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Travel Medicine and Infectious Disease

○ Elsevier BV

Preprints posted in the last 30 days, ranked by how well they match Travel Medicine and Infectious Disease's content profile, based on 14 papers previously published here. The average preprint has a 0.01% match score for this journal, so anything above that is already an above-average fit.

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Cost-effectiveness of a package to ensure safe prescription of 7-day high-dose primaquine for the radical cure of Plasmodium vivax in Indonesia

Abraham, P.; Fransisca, L.; Adella, J.; Rahmalia, A.; Jimanto, V.; Angeline, S.; Putri, A.; Mannion, K.; Sakalidis, V.; Sutanto, I.; Pasaribu, A. P.; Poespoprodjo, J. R.; Simpson, J. A.; Price, R. N.; Devine, A.

2026-09-25 health economics 10.64898/2026.09.23.26363845 medRxiv
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The radical cure of Plasmodium vivax requires treatment of the dormant liver stages with either primaquine or tafenoquine but is constrained by the risk of severe hemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. A revised case-management package, New Primaquine Treatment (NPT), was designed to support safe radical cure in Indonesia, and included G6PD screening, targeting high dose primaquine and early clinical review. A decision-tree model was constructed using individual-level data from a study, that treated patients with 7mg/kg primaquine according to their G6PD activity: primaquine administered over 7 days (G6PD normal individuals), 14 days (individuals with intermediate G6PD deficiency), or 8 weeks (if severely G6PD deficient). The model incorporated costs, adverse events, and P. vivax recurrence over a six-month time horizon. A business-as-usual comparator was created using historical P. vivax recurrence data for Indonesia overall and the three provinces separately. The primary outcome was disability-adjusted life-years (DALYs) averted. Costs were analyzed from health system and societal perspectives, and incremental cost-effectiveness ratios (ICERs) were compared with Indonesias Health Technology Assessment recommended willingness-to-pay thresholds of 1 and 3 gross domestic product per capita (US$4,925 and $14,475). One-way and probabilistic sensitivity analyses were conducted to assess uncertainty. Overall NPT averted 0.0011 DALYs per patient with an incremental cost of US$7.40 per patient from a health system perspective. This resulted in an ICER of US$6,636 per DALY averted, which was not cost-effective at the $4,925 threshold. Cost-effectiveness varied across settings: from US$5,098 per DALY averted in Papua to US$20,051 per DALY averted in southern Sumatra and US$80,825 per DALY averted in northern Sumatra. The ICER reduced when the societal perspective was included, with NPT cost-effective in Indonesia overall ($2,261/DALY averted) and in Papua ($675/DALY averted). The risk of P. vivax recurrence and intervention costs were the most influential parameters on the ICER. Overall, NPT was between the 1-3x GDP per capita cost-effectiveness thresholds in Indonesia; however, cost-effectiveness varied significantly across settings, indicating that NPT may not be an optimal use of resources in areas with low incidence.

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Stage-Specific Associations of Automated RPR With Treponema pallidum qPCR Positivity and Cycle Threshold in Early Symptomatic Syphilis: A Multicenter Study Using Specimens Collected During Routine Care

Kasamatsu, A.; Ohama, Y.; Tomo, Y.; Imai, K.; Nakayama, S.-i.; Omori, R.; Yamagishi, T.; Yasuda, M.; Akeda, Y.

2026-10-15 infectious diseases 10.64898/2026.10.14.26365521 medRxiv
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Background: Treponema pallidum quantitative polymerase chain reaction (qPCR) positivity and cycle threshold (Ct) by rapid plasma reagin (RPR), disease stage, and other characteristics are poorly characterized in routine-care specimens, leaving it unclear when qPCR of such specimens is informative for diagnosis. Methods: This Japanese multicenter cross-sectional study explored qPCR positivity and Ct by these characteristics. Nonblood specimens collected during routine care underwent qPCR at a central laboratory for this study. Bayesian logistic and normal regressions modeled positivity and mean Ct of TP0574 and polA with stage-specific continuous automated RPR terms, patient characteristics, collection site, and facility random intercepts. Estimates were standardized over the analyzed specimens. Population-group predictions were instead averaged within each group. Results: Among 154 nonblood specimens from 145 patients (71.7% non-MSM men and women) at 14 facilities, 109 (70.8%) were qPCR positive. At RPR 1, adjusted positivity was 72.2% (95% credible interval, 60.9%--82.9%) in primary and 43.8% (16.7%--69.9%) in secondary syphilis. Positivity showed a modest downward trend with RPR in primary but increased in secondary syphilis, reflecting a stage-by-RPR interaction (secondary-to-primary ratio of odds ratios, 1.78; 1.25--2.65). Predicted positivity showed an upward trend with RPR values among MSM; adjusted positivity was relatively high for genital/urethral/urinary and anal/perianal/rectal specimens. Adjusted mean Ct increased with RPR in primary and followed an inverted-U pattern in secondary syphilis. Conclusions: In primary syphilis, nonblood qPCR positivity was high even at low RPR. When serologic findings remain inconclusive in this stage, qPCR is highly recommended for securing an early diagnosis.

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Genitourinary Brucellosis in an Endemic Region: Clinical Spectrum, Diagnostic Pitfalls and Treatment Outcomes of a 13-Year Retrospective Cohort

Savas, L.; Pekok, A. U.; Pekok, B. S.; Eser, Z. S.

2026-09-24 infectious diseases 10.64898/2026.09.22.26363646 medRxiv
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Aim: Brucellosis remains endemic throughout the Mediterranean basin, the Middle East and Central Asia. Genitourinary involvement is an uncommon but clinically consequential focal complication that closely mimics urological emergencies and may precipitate unnecessary surgery. Contemporary data describing its frequency, laboratory signature and treatment outcomes in endemic settings remain limited. Material-Methods: We retrospectively screened all adults ([≥]18 years) with confirmed brucellosis managed at a tertiary infectious diseases unit between January 2008 and December 2020. Genitourinary involvement was defined as epididymo-orchitis, orchitis, epididymitis and/or brucellar pyelonephritis. Clinical, laboratory, ultrasonographic, therapeutic and outcome variables were abstracted using a standardised form. Proportions are reported with Wilson score 95% confidence intervals (CI). Reporting followed the STROBE statement. Result: Genitourinary involvement was identified in 18 of 125 patients with brucellosis (14.4%; 95% CI 9.3-21.6); 16 (88.9%) were men and the mean age was 35.2 years (range 22-62). Scrotal disease dominated the male presentation: epididymo-orchitis in 10 of 16 men (62.5%; 95% CI 38.6-81.5), orchitis in 4 (25.0%) and epididymitis in 2 (12.5%). Both women presented with pyelonephritis, one of whom developed a tubo-ovarian abscess requiring drainage. Constitutional features were near-universal (fatigue 100%, night sweats 88.9%, fever 77.8%). Leukocyte counts remained within the reference interval in every patient (mean 5,680/mm3), whereas erythrocyte sedimentation rate (mean 32 mm/h) and C-reactive protein (mean 24.2 mg/L) were only mildly to moderately raised. The Coombs anti-Brucella test was positive in 18 of 18 patients (100%) and the standard agglutination test in 17 of 18 (94.4%), whereas blood culture yielded Brucella melitensis in only 1 of 18 (5.6%). Concomitant extragenitourinary focal disease was present in 8 patients. All patients received doxycycline plus rifampicin; none required modification of the regimen or orchiectomy, and no treatment failure occurred (0 of 18; 95% CI 0-17.6). Median follow-up was 12 weeks (range 6-52) and no relapse was documented within this interval. Conclusions: In endemic regions, genitourinary brucellosis should be suspected in any patient with acute scrotal or flank symptoms accompanied by constitutional complaints, even when the leukocyte count is normal and acute-phase reactants are only marginally elevated. Coombs anti-Brucella serology rather than blood culture is the diagnostic cornerstone, and prompt doxycycline-rifampicin therapy averts surgical intervention.

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Epidemiological patterns and factors associated with mortality among diphtheria cases in Kano State, Nigeria (2022-2025): A retrospective cohort study

Wekunda, P. W.; Ogunbode, O.; Okunromade, O.

2026-09-25 public and global health 10.64898/2026.09.22.26363747 medRxiv
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Introduction: Nigeria continues to report one of the highest burdens of diphtheria globally, with Kano State accounting for a disproportionate share of cases and deaths. Understanding epidemiological patterns and mortality determinants is essential for guiding targeted interventions. Objectives: To describe the distribution of diphtheria cases in Kano State by socio-demographic and clinical characteristics, Local Government Area, and month of reporting, and identify independent predictors of mortality. Methods: We conducted a retrospective cohort study of 21,369 patients with clinically compatible and laboratory-confirmed diphtheria using secondary data from medical records (2022-2025). Descriptive statistics summarized patient characteristics and disease distribution. Associations with mortality were assessed using chi-square or Fishers exact tests. Multivariable logistic regression identified predictors of mortality, reported as adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Results: Of 21,369 patients, 13,557 (63%) were female, with a median age of 11 years (IQR: 7-13.6). Children aged 5-9 years accounted for 29% of cases. Prior contact with a case was reported in 2,633 (12%) patients, while 168 (1%) were laboratory-confirmed. Overall, 13,468 (63%) patients were unvaccinated and 5,381 (25%) fully vaccinated; Diphtheria antitoxin DAT was administered to 2,035 (10%). Cases occurred in all local government areas (LGAs), with four accounting for 60% of cases. Transmission occurred year-round, peaking in March 2024 and August 2023 and 2025. Overall, 1,131 deaths occurred (CFR: 5.3%). Compared with patients aged [≥]20 years, younger age groups had higher odds of mortality: 0-4 years (aOR = 26.74, 95% CI: 17.64-42.72), 5-9 years (aOR = 19.77, 95% CI: 13.17-31.33), 10-14 years (aOR = 8.21, 95% CI: 5.41-13.13), and 15-19 years (aOR = 2.46, 95% CI: 1.45-4.26). Prior contact with a case was associated with lower odds of mortality (aOR = 0.42, 95% CI: 0.30-0.55), whereas laboratory confirmation (aOR = 2.33, 95% CI: 1.48-3.56) and DAT receipt (aOR = 2.55, 95% CI: 2.19-2.96) were associated with higher odds. Prior vaccination was associated with lower odds of mortality among fully vaccinated (aOR = 0.52, 95% CI: 0.44-0.61) and partially vaccinated patients (aOR = 0.61, 95% CI: 0.47-0.80). Conclusions and recommendations: During the study period, diphtheria was more common among younger children, females, and the unvaccinated. Although concentrated in a few LGAs, transmission was widespread and varied seasonally. Mortality was associated with younger age, laboratory-confirmed infection, and use of diphtheria antitoxin, whereas vaccination and prior contact were protective. Reducing the burden requires sustained efforts to strengthen routine immunization, implement targeted vaccination campaigns, ensure early detection and prompt treatment, and improve contact tracing and case management.

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Factors Associated with Divergent Introgression Outcomes from Wolbachia-Based Interventions in Rio de Janeiro, Brazil

Nelson, E.; Carcamo, P. M.; Ribeiro dos Santos, G.; Sylvestre Ribeiro, G.; Rodrigues da Costa, T.; Ilaria Dorigatti, I.; Salje, H.; Moreira, L. A.; Cummings, D. A. T.; Ko, A. I.

2026-10-21 infectious diseases 10.64898/2026.10.16.26365711 medRxiv
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Wolbachia-based interventions were less effective in achieving introgression in Rio de Janeiro than other settings. Reduced introgression occurred in locations where dengue was historically high, raising concerns of inequity. We examined factors affecting Wolbachia introgression in Rio through trajectory modeling, spatiotemporal Bayesian models, and Ae. aegypti abundance estimation. During the intervention (2017-2020), Wolbachia introgression was 26% (median; IQR,14-44%), with four distinct trajectories. Despite receiving more releases, densely populated areas with low socioeconomic status had lower introgression. In spatiotemporally explicit multivariable regressions, higher Ae. aegypti abundance, temperature, population density and lower socioeconomic status were associated with reduced introgression. Improved characterization of Ae. aegypti abundance and other structural/environmental predictors of introgression could be used to calibrate release doses to ensure equitable benefits from Wolbachia interventions.

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Nipah vaccine and monoclonal antibody introduction: Understanding endemic and at-risk country perspectives to inform demand forecasting

Dinkel, K. A.; Ruisch, A.; Mathur, I.; Bowe, R. T.; Windus, P.; Nonvignon, J.; Walker, D. G.; Torkelson, A. A.

2026-09-23 public and global health 10.64898/2026.09.21.26363632 medRxiv
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BackgroundNipah virus (NiV) is a zoonotic pathogen in the Henipavirus genus that causes severe, often fatal disease in humans. The World Health Organization and the Coalition for Epidemic Preparedness Innovations (CEPI) have designated NiV as a priority pathogen with pandemic potential. While CEPI is funding research on medical countermeasures, including vaccines and monoclonal antibodies (mAbs), there remains limited understanding of how at-risk countries will use them. This study aims to address this gap through targeted interviews and demand forecasting for 10 countries: Australia, Bangladesh, Cambodia, India, Indonesia, Malaysia, the Philippines, Singapore, Thailand, and Vietnam. Methodology/Principal FindingsInterviews with country and global stakeholders gathered data on regional sentiment, financing, and affordability. Profiles were developed to summarize each countrys perceived outbreak risk and their likely use of countermeasures. Demand was estimated by integrating these perspectives into models of likely country-level responses to three NiV outbreak scenarios: Expected, Amplified, and Extended. In the Expected scenario, countries focused on reactive use with global annual demand ranging from approximately 800 to 5,000 doses for vaccine-only, mAb-only, and combination interventions. Ring strategies were preferred given outbreak size and infrequency. Demand was highest for vaccine-only and combination interventions, with lower demand for mAbs-only due to affordability concerns and less familiarity in Bangladesh and India. In Amplified and Extended scenarios, countries expanded their responses to include preventive campaigns for healthcare workers and rural populations. These campaigns would require approximately 410,000 and 6,300,000 doses, respectively, if introduced in all 10 countries. Conclusions/SignificanceThis study has revealed existing sentiments regarding Nipah disease and interventions and modeled demand across three outbreak scenarios. Given global annual demand based on current epidemiology, Nipah countermeasure markets are unlikely to be commercially viable solely on routine country-financed demand. Instead, market health will require external financing and stockpile mechanisms to maintain demand between sporadic outbreaks. Author SummaryNipah virus (NiV), which causes severe and often fatal disease in humans, is recognized by the Coalition for Epidemic Preparedness Innovations (CEPI) as a priority pathogen with pandemic potential. In response, CEPI has supported the development of vaccines and monoclonal antibodies (mAb). However, limited evidence exists on how at-risk countries will deploy these medical countermeasures. We interviewed key decision-makers across 10 at-risk countries, along with global experts on NiV, to better understand disease prioritization, financing and affordability considerations, and countermeasure preferences. Interview findings informed the development of a demand forecast in response to Nipah outbreaks of varying intensity. At expected outbreak levels, countries focused their response on reactive strategies given outbreak size and infrequency. As outbreaks grew in size, countries considered expanding their response to include preventive campaigns targeting healthcare workers and at-risk, rural populations. This study provides new insights into country-level perspectives on NiV and medical countermeasures and quantifies expected demand across three outbreak scenarios and 10 countries. Our findings can provide a foundation for the strategic development of an international Nipah countermeasure stockpile, designed to address episodic NiV outbreaks and enhance pandemic preparedness.

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Interpreting changes in reported case fatality in endemic zoonoses: an analytical framework and ecological analysis of Lassa fever surveillance in Nigeria, 2017-26

Simons, D.

2026-10-15 infectious diseases 10.64898/2026.10.14.26365510 medRxiv
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Background. Nigeria's reported Lassa fever case fatality ratio (CFR) rose from 18.9% at week 23 of 2025 to 25.0% in 2026, prompting concerns over failing clinical care. Because surveillance artefacts can also alter CFRs, candidate mechanisms that published data can resolve were identified and evaluated. Methods. This ecological study extracted weekly state-level counts from 474 Nigeria Centre for Disease Control and Prevention situation reports (2017-2026). Per a pre-specified plan, years were compared at phase-matched points, year-on-year CFR changes were decomposed into within-state and between-state components, and tipping-point ascertainment shifts calculated. Weekly incident and cumulative published totals were compared post hoc. Findings. Of 11 candidate mechanisms, 2 could be evaluated fully and 5 in part. On weekly incident counts, 2026 did not differ from 2025 at the phase-matched midpoint (+0.3 percentage points, 95% CI -5.0 to 7.6); within-state (-1.1, 95% CI -4.7 to 3.0) and between-state (+0.5, -2.0 to 2.9) components spanned zero. Conversely, the published cumulative CFR was 5.4 to 6.2 percentage points higher because 70 deaths were added retrospectively by week 36 outside weekly reports. Reconciling cumulative figures would require 279 missed survivors (6% of suspected cases not confirmed). Interpretation. The 2026 CFR rise came from deaths added to cumulative totals outside the weekly counts, and published data cannot attribute it to care. Endemic zoonotic CFRs cannot serve as clinical outcome measures unless testing volumes, deaths added late, and post-mortem sampling are published alongside case counts. Funding. US NSF-NIH-NIFA EEID; UK BBSRC; Birgitta Sintring Fellowship (Uppsala University).

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A Growing Burden, a Persistent Gap: Cannabinoid Hyperemesis Syndrome Education and Emergency Department Trends in Michigans Legal Cannabis Market

Lorbeer, E. R.; Bronson, N.; Burgard, L. A.; Engle, M. E.; Randhawa, D. S.; Sotiroff, P. V.; Walker, H. R.; Zhu, H.; Mastenbrook, J. D.

2026-10-14 public and global health 10.64898/2026.10.09.26365113 medRxiv
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Background: Since Michigan's legalization of recreational adult-use cannabis in December 2018, health care providers in the city of Kalamazoo, Michigan, have informally observed an increase in cannabinoid hyperemesis syndrome (CHS) presentations, although the extent of this increase has not been formally characterized locally. CHS is frequently underrecognized and misdiagnosed, often resulting in repeated emergency department (ED) visits and substantial diagnostic costs before a diagnosis is reached. Despite this clinical and financial burden, it is unclear whether consumers are adequately informed of this risk through point-of-sale or public health resources. Methods: A cross-sectional environmental scan was conducted to identify publicly available educational content about CHS on the websites of licensed cannabis retailers in Kalamazoo and relevant public health agencies. Provisioning centers and public health websites were screened using a structured coding rubric developed specifically for the environmental scan to assess the presence, depth, web page placement, and intended audience of CHS-related content. Additionally, the electronic medical records at a local teaching hospital in Kalamazoo were queried to identify ED visits with a primary diagnosis of CHS from January 1, 2010 to December 31, 2025. Results: Before the legalization of marijuana, the hospital recorded six ED encounters with the primary diagnosis of CHS between January 2010 and November 2018, and 274 ED encounters between December 2018 and December 2025 (mean age: 29 years; 157 females, 123 males). The incidence rate of CHS-related ED encounters was 57.2 times higher during the post-legalization period than during the pre-legalization period (95% CI, 26.0-157.3; exact Poisson rate-ratio test, p < 0.0001). Among the licensed Kalamazoo provisioning centers reviewed, only one mentioned CHS as a warning but did not describe symptoms or offer medical guidance. CHS content was not identified on the websites of the state or local health departments. Conclusion: Despite the growing clinical concern regarding CHS, consumer-facing educational resources remain scarce. Although this study cannot establish a causal relationship between the availability of CHS-related educational content and the observed increase in ED encounters following legalization, it identifies a substantial lack of CHS-specific warnings in the evaluated consumer-facing resources. Given the clinical and potential economic burden associated with delayed CHS recognition, we recommend that Michigans existing point-of-sale pamphlet requirement be amended to include CHS-specific warning language.

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Assessing Knowledge and Risk Perception of Mosquitoes and Mosquito-Borne Viruses Among Medical Students in Cyprus: A Cross-Sectional MosquitoWise Study

Dali, A. M.; Vujicic, A.; Gato, D.; Volkan, E.

2026-10-19 medical education 10.64898/2026.10.15.26365696 medRxiv
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Abstract Background: Cyprus has transitioned into a high-alert zone for mosquito-borne viruses. This necessitates a proactive assessment of its future physicians. Following the 2022 re-establishment of Aedes aegypti in Larnaca and Aedes albopictus in Limassol, Cyprus, the island is now biologically primed for local outbreaks of dengue, Zika, and chikungunya, alongside Culex-borne West Nile virus. The study assessed medical students' knowledge and risk perception. Methods: A cross-sectional online survey administered the validated MosquitoWise Health Belief Model instrument to undergraduate-entry and graduate-entry students at a university in Cyprus in mid-2026. Results: Of 1023 students, 119 responded (11.6%), with pre-clinical students overrepresented (p<0.001). Mean knowledge was 5.43/9, stronger on mosquito biology (72.5%) than virus knowledge (54.2%). Median severity was 6.00/7 against susceptibility 4.25/7. Knowledge differed by study stage (p<0.001), correlated with severity (rs = 0.399) but not susceptibility. Conclusions: The study establishes a critical baseline for pre-clinical medical students in Cyprus. Overall, participants performed better on mosquito biology when compared to mosquito-borne viruses and how they spread. Our findings highlight the value of integrating theoretical microbiology with clinical practice in medical education to enhance physicians' preparedness for the changing landscape of newly emerging infections in Cyprus and across Europe as a whole. Key Words: Arboviruses, Cross-Sectional Studies, Cyprus, Health Belief Model, Medical Students, Risk Perception.

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Hepatitis E Virus Prevalence and Associated Risk Factors in Pregnant Women Attending Antenatal Consultations Niger Republic, 2025

Hassane, F.; Lagare, A.; Yacouba, A.; Ousmane, H.; Issa, M.; Magagi, L. H.; Aoula, B.; Kaka, B. K.; Diallo, O.; Djedenam, M.; DOUTCHI, M.; Mamadou, S.

2026-10-07 infectious diseases 10.64898/2026.10.05.26364823 medRxiv
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Background: Hepatitis E virus (HEV) is highly endemic in several African countries with high mortality rate among pregnant women. The prevalence of HEV in Niger among pregnant women is unknown. We hereby aim to report the prevalence and risk factors of HEV among pregnant women in Niamey, Niger. Methods: Blood samples were collected from pregnant women attending antenatal consultation in three selected Health centers in Niamey. Data were collected for socio demographic characteristics using a structured questionnaire. Samples were tested using ELISA and qRT-PCR for anti- HEV IgM and RNA detection respectively. HEV associated risk factors were determined using multivariate logistic regression models. Results: A total of 491 pregnant women were enrolled with mean age of 26.5 years. The prevalence of anti-HEV IgM antibodies was 17.1%, while HEV RNA was detected in 3.46% of participants, indicating recent and active HEV infection. Anti-HEV IgM seropositivity was more frequent among women aged 26-30 years and those in the third trimester of pregnancy. Gravidity was significantly associated with HEV RNA positivity (p = 0.032). In multivariable analysis, the use of well water was independently associated with HEV infection (aOR = 75.70; 95% CI: 1.23-4643.20; p = 0.039). Conclusion: In view of the high seroprevalence of HEV among pregnant women, preventive measures including hygiene sensitization should be prioritized. Further studies should be conducted to assess the real impact of HEV infection on maternal and fetal health.

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Quantifying the current and future risk of West Nile virus and Usutu virus in humans and horses across England and Wales using an R0-based suitability metric

de Klerk, J. N.; Pilgrim, J.; Baylis, M.; Blagrove, M.; Medlock, J. M.; Vaux, A. G. C.; Bruce, R. C.; Folly, A. J.; Sedda, L.

2026-10-06 infectious diseases 10.64898/2026.10.04.26364722 medRxiv
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In England and Wales, Usutu virus (USUV) was detected in 2020 and is now established. West Nile virus (WNV) has so far only been detected in a single location, in two Aedes vexans mosquito pools sampled during 2023 surveillance. Given the growing threat to the UK from Culex-borne viruses there is a need to undertake risk assessments to contribute to preparedness and surveillance strategy for both viruses across human and animal health sectors. Here, we present the first application of a mechanistic R0-based model, incorporating temperature dependence and combining data on vector species distribution with projected future climate scenarios, to assess transmission suitability for WNV and USUV across England and Wales. Under current climate conditions, the two viruses showed comparable spatial patterns, with risk concentrated most heavily in the southeast along the Thames estuary and extending into Kent, Essex and Surrey, as well as around Cambridgeshire and adjacent counties, and across Yorkshire, Nottinghamshire and Lincolnshire. This pattern broadly corresponded with the cumulative distribution of Culex mosquito abundance established in our earlier work (Culex pipiens pipiens, Culex pipiens molestus and Culex torrentium). Both viruses were projected to show increasing transmission suitability risk over time, with substantially steeper increases under Representative Common Pathway (RCP) 8.5 then RCP 4.5. Equine WNV cases were predicted to be most likely in southeast England, in particular around Newmarket, driven by the region's dense horse population. Among the human population, London was identified as the highest-risk area, with Liverpool and Manchester also showing elevated risk levels, driven by a combination of high human and mosquito distributions. When human population distributions were age-adjusted to account for the proportion of over 60 years-olds, there was elevated risk in coastal regions, particularly in the east (Norfolk and Suffolk) and southeast (Kent) of England. The geographic distribution of positive mosquito and bird USUV cases recorded in 2023 and 2024 broadly overlapped with areas predicted to have higher USUV suitability, providing validation for the model's spatial outputs. By characterising relative spatial transmission suitability risk, this work adds to a growing understanding of where arbovirus emergence and spread are most likely across England and Wales, and can support decisions around resource allocation, targeted surveillance efforts, and public health readiness. The results also underscore the importance of incorporating climate change and vector ecology into future modelling work, given their likely influence on how arbovirus risk evolves over time.

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National incidence of coccidioidomycosis in the United States estimated through machine learning integration of epidemiological, veterinary, and socioecological data

Couper, L. I.; Camponuri, S. K.; Sykes, J. E.; Li, X.; Hubbard, A. E.; Bustamante, B. L. M.; Williamson, T.; Ruberto, I.; Sondermeyer-Cooksey, G.; Karmarkar, E. N.; Yu, A. T.; Heaney, A. K.; Head, J. R.; Remais, J. V.

2026-10-16 epidemiology 10.64898/2026.10.14.26365564 medRxiv
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Importance: Coccidioidomycosis, also known as Valley fever, is a serious fungal disease caused by inhaling Coccidioides spores aerosolized from the soil. Despite rising public health concern, the distribution and incidence of coccidioidomycosis in the US remain poorly characterized as not all states are required to report cases, and case under-ascertainment is presumed to be high, particularly outside of the endemic region. Objective: To estimate monthly, county-level coccidioidomycosis incidence across the US while accounting for widespread under-ascertainment. Design, Setting, and Participants: We integrated multisource data, including human cases diagnosed in electronic health records, serological testing of dogs, and ecological and sociodemographic predictors, in a machine learning model estimating monthly, county-level coccidioidomycosis incidence. The model was trained on surveillance data from Arizona and California from 2013 to 2023, then applied to predict incidence in states across the contiguous US over the same time period. Main Outcomes and Measures: Incidence of coccidioidomycosis at the monthly county level. Results: The model predicted coccidioidomycosis incidence from 2013 to 2023 for 3,108 counties from all states in the contiguous US. The model identified 60 counties in non-reporting states where predicted incidence was [&ge;]2 cases per 100,000 population (considered moderate to high incidence). In states with mandatory reporting outside of Arizona and California, the model predicted county-level incidence rates that were 28% higher (95% bootstrap interval, 0.1%-69.8%) than those captured in national surveillance, equating to a total of 608 potentially missed cases per year (95% bootstrap interval, 340-964). Conclusions and Relevance: In this cross-sectional study, the model quantified case under-ascertainment for coccidioidomycosis relative to Arizona and California, and highlighted the potential for alternative data sources to fill in gaps in mandatory reporting. Estimating incidence while accounting for under-ascertainment and non-reporting may help efforts to improve public and physician awareness and to detect emergence in new regions.

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Community Knowledge And Attitude Towards Polio Immunization In Northern Nigeria

Muhammad, A. G.; Abar, I. O.; Sule, H.; Olim, A. N.

2026-09-29 public and global health 10.64898/2026.09.29.26364257 medRxiv
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ABSTRACT Background: Poliomyelitis remains a major public health concern where population immunity is incomplete and circulating vaccine-derived poliovirus (cVDPV) persists. Although Nigeria interrupted wild poliovirus (WPV) transmission in 2020, cVDPV cases continue to pose challenges, particularly in parts of northern Nigeria. Modern control strategies require a synergy of routine immunization, supplementary campaigns, disease surveillance, and community trust. Methods: This multicentre descriptive cross-sectional study evaluated community knowledge and attitudes towards polio immunization across 37 Local Government Areas (LGAs) in 20 states and the Federal Capital Territory (FCT). A multistage sampling strategy was utilized to select 1,850 adult respondents (50 per LGA) spanning rural, semi-urban, and urban settlements. Results: Overall, 40.4% (n = 747) of respondents demonstrated good knowledge, while 58.4% (n = 1,080) displayed positive attitudes towards polio immunization. A striking disparity was observed across residence classifications: respondents in urban/semi-urban LGAs exhibited significantly higher levels of good knowledge (51.7%, 569/1,100) compared to those in rural LGAs (23.7%, 178/750; {chi} = 144.00, df = 1, p < 0.001). Main sources of information were Questionnaire responses (53.6%) and community and Traditional leaders(17.2%). Conclusion & Recommendations: Substantial knowledge deficits persist in rural northern Nigerian communities despite generally favorable attitudes. Interventions must prioritize localized risk communication, involvement of traditional/religious leaders, strengthening routine primary healthcare integration, and targeting zero-dose children in hard-to-reach areas. Keywords: Poliomyelitis, Oral Polio Vaccine, Vaccine Hesitancy, Northern Nigeria, Community Health, Routine Immunization.

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Mapping county-level tick-borne disease risk in Illinois by integrating vector abundance, pathogen prevalence, and phenology

Hussain, A.; Bhowmick, S.; Mateus-Pinilla, N.; Smith, R. L.

2026-10-16 epidemiology 10.64898/2026.10.14.26365569 medRxiv
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Tick-borne disease risk reflects the combined influence of vector abundance, pathogen prevalence, human exposure, and seasonal activity, yet these components are rarely integrated at the county level. We developed species-specific ecological risk scores for three medically important tick species (Acari: Ixodidae): Amblyomma americanum (L.), Dermacentor variabilis (Say), and Ixodes scapularis Say, across all 102 Illinois counties using data from 2019 to 2022. County-level predicted tick abundance and pathogen prevalence were scaled and combined using equal weights to generate primary vector-level risk scores. Robustness to the equal-weight assumption was evaluated by systematically varying the relative weights assigned to abundance and pathogen prevalence, while a separate sensitivity analysis incorporated reported tick-bite incidence where available. Associations with human disease were evaluated using negative binomial regression of tick-borne disease case counts on the corresponding risk scores, with county population included as an offset. Monthly phenology indicators were constructed by integrating human disease cases, reported tick bites, and sampled tick abundance and were evaluated in relation to temperature and precipitation. Seasonal risk was estimated by combining county-level vector risk with species-specific monthly phenology, generating monthly risk surfaces that were deployed through an interactive R Shiny application. Higher risk scores were significantly associated with greater disease case rates for each tick species. County rankings were highly stable under moderate changes in abundance and prevalence weighting. Seasonal activity differed among species, with A. americanum and D. variabilis showing concentrated warm-season risk and I. scapularis exhibiting a broader seasonal profile. These county-level seasonal risk maps identify where and when relative tick-borne disease risk is elevated in Illinois, supporting targeted prevention, surveillance, and clinical awareness.

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Human Infection with Avian Influenza A(H7N7) Virus, Taiwan, 2026

Li, Y.-T.; Lin, Y.-T.; Chen, B.-S.; Kuo, C.-Y.; Huang, H.-Y.; Ko, H.-Y.; Huang, P.-Y.; Smith, G. J.; Lin, Y.-L.; Liu, M.-T.

2026-10-11 infectious diseases 10.64898/2026.10.09.26365013 medRxiv
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Low pathogenic avian influenza A(H7N7) virus detected in a poultry worker in Taiwan, 2026 was related to viruses circulating in Asian wild birds and possessed PB2 E627K, a mammalian adaptation marker. Enhanced surveillance for H7 viruses in poultry and rapid characterization of human cases are essential to assess pandemic potential.

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The impact of COVID-19 vaccination on long COVID prevention in the Omicron era: An updated systematic review and meta-analysis

Marjenberg, Z.; Peluso, M. J.; Wynberg, E.; Abduljawad, S.

2026-10-13 infectious diseases 10.64898/2026.10.12.26365288 medRxiv
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Objectives To evaluate the impact of COVID-19 vaccination on the prevention of long COVID (LC) in the Omicron era through an updated systematic review and meta-analysis. Methods We performed an update of our previously published systematic review and meta-analysis of vaccination and LC risk (searches between 1 January 2022 and 1 March 2024). Databases (Embase, MEDLINE, PubMed, Europe PMC, LILACS, Cochrane COVID-19 Study Register) were searched for studies published between 1 March 2024 and 13 July 2026. Observational studies assessing the impact of vaccination on the risk of LC four or more weeks after SARS-CoV-2 infection were included. Vaccines were restricted to those centrally authorised in the European Union. Random-effects meta-analyses, restricted to adults, were performed to calculate pooled odds ratios (OR) of LC in three comparisons: vaccinated (any dose) versus unvaccinated; booster vaccination versus unvaccinated; and booster vaccination versus primary course vaccination only. Results Nineteen new studies were identified, of which ten were included in the updated meta-analyses alongside eight studies from the original review. The pooled OR of LC in vaccinated adults (any dose) versus unvaccinated was 0.75 (95% confidence interval [CI] 0.67-0.84; 13 studies). ORs were also lower for booster vaccination versus unvaccinated (0.73; 95% CI 0.65-0.82; 6 studies), and booster vaccination versus primary course vaccination (0.63; 95% CI 0.53-0.75; 6 studies). Significant associations between vaccination and lower LC odds were observed in subgroup analyses of mRNA-only vaccination and LC outcomes three or more months after infection. Conclusions This updated review and meta-analysis reinforces our previous finding that vaccination may reduce the burden of LC in the Omicron era, with booster doses potentially providing additional protection. Although evidence in high-risk groups now prioritised for vaccination in most countries remains limited, these findings clearly demonstrate the benefits of vaccination and support current seasonal vaccination strategies.

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Costs of influenza-associated healthcare: an umbrella review and meta-regression analysis

Goodfellow, L.; Young, G. T. B.; van Leeuwen, E.; Lambach, P.; Jit, M.; Eggo, R. M.; Procter, S. R.

2026-10-11 health economics 10.64898/2026.10.08.26365049 medRxiv
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Abstract Background Estimates of the healthcare costs associated with influenza treatment are essential for cost-effectiveness analyses that inform preventative and treatment strategies such as vaccination and non-pharmaceutical interventions. Existing evidence varies across treatment settings, age groups, and countries and there is little data from low- and middle-income settings. Methods We conducted an umbrella review of systematic reviews and meta-analyses reporting direct admitted and non-admitted hospitalisation costs of seasonal influenza treatment in children, adults, and older people. We supplemented an evidence gap with a systematised review of studies reporting adult non-admitted treatment costs. Costs were extracted and adjusted to 2023 USD. We fitted a Bayesian mixed-effects model to estimate influenza treatment costs using national economic indicators, age group, and treatment setting as a priori predictors. We predicted admitted and non-admitted treatment costs for children, adults, and older people in 195 countries and territories. Results Seven reviews were included in the umbrella review, supplemented by 17 primary studies for adult non-admitted care. Extracted data points most frequently described admitted treatment costs and came from high-income countries. The best-fitting model used healthcare expenditure per capita to predict treatment costs, with country-level random effects. Estimated costs increased with healthcare expenditure per capita, were higher for admitted than non-admitted care, and were highest for adults and lowest for children. Conclusions This study provides novel estimates of influenza-associated healthcare costs across age groups and treatment settings by synthesising the available global evidence. By extrapolating to settings without data, our estimates can inform future economic evaluation studies of influenza interventions worldwide.

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Seroprevalence and awareness of hepatitis C infection among informal workers at Kejetia Market, Ghana: A cross-sectional study

Okwan, D. K.; Boateng, D.-G. K. O.; Takyi, P.; Obeng, M. A.; Attah, J. K.; Oduro, P.; Boateng, C. O.; Ahadzie, S. Y. N.; Scott, G. Y.; Yeboah, A.; Abrampah, A. A.; Ibrahim, K. D.; Boakye, F. K.; Nouwati, D. D.; Amankwah, K. B.; Shardow, A. L. K.; Rahamani, A. A.

2026-10-06 epidemiology 10.64898/2026.10.04.26364720 medRxiv
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Globally, Hepatitis C Virus (HCV) infection is a leading cause of chronic liver disease and remains a significant public health threat in Ghana. However, there is a paucity of data on the prevalence and awareness of HCV among market sellers and informal workers in Ghana. This study sought to determine the prevalence and awareness of HCV among this population. This was a cross-sectional study conducted among 397 sellers and workers at Kejetia market from December 2024 to January 2025. HCV was diagnosed using the One Test Hepatitis C Virus Test Strip (Qingdao Hightop) for the qualitative detection of HCV antibodies. Data were analysed using SPSS version 26 and GraphPad Prism version 8.0. A p < 0.05 was considered statistically significant for awareness of HCV. The prevalence of HCV in this study was 4 (1.0%). Awareness of HCV was low at 112 (28.2%). Residence (p=0.021) and age group (p=0.040) were significantly associated with HCV awareness. Age 41-50 years was almost three times more likely to be aware of Hepatitis C infection compared to [&le;] 30 years. Although the prevalence of HCV was low, awareness of the infection was also limited; this highlights the need for public health authorities to implement targeted HCV education programs in major markets to effectively reach informal sector workers who are often overlooked by conventional campaigns.

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Potential impact of changes in influenza vaccination coverage and effectiveness on pediatric influenza burden in the United States, 2022/23-2024/25

Morris, S. E.; Mathis, S. M.; Chung, J. R.; DeCuir, J.; Olson, S. M.; Ellington, S.; O'Halloran, A.; Ujamaa, D.; Bozio, C. H.; Jain, A.; Srivastav, A.; Lu, P.-j.; Grohskopf, L. A.; Reed, C.; Iuliano, A. D.; Biggerstaff, M.

2026-10-01 epidemiology 10.64898/2026.09.25.26363797 medRxiv
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Background and Objectives: Influenza vaccination has a strong safety record and is effective in reducing pediatric influenza-associated morbidity and mortality. However, pediatric vaccination coverage (VC) has declined since the 2019/20 influenza season in the United States. We estimated the impact of increased vaccine protection (through increased VC and/or vaccine effectiveness [VE]) on pediatric influenza-associated burden during the 2022/23-2024/25 seasons. Methods: We used a compartmental model and laboratory-confirmed influenza-associated hospitalization, VC, and VE data among children 6 months-17 years to estimate influenza burden from 2022/23-2024/25 (the 'baseline' scenario) and the impact of vaccination. We simulated scenarios that (1) increased VC by five percentage points; (2) increased VE by five percentage points; (3) increased VC and VE by five percentage points; and (4) increased VC to levels achieved in 2019/20 (the season with the highest pediatric VC to date). We estimated the difference in hospitalizations and deaths between each scenario and the baseline scenario. Results: Among children 6 months-17 years, an estimated 120,000 influenza-associated hospitalizations and 1,650 deaths occurred across all seasons at baseline. Increasing VC to 2019/20 levels had the greatest estimated impact, reducing hospitalizations by 8,670 (7.2%) and deaths by 130 (7.9%). Increasing both VC and VE by five percentage points reduced hospitalizations by 6.6% and deaths by 6.7%, whereas increasing VC or VE by five percentage points reduced hospitalizations by 3.1% and deaths by 3.2%. Conclusions: Increasing pediatric influenza vaccination coverage back to 2019/20 levels was estimated to significantly reduce pediatric influenza-associated morbidity and mortality.

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Patterns of Influenza Vaccine Uptake by Age Group and Product Type in Michigan, 2017-2021

Zhou, Z.; Malosh, R.; Sudan, S.; Wagner, A.; Eisenberg, M. C.; Monto, A.; Martin, E. T.

2026-10-21 epidemiology 10.64898/2026.10.19.26365920 medRxiv
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Background Influenza vaccines have seen many changes over recent years in terms of both policy recommendations and product types. Immune responses and vaccine effectiveness vary by vaccine strain composition and product type. This study aimed to explore this variation on a regional level through examining spatial and temporal autocorrelations of vaccine uptake of different product types within Michigan from 2017 to 2021. Methods Influenza vaccine administration data from the 2017/18 to 2021/22 seasons were obtained from the Michigan Care Improvement Registry. Population size estimates for 2017 and 2019 were obtained from the Michigan Department of Health and Human Services. Age-standardized and age-stratified vaccination rates were computed. Disparate county-level vaccine uptake clusters were constructed using spatial autocorrelation indicators and spatiotemporal clusters were identified using scan statistics. Linear mixed effect models were used to study the impact of social vulnerability and urbanicity level on seasonal influenza vaccination rate. Results Vaccination incidence rates for adjuvanted, recombinant, and nasal sprays vaccines and for any vaccines increased significantly through the study period. County-level spatiotemporal clusters of type-specific uptake rates were identified. Most notably, we identified an emerging cluster with high uptake of adjuvanted vaccine radiating from Ottawa County, located in suburban Grand Rapids, and the disappearance of high uptake cluster for high-dose vaccine uptake in the area. Vaccination rates by any product type were found to vary seasonally and showed weak negative association with more rural regions. The overall vaccination rates appear to be lower among counties with higher social vulnerability in certain urbanicity levels, but social vulnerability and urbanicity were not significantly associated with overall vaccination rate during the study period. Conclusions Vaccine type-specific uptake was spatially and temporally diverse in Michigan between 2017 and 2022. Mid and Northern Michigan had consistently relatively lower vaccination rate compared to other regions in Michigan.