartum amenorrheic, and those with invalid or special responses on time since last menstrual period. The final sample comprised 14,223 women. The outcome combined women whose last menstrual period occurred 12 or more months before the survey, and women reported as being in menopause. Weighted descriptive statistics, design-adjusted bivariate tests and survey-weighted binary logistic regression were used. Results The weighted prevalence of prolonged amenorrhea/possible menopausal transition was 7.6%. Prevalence rose from 1.2% among women aged 30-34 years to 23.6% among women aged 45-49 years. In the adjusted model, women aged 35-39 years (OR=1.64; p=0.030), 40-44 years (OR=6.20; p<0.001) and 45-49 years (OR=24.51; p<0.001) had higher odds than women aged 30-34 years. Primary education (OR=1.65; p=0.004), middle wealth status (OR=1.37; p=0.043) and poorest wealth status (OR=1.60; p=0.024) were associated with higher odds. Muslim affiliation (OR=0.72; p=0.024) and traditional contraceptive use (OR=0.24; p<0.001) were associated with lower odds. Conclusion Prolonged amenorrhea/possible menopausal transition among Nigerian women aged 30-49 is strongly age-patterned and socially differentiated. The findings support the need to make midlife menstrual health more visible within reproductive, family planning and primary healthcare services. Because the measure is based on survey-reported menstrual recency, it should not be interpreted as clinically confirmed natural menopause.

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Local Influenza Forecasts Outperform State-Level Forecasts in the United States

Kim, D.; Pasco, R.; Johnson, K. E.; Fox, S. J.; Reich, N. G.; Meyers, L. A.

2026-06-08 infectious diseases 10.64898/2026.06.04.26354836 medRxiv
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Accurate outbreak forecasts are critical for timely and effective public health response. In the United States, however, most forecasts are produced at the state level, which can mask substantial sub-state heterogeneity and limit their utility for local planning. We generated and evaluated forecasts of the percentage of Emergency Department visits attributable to influenza across 173 large metropolitan Health Service Areas (HSAs) using a gradient boosting quantile regression (GBQR) model, and compared their accuracy to forecasts derived from state-level data alone. At a one-week, two-week and three-week horizon, local forecasts outperformed state-based forecasts in 98.8%, 90.8%, and 78.6% of HSAs, respectively, achieving mean weighted interval scores that were on average a 39.2% lower (95% range: 5.9% to 76.7%), 19.6% lower (-6.3% to 59.5%) , and 11.4% lower (-11.7% to 44.9%), respectively. The performance advantage of local forecasting was strongest in HSAs representing a smaller share of their state's population and increased with the proportion of the HSA population living in urban areas and the number of metropolitan areas within a state. These results, based on an analysis of HSAs with populations greater than 250,000, demonstrate that fine-scale modeling can substantially improve forecast accuracy and highlight the potential value of local forecasts for outbreak preparedness and response.

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Temporal and climatic drivers of uncomplicated malaria in Ghana: A Region Generalised Additive Model analysis.

Akurugu, E.; Awine, T.; Seidu, B.; Peprah, N. Y.; Mohammed, W.; Boateng, P.; Abiwu, P. H. A. K.; Silal, S. P.

2026-06-09 infectious diseases 10.64898/2026.06.06.26355054 medRxiv
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Abstract Background Malaria remains a major public health challenge in Ghana, despite recent reductions in cases due to various interventions. The endemicity of the disease varies across regions, influenced by diverse seasonal and temporal factors that support mosquito proliferation and malaria cases. This study used a Generalised Additive Models to explore the impact of weather conditions on malaria cases in Ghana. Methods Generalised Additive Models were used to examine the nonlinear effects of weather conditions on malaria cases. Monthly aggregated malaria cases from the District Health Information Management System II and average monthly rainfall and temperature data from the Ghana Meteorological Agency were analysed, covering 2012 to 2023. Regional Generalised Additive Models incorporating weather variables were developed, fitted, and validated against observed data using model diagnostics to identify the most suitable model for each region. Results The analysis revealed complex temporal patterns in malaria cases across Ghana, influenced by seasonal and long-term trends. Regions constituting the Coastal and Transitional Forest zones exhibited bimodal peak malaria seasons, while the Guinea Savannah showed a unimodal peak. Significant interactions between rainfall and temperature were identified, particularly in the Eastern region, where higher rainfall combined with temperatures around 27-28 {degrees}C were associated with higher malaria cases, reflecting the complex and region-specific nature of meteorological influences. Conclusions The findings point to the dynamic and heterogeneous nature of malaria caseloads in Ghana, emphasising the need for region-specific control strategies tailored to local climatic conditions. A key recommendation is the systematic integration of meteorological data into the National Malaria Data Repository to enable continuous monitoring of climatic influences and support timely, evidence-based intervention decisions. Future research should incorporate socio-economic factors, intervention coverage data, vector surveillance, and demographic characteristics into mathematical modelling frameworks for a more comprehensive understanding of malaria cases in Ghana.

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Early assessment of potential airline-mediated importation risk during the 2026 DRC-Uganda Bundibugyo virus disease outbreak

Kinoshita, R.; Suzuki, M.; Yoneoka, D.

2026-06-09 public and global health 10.64898/2026.06.01.26354569 medRxiv
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During the 2026 Bundibugyo virus disease outbreak in the Democratic Republic of the Congo and Uganda, we projected potential airline-mediated importation risk using contemporary airline network and an externally calibrated Ebola importation hazard. Effective-distance analyses identified major international hub countries, including Belgium, France, South Africa, Kenya, and the United Arab Emirates, as higher-probability gateways within 30 days. These early projections provide a reproducible framework for real-time international situational awareness, while emphasizing that importation risk does not imply local transmission risk.

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Reduced nighttime smartphone use among cohabiting partners: a longitudinal study under the lens of social control of health behaviors theory

Klasson, T. A.; Rod, N. H.; Zucco, A. G.

2026-06-12 epidemiology 10.64898/2026.06.09.26355243 medRxiv
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Objective: We examined the link between cohabitation with a partner and nighttime smartphone use through the social control of health behavior theory. Background: Nighttime smartphone use is a behavioral risk factor for sleep problems. While previous research has predominantly focused on individual-level risks of sleep disturbances, the role of social context remains underexplored. Theoretical frameworks, specifically the Social Control of Health Behavior, suggest that social relationships regulate health-related behaviors; however, it is unclear how far this regulation extends to modern digital behaviors among couples. Method: We analyzed survey data from three waves of the SmartSleep Study (2018, 2020, and 2023; total N = 25,028), including a longitudinal follow-up subset (N = 1,003). We tested multivariate associations between living with a partner, changes in cohabitation status and frequent nighttime smartphone use by fitting generalized linear mixed-effects models. Additionally, we mapped the complex interplay between indicators of social integration, social support, smartphone use, and sleep quality using hierarchical clustering of non-linear correlations. Results: Cohabiting participants had lower odds of frequent nighttime smartphone use compared to those living alone (OR = 0.66; 95% CI: 0.61, 0.72). This lower risk was driven primarily by cohabitation with a partner (OR = 0.49; 95% CI: 0.36, 0.66). Longitudinal analysis supported these findings, showing that sustained cohabitation was associated with less frequent nighttime use (OR = 0.56; 95% CI: 0.38, 0.82). Clustering analysis revealed that indicators of social integration and support clustered with favorable sleep quality. Conclusion: Our findings suggest that the health-protective effects of cohabitation with a partner extend to digital behaviors. Consistent with social control of health behavior theory, the presence of a partner appears to reduce frequent nighttime smartphone use, highlighting the critical importance of considering social context when addressing digital health hygiene and promoting sleep.

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Perceived Social Support and Self-Efficacy as Mediators Between Health Literacy and Quality of Life Among Middle-Aged and Older Adults with Hypertension: A Cross-Sectional Study in Six Central Provinces of China

Zhao, Y.; Yun, Y.; Bai, T.; Xiong, L.; Ruan, Y.; Zhao, H.; Wang, W.; Wang, F.

2026-06-08 public and global health 10.64898/2026.06.06.26355051 medRxiv
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Abstract Objective: The onset of hypertension occurs at a younger age in China, and the relationship between health literacy and quality of life among middle-aged and older hypertensive patients remains unclear. This study explored whether perceived social support and self-efficacy mediate the association between health literacy and quality of life in middle-aged and older hypertensive patients. Methods: A questionnaire was administered to 1,015 middle-aged and older hypertensive adults from communities in six central provinces of China. The EQ-5D scale, Perceived Social Support (PSS) scale, Self-Efficacy Scale (SES), and Health Literacy Scale (HLS) were used to assess quality of life, social support, self-efficacy, and health literacy, respectively. Mplus 8.3 software was used to construct a structural equation model for path analysis. Results: The mean PSS, SES, HLS, EQ-5D, and EQ-VAS scores were 15.57{+/-}3.45, 10.61{+/-}2.41, 9.49{+/-}2.86, 0.88{+/-}0.18, and 71.06{+/-}17.49, respectively. Health literacy and quality of life scores significantly differed among middle-aged and older hypertensive patients, and both showed positive correlations with perceived social support and self-efficacy (both P<0.001). Perceived social support and self-efficacy exhibited a chain mediated effect on the relationship between health literacy and quality of life (EQ-5D utility index and EQ-VAS), accounting for 28.57% of the total effect of the EQ-5D utility index and 27.26% of that of the EQ-VAS. This study is the first to elucidate the mechanism by which health literacy influences quality of life in middle-aged and older hypertensive patients through the chain-mediated effect of perceived social support and self-efficacy. Conclusion : Health literacy is significantly correlated with quality of life in middle-aged and older hypertensive patients. This correlation can directly or indirectly explain the impact on quality of life through mediating pathways involving perceived social support and self-efficacy. Keywords: hypertensive patients, perceived social support, self-efficacy, health literacy, quality of life, mediating effect

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Gendered pathways to adolescent mental health: An empirical assessment of a new conceptual framework

Alaze, A.; Hagen, D.; Schamberger, T.; Razum, O.; Miani, C.

2026-06-10 epidemiology 10.64898/2026.06.09.26355310 medRxiv
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Introduction Gender norms and roles are important determinants of physical and mental health in the key period of adolescence. Yet, the gendered pathways to mental health in adolescents are not fully understood. Using a conceptual framework for global adolescent mental health that we developed based on a Delphi process, we empirically investigated the associations between six gender-related constructs and adolescent mental health. Methods We used cross-sectional Gender and Adolescence: Global Evidence (GAGE) data from Ethiopia (2020) to explore the associations between sex, gender norms, psychological competencies, gender attitudes, gender roles, with the latter two also serving as mediators, and psychological distress (GHQ-12), using Structural Equation Modelling (SEM). Results The SEM model contained measurements from 1,584 adolescents, including 843 girls and 741 boys, with a median age of 13 years. Out of 14 pathways tested, we found statistically significant associations between psychological competencies and psychological distress; sex and gender attitudes; and between gender norms and psychological competencies, gender attitudes, and gender roles. Hence, the gender-related constructs were mostly associated with each other, rather than with psychological distress. Conclusion The gender-related constructs are strongly interrelated, thereby attenuating their individual effects on psychological distress. The interplay of gender-related constructs should be considered when developing interventions to promote mental health in adolescents.

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Predictors of Road Safety behaviors among Boda-Boda Operators and their passengers in Kampala: A Mixed-Methods Study

Ainembabazi, R.; Kimuli, D.; Murami, T.; Wafula, S. T.; mgeyi, E.; Kwesiga, J. B.; Kibingo, P.; Mugumya, I.; Atulomah, N. O.; Nsubuga, D.

2026-06-07 public and global health 10.64898/2026.05.29.26354085 medRxiv
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Background Despite existing road safety regulations, commercial motorcycle riders commonly referred to as "Boda Bodas" in Uganda continue to experience high rates of injuries due to road traffic accidents resulting from unsafe riding behaviours, contributing significantly to morbidity and mortality among both riders and passengers. Safe riding behaviours are less well documented, as well as factors associated with the observance of those behaviours. This study aimed to determine factors associated with safe riding behaviors for both boda-boda riders and their passengers in Kampala Central Division. Methods A cross-sectional survey study design was conducted using a convergent parallel mixed-methods design guided by the PRECEDE model. Quantitative data were collected from 424 riders through structured questionnaires administered by trained research assistants. Binary Logistic regression was used to determine the independent predictors of safe road riding behaviors, and Adjusted Odds ratios (AORs) have been reported. Data were analyzed using descriptive and inferential statistics, with a p-value <0.05 considered statistically significant. Qualitative data were collected simultaneously with quantitative data through in-depth semi-structured interviews with 10 passengers to capture perceptions of rider behaviors and safety practices. Thematic analysis was applied, and results were triangulated to highlight convergences and divergences between quantitative and qualitative findings, providing a comprehensive understanding of safety determinants for both riders and passengers. Results Of the 424 riders (mean rider age was 29.56 {+/-} 5.71), overall, 276 (65.1%) of riders exhibited unsafe riding behaviors. In the bivariate analysis with Logistic regression, predisposing factors (education, marital status, religion, and willingness to obey traffic regulations), and reinforcing factors (family encouragement) were significantly associated with safe riding behaviors. However, in the adjusted model, secondary (AOR=0.50; 95% CI:0.30-0.85) and post-secondary education (AOR=0.57; 95% CI:0.33-0.98), being married (AOR=0.56; 95% CI:0.34-0.91), Christian religion (AOR=2.98; 95% CI:1.63-5.47), willingness to obey traffic regulations (AOR=0.41; 95% CI:0.24-0.70), union advocacy (AOR=1.76; 95% CI:1.03-3.01), and well-maintained roads (AOR=1.65; 95% CI:1.07-2.55) were significant predictors of safe riding behaviors. Qualitative interviews further highlighted barriers to safety, including a lack of helmets, over-speeding, disregard for traffic regulations, and poor road infrastructure. Conclusions Rider and passenger safety is still low, interdependent, and influenced by multiple factors. Integrated interventions focusing on education, stronger families, religious affiliations, union safety advocacy, and stricter enforcement of traffic regulations are vital for enhancing safety for both riders and passengers.

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Knowledge, attitudes and practices regarding risk factors for cardiovascular disease among women in an urban slum of Kathmandu, Nepal: A cross-sectional study.

Kasaju, M.; Shrestha, A. P.; Oli, N.; Vaidya, A.

2026-06-08 public and global health 10.64898/2026.06.04.26354909 medRxiv
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Introduction: Cardiovascular diseases (CVDs) are the leading cause for death and disability worldwide accounting for 75% of deaths in low- and middle-income countries (LMICs) like Nepal. Urbanization and globalization remains the major cause of rise in CVDs among urban poor population along with growth in slum settlements. This study aims to assess the knowledge, attitude and practice (KAP) of CVDs and its risk factors among women of one such urban poor community in Nepal. Methodology: This cross-sectional study (n=388) in the Sinamangal-Minbhawan slum area was conducted using semi structured questionnaire based on STEPs survey and HARDIC study among the participants selected through convenient sampling. Descriptive analysis was done using SPSS version 21 and KAP scores were further categorized based on median score to perform multivariate logistic analysis. Additionally, Anthropometric and blood pressure measurements were also recorded and analyzed. Results: The median age (Interquartile range) of participants was 33 years (17) with majority of them being Dalit by ethnicity, housewives, with up to primary level education belonging to upper lower socioeconomic class. More than half (53.3%) of the participants were obese and over 23% were hypertensive. While half of the hypertensive women were aware of their status, only 3% had their blood pressure under control.The median knowledge, attitude and practice (KAP) scores were 12, 60 and 10 respectively. The KAP scores were positively associated with socioeconomic status of the participants. Conclusion: The study revealed low knowledge with high prevalence of behavioral risk factors of CVDs along with high prevalence of other metabolic risk factors like high body mass index, high waist hip ratio and hypertension among women of slum area with a positive attitude to prevent CVDs and its risk factors.

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Usage Pattern and Associated Factors of Natural Mosquitoes Remedies in Endemic Communities of Borno State, Nigeria

Njapdze, R. K.; Ekerette, I. B.

2026-06-08 public and global health 10.64898/2026.06.04.25342216 medRxiv
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Introduction: Malaria, primarily transmitted by Anopheles mosquitoes, remains a major public health concern in Maiduguri, Borno State, Nigeria. While conventional control methods (e.g., ITNs) face challenges due to insecticide resistance and accessibility constraints, many communities rely on locally sourced natural products. This study aimed to assess the prevalence, usage patterns, and associated factors of these natural alternatives. Methods: A cross-sectional survey was conducted across three purposefully selected communities in Maiduguri (Mairi, Furi, Lagos Street). A total of 450 household heads were interviewed using a structured questionnaire, collecting data on socio-demographics, specific natural products used, method of application, frequency, and perceived efficacy. Data were analyzed using descriptive statistics and binary logistic regression. Results: Overall usage prevalence of natural products was high at 68.4%. The most common products identified were Neem (Azadirachta indica) extract (45.9%) and burnt Lemon Grass (Cymbopogon citratus) (31.2%). Usage pattern was predominantly indoor fumigation (burning), and over 70% of users prepared the products crudely at home. Logistic regression revealed that rural residence (Odds Ratio (OR): 2.1; p<0.01) and low education level (OR: 1.8; p<0.05) were significant independent predictors of higher natural product reliance. Conclusion: Natural products constitute a widely adopted, community-driven vector control method in Borno State. The high prevalence and association with vulnerable populations suggest an urgent need to standardize the preparation and application of these products for potential integration into regional malaria control programs. Keywords: Anopheles, Adulticides, Borno State, Malaria, Natural Repellents, Vector Control, Usage Pattern.

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Global Health Injustice From Climate Change Driven By Consumption

Rupcic, L.; Yoo, D.; Levasseur, A.; Alexandre, C.; Laurent, A.; Jolliet, O.

2026-06-12 public and global health 10.64898/2026.06.10.26355381 medRxiv
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Climate change imposes unequal health burdens from heat and cold, disproportionately harming vulnerable nations least responsible for emissions. A framework to quantitatively attribute this damage to different countries' consumption patterns has been missing. We developed a global framework linking consumption-based greenhouse gas emissions to country-specific health burdens, measured in Disability-Adjusted Life Years (DALYs). Our results quantify the profound scale of this externalized harm. For example, average North American consumption imposes a global health burden of 34 days of healthy life per person per year, without net damage suffered. In contrast, Sub-Saharan Africa endures 25 days per person per year despite minimal emissions. The resulting Health Injustice Index provides a powerful instrument for climate accountability, reframing responsibility in terms of tangible human health impacts.

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Malaria Risk among Internally Mobile Individuals and Heterogeneous Mobility Patterns in Two Hypoendemic Communities: Implications for Malaria Elimination in the Peruvian Amazon.

Ramirez Saavedra, R.; Acosta, C.; Rodriguez, P.; Cabrera-Sosa, L.; Escalente, A. A.; Vinetz, J. M.; Torres, K.; Gamboa, D.

2026-06-11 epidemiology 10.64898/2026.06.10.26355294 medRxiv
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Background: Human mobility is increasingly recognized as a key factor influencing malaria transmission dynamics, particularly in low-transmission settings approaching elimination. This study aimed to assess mobility patterns and their association with malaria risk in two hypoendemic communities in the Peruvian Amazon. Method: A longitudinal study was conducted in the communities of Libertad and Urcomirano (Mazan River basin). Monthly population screenings were combined with weekly active and passive case detection. A total of 678 individuals were enrolled. Mobility patterns were assessed through structured questionnaires, and social network analysis was used to characterize travel connections. Log-binomial regression analysis was applied to identify risk factors associated with malaria infection. Result: Internally, mobile individuals in Libertad showed a higher malaria incidence (>32.47 cases per 1,000 person-months) than those in Urcomirano (<10.15 cases per 1,000 person-months). Travel networks were mainly connected to Mazan district and Iquitos city, followed by local streams such as Armas and Arahuana. Mobility was primarily driven by family, administrative and occupational activities. Male sex (PR = 2.15, 95% CI: 1.37 - 3.37) and age [&ge;]15 years (PR = 1.98, 95% CI: 1.24 - 3.19) were significantly associated with malaria infection (p-value < 0.05). Conclusion: Internally mobile populations represent a key high-risk group sustaining malaria transmission in hypoendemic settings. Targeted interventions focusing on mobile individuals should be integrated into malaria elimination strategies in the Peruvian Amazon and similar endemic regions.

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Direct and mediated effects (DME) SLCMA: a novel method for life course modelling with time-varying covariates

Beer, S.; Simpkin, A. J.; Eldeeb, S. Y.; Zar, H. J.; Stein, D. J.; Dunn, E. C.; Smith, A. D. A. C.

2026-06-06 epidemiology 10.64898/2026.05.29.26354427 medRxiv
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Background: In prospective cohort studies, where an exposure is collected repeatedly, interest often lies in determining whether the timing of that exposure has a differential effect on a later outcome. The Structured Life Course Modeling Approach (SLCMA), where users select between temporal hypotheses of exposure specified a priori, provides one way to analyse such longitudinal data. However, few studies using SLCMA consider the effect of time-varying covariates (TVC) which may impact associations. Methods: We present a modified version of the SLCMA - called direct and mediated effects (DME)-SLCMA - which corrects for TVC. We first develop the DME-SLCMA method, test it through simulation, and apply it to psychosocial data from the Drakenstein Child Health Study (DCHS, n=336) to investigate relationships between maternal psychopathology, TVC of socioeconomic status, and offspring depressive symptoms. Results: We found that, on average, offspring depressive symptoms score increased by 3.9% (95% CI: 1.0%-6.9%, p = 0.039) for each unit of maternal psychopathology (SRQ) at 48 months whilst adjusting for time-varying socioeconomic status (at 18, 30, 42 and 54 months). Our simulations identified several realistic scenarios where selections ignoring TVC - with TVC mediated exposure effects present - were prone to be incorrect, including our DCHS example. Conclusion: DME-SLCMA is a robust new approach for life course modelling in the presence of time-varying covariates. We recommend adjusting for TVC whenever possible, and, when not possible, our simulation study identified that scenarios where mediated effects are comparable, or greater, in magnitude to direct effects are most prone to confounding.

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Wealth-Related Inequalities in Cesarean Section Utilization Among Facility-Based Births in Bangladesh: Evidence from Public and Private Healthcare Facilities

Mahmud, S.

2026-06-11 public and global health 10.64898/2026.06.09.26355308 medRxiv
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Background Bangladesh has experienced a rapid increase in cesarean section (CS) utilization over the past two decades. While previous studies have documented socioeconomic disparities in CS use, evidence on how wealth-related inequalities differ between public and private healthcare facilities remains limited. This study assessed the magnitude and drivers of socioeconomic inequality in CS utilization among facility-based births in Bangladesh. Methods We analyzed data from 3,008 facility-based births reported in the 2022 Bangladesh Demographic and Health Survey (BDHS). Survey-weighted multivariable logistic regression was used to identify factors associated with CS utilization. Wealth-related inequality was assessed using concentration curves and the Erreygers-corrected concentration index (ECCI). Regression-based decomposition of the standard concentration index was performed to quantify the contribution of socioeconomic, demographic, and healthcare-related factors to observed inequalities overall and separately for public and private facilities. Results Overall, 71.2% of facility-based births were delivered by CS, with substantially higher prevalence in private facilities (84.2%) than in public facilities (35.9%). Women delivering in private facilities had markedly higher odds of CS than those delivering in public facilities (adjusted odds ratio [AOR]: 9.07; 95% confidence interval [CI]: 7.17-11.47). Significant pro-rich inequality was observed overall (ECCI: 0.154; 95% CI: 0.117-0.191), with inequality substantially greater in public facilities (ECCI: 0.189; 95% CI: 0.114-0.264) than in private facilities (ECCI: 0.049; 95% CI: 0.014-0.084). Decomposition analysis showed that household wealth was the dominant contributor to inequality, particularly the richest wealth quintile, accounting for 81.5% of overall inequality, 63.8% in public facilities, and 109.7% in private facilities. Conclusions Wealth-related inequalities in CS utilization remain substantial in Bangladesh despite widespread use of the procedure. Although pro-rich inequality exists across both sectors, inequality is considerably greater in public facilities and is driven by different mechanisms across facility types. Policies should simultaneously improve equitable access to medically necessary CS and reduce unnecessary procedures, particularly within the private sector.

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Exploring emergency department attendance patterns during the UEFA European Football Championship 2024 in Germany

Charfeddine, N.; Schranz, M.; Schlump, C.; Rupprecht, M.; Ullrich, A.; Diercke, M.; AKTIN Research Group, ; Estupinan Mendez, J.

2026-06-09 epidemiology 10.64898/2026.06.08.26355151 medRxiv
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Background: Mass gathering events (MGEs) are associated with several public health challenges and may cause a strain on healthcare services. Literature findings on the impact of MGEs on emergency departments (EDs) are heterogeneous. Objectives: To examine shifts in ED attendance characteristics during a major sporting tournament, namely the UEFA European Football Championship 2024 held in Germany. Methods: We conducted a retrospective observational study using ED data from the Emergency Department Data Registry. We compared baseline ED attendance characteristics between the tournament and the reference period, defined as two weeks before and two weeks after the tournament, and between Germany game days and non-Germany game days. Hourly attendance patterns were analysed for all Germany games using a reference range. Results: We included data from 41 EDs, totalling 253,493 attendances during the study period. A 1.57% increase in attendance was observed during the tournament compared to the reference period, with baseline characteristics remaining similar. The median daily attendance within all EDs was slightly lower on Germany game days (4066) compared to non-Germany game days (4128). Modest changes were observed in the hourly attendance on Germany game days, most notable during the last Germany game where a decrease in attendance below the reference range extended over three hours. Conclusions: The observed shifts in ED attendance were minimal, suggesting that no major changes of public health relevance occurred in ED attendance during the tournament. We highlight the utility of using ED data for monitoring and for enhancing the understanding of the public health risks and challenges associated with MGEs.

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Stochastic Morphodynamics of the Human Aorta Across the Lifespan

Twohig, K. C.; Mansour, M.; Pugar, J. A.; Yuan, K.; Pocivavsek, L.; Klishin, A. A.

2026-06-08 surgery 10.64898/2026.06.05.26355015 medRxiv
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Biological systems evolve as continuous dynamical processes, but at organ-scale and across human lifespans they are rarely observed longitudinally--population data typically exist instead as sparse, cross-sectional snapshots. Inferring lifespan dynamics from such data requires methods distinct from those used at cellular and tissue scales where dense observations are accessible. We address this problem in the thoracic aorta, where surgical decisions currently rest on static, age- and sex-agnostic diameter thresholds that reduce three-dimensional morphology to a single scalar. Treating normal aortic morphology as a stochastic dynamical system, we pose a continuous-time drift-diffusion process in a two-coordinate state space of normalized surface area (A) and normalized fluctuation in integrated Gaussian curvature ({delta} K), and fit closed-form solutions of the Fokker-Planck equation by maximum likelihood to a sex-balanced, age-uniform cohort spanning infancy to age 99. Inter-individual variability is treated as a fitted diffusion parameter rather than as residual scatter, which is distinct from prior normative studies that report variability as scatter around a regression line. The framework identifies two growth regimes for aortic size (childhood expansion followed by persistent adult growth, with adult males growing approximately 70% faster than adult females) and a single dynamical regime for aortic shape, with heteroscedastic variability accumulating at a rate comparable to the mean drift over the lifespan. Applied to independent cohorts of acute and chronic thoracic aortic dissections, the multivariate model identifies over 95% as statistical outliers via Mahalanobis distance, consistently outperforming either coordinate alone. The same probabilistic envelope that describes normal aging thus defines a baseline against which disease can be detected, supporting a shift toward dynamic, age- and sex-aware assessment of thoracic aortic pathology.

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A Decade of the Center for Disease Control and Prevention's FluSight Influenza Forecasting

Hines, A. G.; Mathis, S. M.; Johansson, M. A.; Biggerstaff, M.; Reed, C.; Borchering, R.

2026-06-08 epidemiology 10.64898/2026.06.05.26354941 medRxiv
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Since the U.S. 2013/14 influenza season, the CDC's FluSight Challenge has provided a platform for evaluating influenza forecasting models and fostering collaboration across institutions. The Challenge aims to improve the science and enhance the utility of infectious disease forecasts for public health decision making. We analyzed ten years of submitted forecasts (2014/15-2019/20 (influenza-like illness seasons) and 2021/22-2024/25 (hospital admissions seasons)) across a range of model types, including statistical, mechanistic, machine learning, and hybrid models. Influenza-like illness (ILI) forecasts were evaluated using the exponentiated logarithmic score (skill metric) while hospital admissions forecasts were evaluated using the log transformed relative Weighted Interval Score. Corresponding potential performance differences were assessed using Wilcoxon rank-sum tests, and associations with team participation history were evaluated using Spearman's rank correlation. Model performance varied by season, and no single model type consistently outperformed others. In ILI seasons, statistical models generally performed better than mechanistic and machine learning models, though consistent differences were not observed in more recent hospital admissions seasons. Ensemble forecasts showed better overall performance across seasons, and the CDC's FluSight ensemble ranked among the top-performing forecasts every year. We also found a positive correlation between forecast accuracy and the number of years a team participated in the Challenge, with statistically significant associations in four seasons. These findings highlight the benefits of ensemble approaches and sustained engagement in improving forecasting performance, while also underscoring the continued value of forecast evaluation before and following the COVID-19 pandemic. Insights from the FluSight Challenge can guide future infectious disease forecasting efforts and support more effective public health preparedness.