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Epidemiology and Infection

Cambridge University Press (CUP)

Preprints posted in the last 7 days, ranked by how well they match Epidemiology and Infection's content profile, based on 84 papers previously published here. The average preprint has a 0.10% match score for this journal, so anything above that is already an above-average fit.

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Greater intergroup bias in vaccination attitudes among physicians than the general public

Murakami, M.; Ohtake, F.

2026-04-25 infectious diseases 10.64898/2026.04.23.26351641 medRxiv
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While vaccination conflicts have become apparent, physicians' attitudes toward those with differing views remain unclear. Through an online survey of 492 physicians and 5,252 members of the general public in Japan in February 2026, we investigated attitudes toward four vaccines (influenza, measles, HPV, and COVID-19). Intergroup bias was assessed as ingroup minus outgroup attitudes using a feeling thermometer. Multilevel regression examined associations with agreement group and physician status. Intergroup bias was significantly positive in both agreement and disagreement groups across all vaccine types, and was higher in the agreement group. Physicians exhibited higher intergroup bias than the general public. These findings indicate that vaccination conflict is bidirectional: physicians, often viewed as targets of hostility from vaccine-hesitant individuals, themselves exhibit greater intergroup bias toward those with opposing views. Interventions to raise physicians' awareness of their own bias, alongside communication strategies for vaccine-hesitant individuals, are needed.

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Tongue swab Xpert MTB/RIF Ultra testing for tuberculosis in adolescents: a cross-sectional study of diagnostic accuracy and acceptability

MacLean, E. L.; Ma, T. T.; Chuong, L. H.; Minh, K. H.; Hoddinott, G.; Pham, Y. N.; Tiep, H. T.; Nguyen, T.-A.; Fox, G.; Nguyen, N. T.

2026-04-25 infectious diseases 10.64898/2026.04.17.26351119 medRxiv
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Introduction Improved diagnostics are needed for people at risk of tuberculosis, especially adolescents. Tongue swab (TS) molecular testing has emerged as a promising strategy for tuberculosis diagnosis. We evaluated diagnostic accuracy and acceptability of Xpert MTB/RIF Ultra (Xpert) using TS samples for tuberculosis detection among adolescents. Methods We conducted a cross-sectional diagnostic accuracy study with consecutive recruitment in Vietnam. Adolescents aged 10-19 who were recommended to undergo investigation for tuberculosis and had not received tuberculosis treatment in the past years were eligible. Participants provided TS and sputum samples and completed a structured survey regarding sampling experiences. TS was tested on Xpert, with sputum tested on Xpert and liquid culture. We utilised a composite reference standard of a positive result on sputum Xpert or sputum culture to define disease status. Sensitivity, specificity, and diagnostic yield were calculated for TS Xpert. Results From July to December 2025, we enrolled 225 adolescents from Can Tho and An Giang provinces in southern Vietnam. Fewer than half (96/225, 43%) the participants exhibited a tuberculosis -like symptom, and the majority (157/225, 70%) were close contacts of a person recently diagnosed with tuberculosis. TS were collected from all adolescents, while 116 (52%) could provide mucopurulent sputum. Tuberculosis prevalence was relatively low (12/225, 5.3%). TS Xpert sensitivity (90% CI) and specificity (90% CI) were 58.3% (35.6, 78.0) and 99.5% (97.9, 99.9), respectively. Diagnostic yield among all diagnosed was 58.3% (7/12). TS sampling was highly acceptable to adolescents; the short time and simplicity of collecting TS were considered favourably. Conclusions The sensitivity and diagnostic yield of TS Xpert was relatively low among adolescents recommended for tuberculosis investigation, which includes asymptomatic individuals who may not provide high quality sputum. Specificity was excellent, and everyone could provide a TS. TS high acceptability indicates it remains a promising sample for diagnostic algorithms.

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Impact and cost of scaling up TB screening and diagnostics in Asias ten high-burden countries: a modelling analysis

Mandal, S.; Rade, K.; Singh, A.; Nair, S. A.; Sahu, S.

2026-04-19 infectious diseases 10.64898/2026.04.16.26351072 medRxiv
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Background Tuberculosis (TB) remains a critical public health challenge, with two-thirds of the global TB burden in ten Asian countries. Social vulnerabilities, comorbidities, health inequity, multi-dimensional poverty, malnutrition, and barriers to healthcare access continue to fuel TB epidemic. Inability to detect asymptomatic and sub-clinical TB, combined with passive approach in service delivery and overreliance on smear microscopy, leads to delayed diagnosis, a substantial burden of undetected cases, and continuing TB transmission in the communities. In such a context, the introduction and scale-up of active case-finding approaches - including community-based TB screening using highly sensitive screening tools and novel rapid diagnostics - becomes a strategic priority to interrupt transmission. The growing availability of multiple screening and diagnostic options makes evidence-based decision-making increasingly complex. Methods To estimate the potential epidemiological impact and cost implications of scaling up TB diagnostics and community-based screening in ten high-burden Asian countries, we constructed a mathematical model and evaluated multiple intervention scenarios. We then assessed and compared four service delivery models: 1) digital ultraportable chest x-ray (UPCXR) & Xpert/Truenat in community, 2) digital UPCXR in community and Xpert/Truenat at health facilities, 3) digital UPCXR in community and near point of care (nPOC) at health facilities, 4) nPOC in community & Xpert/Truenat at health facilities - for total investment required and projected health benefits for their cost-effectiveness. Results and conclusions The modelling study indicated that strengthening health facility capacity (with enhanced TB screening, expanded molecular diagnostics, reduced loss to follow-up, private sector standard of care, leading to increased treatment coverage & quality of active disease treatment and reduced post-treatment relapse, scale-up of TB preventive treatment (TPT), and provision of nutritional support to 80% of TB patients and their household contacts) can significantly reduce TB incidence and mortality; however, community-wide mass screening remains essential to achieving TB elimination targets . Targeted screening of vulnerable populations demonstrated greater cost-effectiveness than untargeted screening approaches. Achieving the End TB goals will ultimately require an effective TB vaccine with high population-level coverage. AI-enabled digital UPCXR-based screening combined with Xpert/Truenat testing at the community level demonstrated maximum epidemiological impact potential, while the most cost-efficient model is Digital UPCXR in the community combined with nPOC testing at health facilities. An investment of USD 12.7 billion over the next five years in community-level implementation of digital UPCXR and molecular diagnostics could avert an additional 9.8 million TB cases and 1.9 million deaths across ten Asian countries over a ten-year horizon.

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Implementation of SMS and voice message reminders to reduce childhood immunization dropout rate in urban settings: A Pilot Study in Lome-Togo in 2026

Badarou, S.; Attah, K. M.; Gounon, K. H.; Dali, A. S.; Sire, X. R.; Dia, E. C.

2026-04-20 public and global health 10.64898/2026.04.19.26350799 medRxiv
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ObjectiveThis study aimed to assess the effectiveness of SMS and voice message reminders in reducing the dropout rate in Lome-Togo, in 2026. MethodsWe conducted a cross-sectional study between October 2025 and March 2026 in the Grand Lome region. The intervention consisted of an integrated digital system used by health facilities to send automated SMS. Categorical variables were described in terms of frequency and proportion; Fishers exact test was used to compare proportions. Quantitative variables were described by their means accompanied by their standard deviation; the Wilcoxon rank-sum test was used to compare means. The significance level for statistical tests was set at 5%. ResultsA total of 30 health facilities were included. Seventy percent (70.0%) of the health facilities used messages associated with calls. Ninety percent (90.0%) of participants found the reminders useful, and 60.0% reported an improvement in Expanded Program on Immunization services related to their use. Among participants who received a reminder, 51.0% kept their vaccination appointments. The Penta 1/3 dropout rate decreased from 3.2% before the intervention to 1.3% (p < 0.001). Among the 323 parents of children included, only 20.74% reported receiving a reminder by phone. Sixty-point-five percent (60.5%) preferred to receive both text messages and voice calls. ConclusionThis study demonstrates the operational feasibility of an SMS/call-based reminder system in reducing dropout rate for childhood vaccination in Togo.

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Oropouche, Dengue, and Chikungunya differential diagnosis. Development and validation of predictive models with surveillance data from Espirito Santo-Brazil.

Nickel Valerio, E. C.; Coli Seidel, G. M.; Da Silva Nunes, R.; Alvarenga Americano do Brasil, P. E.

2026-04-25 infectious diseases 10.64898/2026.04.17.26350875 medRxiv
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There is an ongoing Oropouche Fever (OF) outbreak in Brazil since 2024. There are dengue and chikungunya prediction models available, but none to help discriminate dengue, chikungunya, and OF. Objective: This study aims to develop and validate clinical prediction models for dengue, chikungunya, OF. Methods: This study uses surveillance data from Espirito Santo state / Brazil, from 2023-2025. Epidemiological investigations and biological samples were used to conclude cases as either (a) clinical-epidemiologically confirmed, (b) laboratory confirmed, or (c) discarded. The predictors were all data related to signs, symptoms, and comorbidities available in the notification forms. The analysis was performed using random forest regression models, one for each outcome, in development and validation datasets. Results: A total of 465,280 observations were analyzed, 261,691 dengue cases (56.6%), 18,676 chikungunya cases (4.0%), 12,174 OF cases (2.6%), and 179,115 discarded cases (38.6%). All three models had good discrimination and moderate to good calibration after scaling prediction. The models retained from 26 to 16 predictors each. Leukopenia and vomiting were the most discriminatory predictors for dengue, arthritis, arthralgia, and rash were the most discriminatory for chikungunya, and epidemiological features were the most relevant for OF. The dengue, chikungunya, and OF models had ROC AUC of 0.726, 0.851, and 0.896 in the validation set, respectively. Conclusion: This research identified predictors most discriminative between dengue, chikungunya, and OF. We developed and validated predictive models, one for each condition, with moderate to very good performance available at https://pedrobrasil.shinyapps.io/INDWELL/. One may use them in diagnostic work-up and arbovirus surveillance.

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The evolving epidemiology of scrub typhus in Thailand (2003-2024): insights from latent process modelling of national surveillance data

Wongnak, P.; Chaisiri, K.; Perrone, C.; Chalvet-Monfray, K.; Areechokchai, D.; Pan-ngum, W.

2026-04-21 epidemiology 10.64898/2026.04.20.26351270 medRxiv
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BackgroundScrub typhus is a major yet neglected vector-borne disease in Thailand, where it has been nationally notifiable for over two decades. However, long-term changes in its epidemiology, including reporting rates, transmission intensity, disease severity, and seasonal patterns, have not been comprehensively characterised at the national level. MethodologyWe analysed 22 years of national surveillance data for scrub typhus in Thailand (2003-2024) using a latent process model that jointly fits reported cases with published nationwide seroprevalence data and antibody kinetics to estimate reporting rates and underlying transmission dynamics across all 77 provinces of Thailand. FindingsOver the 22-year study period, 143096 cases and 119 deaths were reported nationally. Estimated reporting proportion broadly mirrored transmission intensity, being higher in high-burden regions and lower elsewhere. A synchronous decline in detection was observed across all regions during the COVID-19 pandemic, followed by rapid rebound by 2024. After accounting for these reporting dynamics, the force of infection was highest in the northern provinces but also substantial in the northeast and south, with upward trends in some provinces. Susceptibility among older adults aged 65 and above increased progressively over the study period, reversing the pattern observed two decades earlier. Case-fatality in the 25-35-year reference group was low and declined from 0.14% (95% Credible Interval [CrI]: 0.06-0.29%) to 0.06% (95% CrI: 0.02-0.12%), but relative case-fatality remained consistently highest among adults above 65 across all periods. Three geographically distinct seasonal patterns were identified, all stable over time. ConclusionOver two decades, scrub typhus transmission in Thailand has been shown to extend well beyond its traditionally recognised northern focus, with substantial burden in previously underappreciated regions, while the demographic profile of those most affected has shifted progressively toward older adults. These findings support the need for regionally tailored surveillance, age-targeted clinical preparedness, and sustained investment in understanding the ecological drivers of transmission. Key messagesScrub typhus is a common but neglected cause of fever in Thailand, where it has been reported through the national surveillance system for over two decades. However, trends in reported cases can be misleading because they reflect not only true changes in transmission but also variation in diagnosis and reporting over time and across regions. We developed a model that combines surveillance data with seroprevalence surveys and antibody kinetics to separate true changes in transmission from variation in reporting, allowing us to estimate how transmission intensity, disease severity, and seasonal patterns have evolved from 2003 to 2024 across all 77 provinces. We found that substantial transmission occurs not only in the well-studied northern provinces but also in the northeast and south, where the disease has received less attention. Susceptibility has progressively shifted toward older adults, who also face the highest case-fatality, while three distinct seasonal patterns vary by region but have remained stable over time. These findings suggest that scrub typhus control in Thailand requires a shift from a predominantly northern focus toward regionally tailored strategies that account for local transmission timing, an ageing at-risk population, and the ecological drivers that sustain transmission in each setting.

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Episia: An Open-Source Python Library for Epidemiological Surveillance, Modeling, and Biostatistics in Resource-Limited Settings

Ouedraogo, F. A. S.

2026-04-20 epidemiology 10.64898/2026.04.17.26350337 medRxiv
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Despite the evolution of epidemiological analysis and modeling tools, difficulties still remain, especially in developing countries, regarding the availability and use of these tools. Often expensive, requiring high technical expertise, demanding constant connectivity of several or sometimes even significant resources, these tools, although efficient, present a major gap with the operational realities of health districts. It is in this context that we introduce Episia, an open-source Python library designed and conceived to provide a framework to facilitate epidemiological analysis and modeling. It integrates a suite of compartmental epidemic models (SIR, SEIR, SEIRD) with a sensitivity analysis using the Monte Carlo method, a complete biostatistics suite validated against the OpenEpi reference standard, as well as a native DHIS2 client for automated data ingestion. Developed in Burkina Faso, it is optimized and aims not only to address these health challenges encountered in Africa but also remains a versatile tool for global health informatics.

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Tracking and predicting the dynamics of HIV-1 epidemics in France using virus genomic data

Colliot, L.; Garrot, V.; Petit, P.; Zhukova, A.; Chaix, M.-L.; Mayer, L.; Alizon, S.

2026-04-24 epidemiology 10.64898/2026.04.21.26351380 medRxiv
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Understanding the dynamics of HIV epidemics is important to control them effectively. Classical methods that mainly rely on occurrence data are limited by the fact that an unknown part of the epidemic eludes sampling. Since the early 2000s, phylodynamic methods have enabled the estimation of key epidemiological parameters from virus genetic sequence data. These methods have the advantage of being less sensitive to partial sampling and to provide insights about epidemic history that even predates the first samples. In this study, we analysed 2,205 HIV sequences from the French ANRS PRIMO C06 cohort. We identified and were able to reconstruct the temporal dynamics of two large clades that represent the HIV-1 epidemics in the country. Using Bayesian phylodynamic inference models, we found that the first clade, from subtype B, originated in the end of 1970s, grew rapidly during the 80s before decreasing from 2000 to 2015 and stagnating since then. The second clade, from circulating recombinant form CRF02_AG, emerged and spread in the 80s, grew again in the early 2000s, before declining slightly. We also estimated key epidemiological parameters associated with each clade. Finally, using numerical simulations, we investigated prospective scenarios and assessed the possibility to meet the 2030 UNAIDS targets. This is one of the rare studies to analyse the HIV epidemic in France using molecular epidemiology methods. It highlights the value of routine HIV sequence data for studying past epidemic trends or designing public health policies.

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Epidemiological Patterns and Characteristics of Animal Bite Cases in Sylhet, Bangladesh: A Retrospective Study of 6,565 Cases

Hossain, H.; Mohiuddin, A. S. M.; Islam, S.; Insan, M.; Ahmed, S.; Brishty, K. A.; Parvej, M.; Yadav, S. K.; Ahmed, S.; Das, S. R.; Rahman, M. M.; Rahman, M. M.; Paul, B.

2026-04-22 public and global health 10.64898/2026.04.21.26351359 medRxiv
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BackgroundAnimal bites represent a significant public health concern due to the risk of injuries and transmission of zoonotic diseases such as Rabies, particularly in low and lower- middle-income countries (LMICs). Understanding the epidemiological characteristics of animal bite incidents is essential for improving the prevention and control strategies. This study aimed to characterize the epidemiological patterns and characteristics of animal bite cases in Sylhet, Bangladesh. Methodology/Principal findingsWe conducted a retrospective analysis of 6,565 animal bite cases reported between January 1 and December 31, 2024, in Sylhet, Bangladesh. Data on demographic characteristics, type of biting animal, site of bite, and exposure category were collected and analyzed to determine associations using correlation analyses and chi-square tests. Among the victims, 3,917 (60%) were male and 2,648 (40%) were female and young adults aged 20-39 years comprised the largest group (39% of cases). The majority of cases (88.1%) originated from urban areas within Sylhet City Corporation. Cats were the leading cause of bites (56.6%), followed by dogs (35.0%) and monkeys (7.5%), suggesting a shift from the traditional dog-dominated pattern. The most frequently affected anatomical sites were the legs (50.3%) and hands (40.9%). Most exposures were classified as World Health Organization (WHO) Category II (98.2%). Bite incidents showed moderate seasonal variation, with peaks in spring and early autumn. A significant declining temporal trend was observed for monkey bites (R = -0.59, p = 0.044), whereas cat and dog bite patterns remained relatively stable throughout the year. Significant associations were identified between bite site and age group, as well as between biting animal and demographic characteristics (p < 0.05). Conclusion/SignificanceThese findings highlight the epidemiological patterns of animal bites in Sylhet and emphasize the need for strengthened public awareness, surveillance, and preventive strategies to reduce animal bite incidents and associated zoonotic disease risks. SynnopsisO_LIA large-scale retrospective analysis of 6,565 animal bite cases revealed a cat-dominant bite pattern (56.6%), contrasting with the traditional dog-dominant paradigm in South Asia. C_LIO_LIYoung adults (20-39 years) and males (60%) were disproportionately affected, reflecting occupational and behavioral exposure risks. C_LIO_LIUrban residents (88.1%) accounted for the majority of cases, highlighting the growing public health burden of animal bites in rapidly urbanizing settings. C_LIO_LIThe most frequently affected anatomical sites were the legs (50.3%) and hands (40.9%). Bite incidents showed moderate seasonal variation, with peaks in spring and early autumn. C_LIO_LICategory II exposures (98.2%) predominated, indicating a high burden of seemingly minor injuries that may be underestimated in rabies prevention strategies. C_LI

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Mediation analysis in longitudinal data: an unbiased estimator for cumulative indirect effect

Li, Y.; Cabral, H.; Tripodis, Y.; Ma, J.; Levy, D.; Joehanes, R.; Liu, C.; Lee, J.

2026-04-20 epidemiology 10.64898/2026.04.18.26351189 medRxiv
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Mediation analysis quantifies how an exposure affects an outcome through an intermediate variable. We extend mediation analysis to capture the cumulative effects of longitudinal predictors on longitudinal outcomes. Our proposed model examines how mediators transmit the effects of the current and previous exposure on the current outcome. We construct a least-squared estimator for cumulative indirect effect (CIE) and used three approaches (exact form, delta method, and bootstrap procedure) to estimate its standard error (SE). The estimator of CIE is unbiased with no unmeasured confounding and independent model errors between mediator model and outcome model at all time points, as shown in statistical inference and in simulations. While three SE estimates are numerically similar, bootstrap procedure is recommended due to its simplicity in implementation. We apply this method to Framingham Heart Study offspring cohort to assess if DNA methylation mediates the association of alcohol consumption with systolic blood pressure over two time points. We identify two CpGs (cg05130679 and cg05465916) as mediators and construct a composite DNA methylation score from 11 CpGs, which mediates for 39% of the cumulative effect. In conclusion, we propose an unbiased estimator for CIE. Future studies will investigate the missingness in mediators and outcomes.

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Factors influencing repeated decisions to decline cervical cancer screening among women living with HIV in Jos, Nigeria: a qualitative study

Abubakar, A.; Inuwa, S. M.; Ali, M. J.; Abdullahi, K. M.; Doe, A.; Ngaybe, M. G. B.; Madhivanan, P.; Musa, J.

2026-04-23 public and global health 10.64898/2026.04.22.26351475 medRxiv
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Women living with HIV face about a six-fold higher risk of cervical cancer, yet screening uptake remains low in many sub-Saharan African settings. We explored factors influencing repeated decisions to decline cervical cancer screening during routine HIV care among women living with HIV at a large HIV clinic in Jos, Nigeria. Between September and December 2024, we conducted an exploratory qualitative study at the AIDS Prevention Initiative in Nigeria Clinic in Jos, Nigeria. We purposively recruited 27 women living with HIV aged 21 to 65 years who had never undergone cervical cancer screening and had repeatedly declined screening offers during routine HIV care, including at the current clinic visit. Semi-structured in-depth interviews were conducted in English or Hausa, audio-recorded, transcribed verbatim, and translated into English where needed. Data were analyzed thematically using theory-informed coding based on the Health Belief Model and Social Ecological Model. Among 27 women living with HIV who had repeatedly declined screening, perceived susceptibility was often low or uncertain despite recognition of cervical cancer severity. Perceived benefits were acknowledged but were frequently outweighed by overlapping barriers, including knowledge gaps and misinformation, indirect and downstream costs, emotional barriers, logistical constraints, clinic-flow and service-delivery barriers, and anticipated stigma. Education, reminders, and supportive clinic processes acted as cues to action, and most participants expressed willingness to screen in future. Among women living with HIV at this clinic who repeatedly declined screening when it was offered, perceived benefits were often outweighed by multilevel barriers. Screening programs may integrate fear-reduction and stigma-sensitive counseling with practical service delivery improvements, including shorter waiting times, reduced indirect costs, predictable and streamlined clinic flow, and consistent provider invitations and reminders, while addressing misinformation through community-embedded, culturally tailored messaging. These strategies may improve screening uptake and support more equitable cervical cancer prevention for women living with HIV in similar HIV-care settings.

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Genetic diversity and antimicrobial susceptibility pattern of Shiga toxin-producing Escherichia coli and Campylobacter spp. isolated from healthy goats in southern Thailand

Wiriyaprom, R.; Ngasaman, R.; Kaewnoi, D.; Prachantasena, S.

2026-04-20 microbiology 10.64898/2026.04.18.719346 medRxiv
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Foodborne illness is a significant public health concern worldwide. Shiga toxin-producing Escherichia coli and Campylobacter species are recognized as important zoonotic bacterial pathogens contributing to human infections through the food chain, particularly via foods of animal origin. Although goat meat is in high demand in the southern region of Thailand, studies on foodborne pathogens in this livestock species remain limited. The current study aimed to (i) determine the antimicrobial susceptibility of Campylobacter spp. and STEC isolated from goats, and (ii) analyze the genetic relationships among Campylobacter spp. And E. coli O157 isolates obtained from different sources. Campylobacter jejuni and C. coli isolates were characterized based on sequences of seven housekeeping genes using the Achtman multilocus sequence typing scheme. For E. coli O157:H7, core genome multilocus sequence typing analysis was performed using whole-genome sequencing data. Genetic diversity was observed among C. jejuni, whereas a clonal population structure was detected in C. coli and E. coli O157:H7. Overlapping genetic characteristics were observed between C. jejuni isolates from goats and those previously reported in livestock and humans in Thailand. Among Campylobacter species, resistance to fluoroquinolones, including ciprofloxacin and nalidixic acid, was observed, whereas resistance to fosfomycin was most frequently detected in Shiga toxin-producing E. coli. Tetracycline-resistant isolates were identified in both Campylobacter species and Shiga toxin-producing E. coli at moderate levels. A multidrug-resistant pattern was observed only in C. coli, whereas no multidrug-resistant C. jejuni or Shiga toxin-producing E. coli isolates were detected. These findings indicate that healthy goats may serve as potential reservoirs of zoonotic pathogens and antimicrobial resistance in southern Thailand, where goat meat is frequently consumed.

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Modeling the impact of adherence to U.S. isolation and masking guidance on SARS-CoV-2 transmission in office workplaces in 2021-2022

Garcia Quesada, M.; Wallrafen-Sam, K.; Kiti, M. C.; Ahmed, F.; Aguolu, O. G.; Ahmed, N.; Omer, S. B.; Lopman, B. A.; Jenness, S. M.

2026-04-21 epidemiology 10.64898/2026.04.14.26350639 medRxiv
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Non-pharmaceutical interventions (NPIs) have been important for controlling SARS-CoV-2 transmission, particularly before and during initial vaccine rollout. During the pandemic, the US Centers for Disease Control and Prevention issued isolation and masking guidance in case of COVID-19-like illness, a positive SARS-CoV-2 test, or known exposure to SARS-CoV-2. However, the impact of this guidance on mitigating transmission in office workplaces is unclear. We used a network-based mathematical model to estimate the impact of this guidance on SARS-CoV-2 transmission among office workers and their communities. The model represented social contacts in the home, office, and community. We used data from the CorporateMix study to parametrize social contacts among office workers and calibrated the model to represent the COVID-19 epidemic in Georgia, USA from January 2021 through August 2022. In the reference scenario (58% adherence to guidance among office workers and the broader population), workplace transmission accounted for a small fraction of total infections. Reducing adherence among office workers to 0% increased workplace transmissions by 27.1% and increasing adherence to 75% reduced workplace transmission by 7.0%. Increasing adherence to 75% among office workers had minimal impact on symptomatic cases and deaths; increasing it among the broader population was more effective in reducing office worker cases and deaths. In our model, moderate adherence to recommended NPIs in workplaces was effective in reducing transmission, but increasing adherence had limited benefit given workplaces that have low contact intensity and hybrid work arrangements. These results underscore the public health benefits of community-wide adoption of recommended NPIs.

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Demystifying Clone-Censor-Weight Method in Target Trial Emulation: A Real-World Study of HPV Vaccination Strategies

Lin, T.; Li, Y.; Huang, Z.; Gui, T. T.; Wang, W.; Guo, Y.

2026-04-22 health informatics 10.64898/2026.04.21.26351413 medRxiv
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Target trial emulation (TTE) offers a principled way to estimate treatment effects using real-world observational data, but analyses of time-varying treatment strategies remain vulnerable to immortal time bias. The clone-censor-weight (CCW) approach is increasingly used to address this problem, yet key aspects of its causal interpretation and implementation remain unclear. In this work, we emulate a target trial using electronic health records (EHRs) to compare completion of a 3-dose 9-valent human papillomavirus vaccination (HPV) series within 12 months versus remaining partially vaccinated among vaccine initiators. We link CCW to the classic potential outcome framework in causal inference, evaluate the role of different weighting mechanisms, and account for within-subject correlation induced by cloning using cluster-robust variance estimation. Our study provides practical guidance for applying CCW in real-world comparative effectiveness studies to address immortal time bias and supports more rigorous and interpretable treatment effect estimation in TTE.

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ICU admission and mortality in adult patients with influenza A/H1N1-related pneumonia in Vietnam since the 2009 H1N1 pandemic: a 10-year cohort study

Ho, M. Q.; Duong, T. B.; Nguyen, T. L. N.; Tri, N. S.; Bui, T.; Thai, T. T.; Muscatello, D. J.; Sunjaya, A. J.; Chen, S.; Nguyen, N. T.; Nguyen, T. M.; Nguyen, A. T. K.; Duong, C. M.

2026-04-20 infectious diseases 10.64898/2026.04.18.26351156 medRxiv
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The A(H1N1)pdm09 virus remains a major global health threat. This study examined the burden of ICU admission, mortality, and associated predictors among patients with A(H1N1)pdm09 pneumonia in a leading center for infectious diseases in Vietnam. Information on demographic, clinical, and laboratory characteristics, and outcomes was retrieved from medical records of adults admitted with influenza A(H1N1)pdm09 during 2009-2019. Among 729 cases, 21.7% (158/729) developed pneumonia. Among 158 pneumonia cases, 36.7% (58/158) developed moderate-to-severe acute respiratory distress syndrome (ARDS), and 15.2% (24/158) received invasive ventilation. ICU admission and mortality rates were 48.7% (77/158, 95%CI 41.1-56.5%) and 8.2% (13/158, 95%CI 4.9-13.6%), respectively. Predictors of ICU admission included being >60 years old (adjusted OR [AOR] 13.864, 95%CI 2.185-87.956, P=0.005), comorbidities (AOR 6.527, 95%CI 1.710-24.915, P=0.006), AST (AOR 1.013, 95%CI 1.001-1.025, P=0.029), and moderate-to-severe ARDS (AOR 14.027, 95%CI 4.220-46.627, P<0.001). Predictors of mortality were invasive ventilation (AOR 55.355, 95%CI 1.486-2062.375, P=0.030) and double-dose oseltamivir or combination therapy (AOR 32.625, 95%CI 1.594-667.661, P=0.024). In conclusion, mortality is not rare in A(H1N1)pdm09 infection. Monitoring of older patients and those with comorbidities, liver enzyme elevation, or moderate-to-severe ARDS is essential for the timely detection of complications requiring intensive care.

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Determinants of Skilled Birth Attendance in Nigeria: A Population-Based Analysis of the 2018 Demographic and Health Survey

Unegbu, U. L.

2026-04-23 epidemiology 10.64898/2026.04.23.26350432 medRxiv
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Background: Nigeria bears one of the highest maternal mortality burdens globally, with skilled birth attendance (SBA) remaining critically low in many regions. Understanding the independent determinants of SBA is essential for designing targeted interventions. Methods: This cross sectional study analyzed 21,465 births from the 2018 Nigeria Demographic and Health Survey (NDHS), a nationally representative household survey using stratified two stage cluster sampling. SBA was defined as delivery attended by a doctor, nurse, midwife, or auxiliary midwife. Multivariable logistic regression was used to estimate adjusted odds ratios (aOR) with 95% confidence intervals for the associations between SBA and maternal education, household wealth, place of residence, geopolitical region, maternal age, parity, and antenatal care (ANC) utilization, after accounting for confounding. Results: The overall prevalence of SBA was 44.9%. In the fully adjusted model, higher education (aOR = 7.01, 95% CI: 5.68-8.67), richest wealth quintile (aOR = 6.27, 95% CI: 5.27-7.46), and attending [&ge;]4 ANC visits (aOR = 3.80, 95% CI: 3.51-4.11) were the strongest independent predictors of SBA. Regional inequalities were pronounced, with SBA prevalence ranging from 17.7% in the North West to 85.6% in the South West. Crude effect estimates for education and wealth were substantially attenuated after adjustment, indicating large confounding by correlated socioeconomic factors. Conclusions: Maternal education, household wealth, ANC utilization, and geopolitical region are independent determinants of SBA in Nigeria. Scaling up ANC programs represents the most immediately actionable intervention, while long term gains require investment in girls' education and wealth equity. Targeted strategies for the northern regions are urgently needed. Keywords: skilled birth attendance, maternal mortality, Nigeria, DHS, antenatal care, logistic regression, health equity

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Assessing the efficacy of behaviourally informed invitation messaging in increasing attendance at the NHS Targeted Lung Health Check: A randomised experimental study

Tan, X.; Danka, M. N.; Urbanski, S.; Kitsawat, P.; McElvaney, T. J.; Jundi, S.; Porter, L.; Gericke, C.

2026-04-24 public and global health 10.64898/2026.04.12.26350693 medRxiv
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Background: Lung cancer screening can reduce lung cancer mortality through early detection, but uptake of the NHS Targeted Lung Health Check (TLHC) programme remains low. Behaviourally informed invitation messages have been proposed as a low-cost approach to increase attendance, but evidence of their effectiveness in lung cancer screening is mixed. Few intervention studies used evidence-based behaviour change frameworks, and rarely tailored invitation strategies to empirically identified barriers and enablers. Methods: In an online experiment, 3,274 adults aged 55-74 years and with a history of smoking were randomised to see one of four behaviourally informed invitation messages or a control message. Participants then rated their intention to attend a TLHC appointment, and selected barriers and enablers to attending from a pre-defined list, which were classified according to the Theoretical Domains Framework. Invitation messages were mapped to Behaviour Change Techniques using the Theory and Techniques Tool. Message conditions were compared on intention to attend TLHC using bootstrapped ANOVA followed by pairwise comparisons. Exploratory counterfactual mediation analyses examined the role of fear in intention to attend. Results: Behaviourally informed invitation messages did not meaningfully increase intention to attend TLHC compared with the control message. While a GP-endorsed message showed a small potential benefit relative to the other conditions, this finding was not robust after adjustment for multiple comparisons. Participants most frequently reported barriers related to Emotion (particularly fear), Social Influence, and Knowledge, while Beliefs about Consequences emerged as the primary enabler of attendance. Only around half of reported barriers and enablers were addressed by the invitation messages. Exploratory analyses found that fear was associated with lower intention to attend a TLHC appointment, yet none of the behaviourally informed messages appeared to reduce fear compared to the control message. Conclusions: Improving lung cancer screening uptake will likely require invitation messages that directly address emotional concerns, particularly fear, alongside credible recommendations. These findings highlight the importance of systematically aligning invitation message content with empirically identified behavioural influences when designing scalable interventions to improve lung cancer screening uptake.

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Differences in tuberculosis prevalence among people living with and without HIV in low-and-middle-income countries: A systematic review and meta-analysis

Swartwood, N.; Can, M. H.; Mortazavi, S. A.; Cui, H.; Singh, N.; Ryuk, D. K.; Horton, K.; MacPherson, P.; Menzies, N. A.

2026-04-22 infectious diseases 10.64898/2026.04.20.26351343 medRxiv
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BackgroundTuberculosis (TB) and human immunodeficiency virus (HIV) are leading causes of infectious disease deaths, with disproportionate impact in low- and middle-income countries (LMICs). Despite well-established biological relationships between these diseases, there is limited information on how TB prevalence differs between people living with and without HIV. MethodsWe conducted a systematic review and meta-analysis of TB prevalence surveys conducted in LMICs and published during January 1st 1993-October 13th 2025 (PROSPERO CRD42024503853). We extracted bacteriologically-confirmed TB prevalence estimates stratified by participant HIV status. Surveys that offered HIV testing to all, sputum-collection-eligible, or TB-positive participants were included in the primary analysis. We applied Bayesian meta-regression to estimate pooled risk ratios (RR) of bacteriologically-confirmed TB prevalence among participants living with versus without HIV. Additionally, we estimated country-level and overall TB notification-to-prevalence (N:P) ratios by HIV status. FindingsOf 10,211 potentially relevant publications, 12 TB prevalence surveys--representing 264,530 participants within nine countries in Southern and Eastern Africa--were used in the primary analysis. Reported TB prevalence was higher among participants living with versus without HIV in 11/12 surveys, with an overall pooled RR of 3{middle dot}86 (95% credible interval: 2{middle dot}41-5{middle dot}53). N:P ratios were higher among participants living with HIV in all examined countries. The overall pooled N:P ratios were 1{middle dot}74 (0{middle dot}59-4{middle dot}56) and 0{middle dot}48 (0{middle dot}17-1{middle dot}20) among participants living with versus without HIV, respectively. InterpretationIn Southern and Eastern Africa, bacteriologically-confirmed TB prevalence is three- to six-times higher among people living with HIV. Comparison of prevalence and notification data suggest higher rates of TB diagnosis for people living with versus without HIV, but also indicates substantial delays in the detection of untreated TB cases for both populations. FundingWellcome Trust, UK National Institute for Health and Care Research, UK Foreign, Commonwealth and Development Office, NIH. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSThere is limited systematic evidence on how the prevalence of TB disease differs between people living with HIV and without HIV. Multiple observational cohorts have described substantially elevated TB incidence among populations with HIV, but disease prevalence will also be affected by differences in mortality and treatment uptake rates. We searched PubMed from inception through January 21, 2026 using the search string ((HIV AND TB) OR HIV/TB) AND (prevalence AND (systematic review OR meta-analysis)) without any restrictions on language. We also reviewed investigators personal libraries. This search yielded 506 publications; however few of these included prevalence data. An analysis conducted in 2020 synthesized HIV status-stratified data from seven national TB prevalence surveys in Africa and found that HIV prevalence was lower among prevalent TB cases than among notified cases. This study did not include subnational surveys and did not distinguish between survey participants with self-reported or test-confirmed HIV status. Added value of this studyThis study synthesized TB prevalence data, stratified by participant HIV status, from national and subnational surveys conducted in LMICs and published between January 1st 1993 and October 13th, 2025. Collated data represented 681,402 survey participants across ten countries. All but one study were conducted in Southern and Eastern Africa. We limited our primary analysis to surveys that systematically tested participants for HIV and bacteriologically-confirmed TB. The prevalence of bacteriologically-confirmed TB was estimated to be three to six times higher than among people living with versus without HIV. Ratios of TB notifications to TB prevalence were higher for people living with HIV compared to people without HIV, suggesting higher rates of TB case detection (and likely shorter duration of disease) for people living with HIV and untreated TB than those without HIV. Implications of all available evidenceFew estimates of community-representative TB prevalence stratified by participant HIV status exist. These surveys have been concentrated in Southern and Eastern Africa, despite TB-HIV burden being distributed globally. Our findings highlight the elevated burden of TB among people living with HIV in these settings, as well as the limited data on the intersection of TB and HIV epidemiology in other world regions. Furthermore, our comparison of notification and prevalence data demonstrate substantial shortfalls in TB case detection, regardless of an individuals HIV status.

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Factors Associated with Malaria Vaccine Hesitancy Among Caregivers of Children 6-59 Months, In Ugenya Sub County, Siaya County, Kenya: A cross - Sectional Mixed Study

Ochieng', E. A.; Muita, J. W.; Olewe, T.

2026-04-23 public and global health 10.64898/2026.04.21.26351425 medRxiv
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ABSTRACT Background: Malaria remains a leading public health burden in sub-Saharan Africa, disproportionately affecting children under five years. In response, Kenya introduced the RTS,S/AS01 malaria vaccine in selected regions, including Siaya County where malaria transmission is endemic. Despite this milestone, uptake has been inconsistent, with hesitancy emerging as a significant barrier. Objective: This study aimed to determine factors associated with malaria vaccine hesitancy among caregivers of children 6-59 months in Ugenya Subcounty, Siaya County. Methodology: A cross-sectional mixed methods design was employed involving 425 caregivers and 15 healthcare workers and County health officials between January to February 2025. Quantitative data were collected using structured questionnaires and analyzed in Stata version 17 through descriptive statistics, bivariate analysis at 20% significance threshold, and multivariable logistic regression at 5% level to determine key factors associated with malaria vaccine hesitancy. Qualitative data from 15 key informant interviews were transcribed verbatim and thematically analyzed using NVivo. Thematic analysis, guided by a predefined codebook, was used to identify recurring patterns and extract key themes, which were illustrated with direct quotations from participants Results: Overall, 42.9% of caregivers (n=181; 95% CI: 38.9%-47.3%) reported hesitancy. Significant predictors included caregiver age, marital status, family size, access to health facilities, and vaccine availability. Single caregivers, those from smaller households, and those facing health facility access challenges were more likely to be hesitant to malaria vaccine. Despite high levels of knowledge, misconceptions and misinformation about vaccine safety, often spread via social media persisted. Conversely, caregivers relying on healthcare workers and mainstream media showed greater acceptance of malaria vaccine. Conclusion and Recommendations: Malaria vaccine hesitancy remains significant at 42.9%, driven by demographic factors such as younger age, single status, and smaller household size. Structural barriers including limited vaccine availability and poor access to health facilities further contribute to reluctance. Although knowledge and awareness were high, misinformation, particularly from social media, persisted, while information from healthcare workers improved acceptance. Addressing these gaps through targeted community engagement, improved access, and trusted communication channels is essential to increase uptake of malaria vaccine.

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Prevalence and Risk Factors of Respiratory Tract Infections Following Medically-Attended-Diarrhea in Children Aged 6-35 Months: Enterics for Global Health (EFGH)-Shigella Surveillance Study, 2022-2024.

Conteh, B.; Galagan, S. R.; Badji, H.; Secka, O.; Bar, B. T.; Rao, S. I.; Atlas, H.; Omore, R.; Ochieng, J. B.; Tapia, M.; Cornick, J.; Cunliffe, N.; Zegarra Paredes, L. F.; Colston, J.; Islam, M. T.; Mosharraf, M. P.; Qamar, F. N.; Fatima, I.; Pavlinac, P. B.; Hossain, M. J.

2026-04-20 infectious diseases 10.64898/2026.04.17.26351078 medRxiv
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Globally, respiratory tract infections (RTI) are the main cause of morbidity, and in Low-middle-income countries (LMICs) RTI including pneumonia are a leading cause of morbidity and mortality in children <5 years. Diarrheal illness increases RTI risk in young children through micronutrient depletion, and immune stress, yet data on post-diarrhea RTI burden in LMICs are limited. We determined the prevalence and risk factors of RTI within three months following medically-attended diarrhea (MAD) in children aged 6-35 months enrolled in seven EFGH country sites in Asia, Africa and South America. The EFGH study prospectively enrolled children aged 6-35 months with MAD in selected health facilities during a 24-month period from 2022 to 2024 and followed them for three months. RTI was defined as cough or difficulty breathing and the presence of one of the following symptoms at any scheduled or unscheduled visit during follow-up: stridor; fast-breathing; oxygen saturation <90%; or chest indrawing. The period prevalence and 95% confidence intervals of RTI were calculated, and correlates of RTI were assessed using modified-Poisson regression. From June 2022 to August 2024, 9,476 children aged 6-35 months presenting with MAD in the EFGH study sites were screened: 9,116 (96.2%) included in the current study. Nearly half were female (46.7%), and median age was 15 months. Overall, 48.5% received all age-appropriate vaccines, and 87.6% received the pneumococcal vaccine, with significant variation across countries. Nearly one-quarter of children were stunted, 17.2% wasted, and 21.9% underweight. RTI occurred in 3.8% of children during the three-month follow-up, mostly within the first month. Higher prevalence of RTI occurred among children aged 12-23 months (8.7%), those undernourished (16.1%), unvaccinated (4.0%) or living in poor sanitation settings (4.1%). While children who received all age-appropriate or pneumococcal vaccinations had a lower crude prevalence of RTI, these associations were not statistically significant after adjusting for age, sex and study site. RTI was infrequently observed in the three months following MAD presentation, with significant variability by site and with the highest prevalence in Malawi. RTI risk was highest in 12-23-month-olds and among children with undernutrition, and those living in poor sanitation conditions.