Abstract Dermatophilus congolensis is a zoonotic gram-positive bacterium causing dermatophilosis, a skin infection primarily affecting animals and uncommonly reported in humans. Although human infections have traditionally been associated with animal contact, recent reports suggest alternative transmission pathways. We investigated an outbreak among contact sport athletes in Trondheim, Norway, during July to September 2025, using structured interviews and whole-genome sequencing. Nine confirmed cases were identified. Symptoms were mild and consisted mainly of pustular lesions affecting the face, arms, back, and chest. None of the cases reported animal contact. Genomic analysis confirmed species identity and showed that outbreak isolates were highly related, differing by only 0-7 core-genome single nucleotide polymorphisms. The Trondheim isolates clustered with strains from recent outbreaks in Spain and France, suggesting international dissemination of a shared clone. These findings identify contact sports as a potential setting for transmission of human dermatophilosis and highlight the value of genomic surveillance for outbreak investigation.

Introduction Swine may act as 'epidemiological bridges' and reservoirs for the emergence of novel zoonotic influenza viruses with pandemic potential. While bidirectional exchange of influenza A viruses at the swine-human interface is well recognised, data on the extent of interspecies transmission are limited.Methods We analysed the post-seasonal geometric mean titre (GMT) of influenza A(H1N1)pdm09 antibodies in humans and the seasonal prevalence of influenza A(H1N1)pdm09 antibodies in unvaccinated swine from 2009/2010-2022/2023 per county in Norway to search for evidence of interspecies transmission. We explored correlations at the national and individual county level and investigated possible associations by running a negative binomial regression model. Additionally, we distributed an influenza vaccination questionnaire to veterinarians and farmers working with swine to assess vaccination uptake and calculated total response rates per county and overall.Results The time series of H1N1pdm09 antibodies from humans and swine show significant positive correlations both across (0.8 Pearson correlation coefficient) and within certain individual counties, with especially high correlations in Innlandet (0.9), Vestland (0.8) and Rogaland (0.7) Counties. Our regression analysis revealed a significant positive association between the annual GMT of H1N1pdm09 antibodies in humans, the annual seroprevalence of H1N1pdm09 antibodies in swine, and the density of swine farms in counties. Vaccination uptake was 39% and 50% in farmers and veterinarians, respectively.Conclusions Our findings indicate a temporal relationship between the disease in humans and swine; suggesting spillover, environmental factors facilitating disease spread, and/or indirect relationships driven by unknown factors.Impacts The time series of H1N1pdm09 antibodies in humans and swine shows significant correlations. Regression analysis links GMT of H1N1pdm09 antibodies in humans to seroprevalence of H1N1pdm09 in swine and density of swine farms. This indicates a temporal relationship possibly due to spillover, shared risk factors or indirect relationships driven by unknown factors. The influenza vaccination survey showed a 39% uptake among farmers and 50% among swine veterinarians.

Our understanding of how migratory wildlife populations affect incidence of infectious diseases spilling over into humans is limited. Ticks are expanding their distribution towards northern latitudes, causing emergence of tick-borne diseases. Deer serve as reproduction hosts for adult ticks, supporting the tick populations. However, in northern areas, deer populations are partially migratory, and migrants occupy high elevation summer ranges that are unsuitable for ticks. Migration can thus theoretically lead to escape from exposure to ticks and to deer feeding fewer ticks, which lower disease hazard to humans. Combining data on Ixodes ricinus tick abundance with GPS-tracking data of red deer (Cervus elaphus), we quantified the distributional overlap of ticks and red deer along elevational gradients in Norway. Furthermore, we correlated both deer density and the proportion of migratory deer with the incidence of Lyme disease in humans. We found that migratory deer summer ranges had colder climate and overlapped less with tick distribution than those of resident deer. Deer density consistently increased Lyme disease incidence in humans. However, we found only weak evidence that deer migration negatively affected Lyme disease incidence. Our study provides a rare quantification of how host availability, in terms of both host density and migratory movement, affects risk of a zoonotic disease.

AIM:Adverse human-driven environmental change, including the climate, is having an increasing impact on the Arctic environment and its ecosystems. There has been immense interest in understanding the health risks related to climate change in the Arctic region. In this article, we review recent evidence related to climate change and its impacts on the health of the Arctic population. METHODS:We summarize current evidence related to primary, secondary and tertiary health effects in the Arctic. We explore a broad range of effects on health including increased exposure to extreme weather, impacts from changes in water quality, air quality, contaminant exposure, food systems and patterns of infectious diseases. We also briefly discuss mental health effects in the Arctic. We conclude by examining further challenges and opportunities for research in this field and advocate the need for adaptation options in the Arctic. RESULTS:We find that there is a large amount of literature that is focusing on the human health effects in the Arctic but there are still research gaps in terms of understanding these compared with those at lower latitudes. We point out the need for filling several of these knowledge gaps to project future health effects of climate change in the Arctic. CONCLUSIONS:There is a need for integrated adaptation strategies in the Arctic that fully account for the health impacts and consider indigenous perspectives.

Tick-borne encephalitis (TBE) is one of the more severe and widespread arboviral infections in Europe, with an increase in incidence over the past decades in several countries. Prevention strategies against infection with the virus include vaccination and protection against tick bites. The virus is typically found in very localized endemic areas known as microfoci, possibly affecting differences in public knowledge and vaccination strategies between countries and regions. This study investigated how self-reported TBE vaccination status is associated with demographic variables, knowledge of TBE, and tick and TBE virus exposure in Denmark, Norway, and Sweden. An online questionnaire with 48 questions, including demographic prompts, knowledge questions about TBE, and TBE vaccination status was sent out to respondents in the three countries. The overall proportion of reportedly TBE-vaccinated people in the three countries (N = 2668) was 13 %, but with large differences between countries. The proportion was 28.5 % in Sweden (N = 1096), 2.3 % in Norway (N = 789) and 2.2 % in Denmark (N = 783), corresponding well with the higher TBE incidence in Sweden. The reported TBE-vaccination rates in Denmark and Norway were too low for further analyses. The results from Sweden were analysed by logistic regression, showing that respondents in Sweden who reportedly visited TBE virus risk areas were more likely to be vaccinated. The general knowledge of TBE appeared to be limited, especially in Denmark and Norway.

BACKGROUND Toxoplasma gondii is a zoonotic protozoan capable of infecting warm-blooded animal species and humans. Although toxoplasmosis presents mostly as mild or asymptomatic infection in immunocompetent individuals, in unborn children and people with weakened immune systems, the disease can be severe with ocular, neurological or multi-systemic manifestations and even death. AIM We aimed to collate and analyse data on T. gondii seroprevalence in humans to model and compare age-dependent prevalence in geographic regions in Europe. METHODS A systematic review identified 1,822 scientific publications, from which seroprevalence data were extracted from 69 studies. Data were analysed using a Bayesian hierarchical model. RESULTS The modelling of the seroprevalence indicated the highest incidence rates in eastern (50%) and western (48%) Europe, with the lowest estimates in northern Europe (18%) and the United Kingdom (UK) (18%). Eastern and western Europe were regions where T. gondii infections occurred earliest in life, with half of the population expected to be seropositive by the age of 44 and 47 years, respectively. In contrast, in northern Europe and the UK the modelled median time to infection exceeded 170 years. CONCLUSION Results of the study provide a robust baseline for future epidemiological research on human T. gondii infections in Europe and may be useful to validate subsequent research, such as risk assessment studies.

Whole-genome sequencing (WGS) is increasingly used as the primary typing method for foodborne disease surveillance. It offers high-resolution cluster analysis, interoperability, and comprehensive pathogen characterization. However, implementing WGS-based foodborne surveillance also poses challenges. This paper outlines these challenges and provides practical recommendations. It requires a business plan that details the financial, technical and human resources needed, since setting up WGS-based surveillance requires substantial initial investments. During the initial phase, the per sample costs of WGS are likely higher than with traditional typing method. However, this will align or even go below that when fully transitioned to WGS-based surveillance because WGS data can be used for multiple purposes such as (sero)typing and antimicrobial and virulence characterization. It is advisable to start with a single pathogen to establish a solid foundation, with the aim of having one institutional sequencing facility. Validating accuracy and consistency of results is crucial before expanding to other pathogens. While cross-disciplinary collaboration has always played an important role in foodborne surveillance, the complexity of WGS results now makes it essential for transforming findings into effective interventions. Despite its challenges, advancements in technology and computation capabilities have made it increasingly accessible, ultimately improving public health surveillance and response.

The risk of zoonotic disease transmission from animals to humans is elevated for people in close contact with domestic and wild animals. About three-quarters of all known human infectious diseases are zoonotic, and potential health impacts of these diseases are higher where infectious disease surveillance and access to health care and public health services are limited. This is especially the case for remote circumarctic regions, where drivers for endemic, emerging, and re-emerging zoonotic diseases include anthropogenic influences, such as pollution by long-range transport of industrial chemicals, climate change, loss of biodiversity and ecosystem alterations. In addition to these, indirect effects including natural changes in food web dynamics, appearance of invasive species, thawing permafrost also affect the risk of zoonotic disease spill-over. In other words, the Arctic represents a changing world where pollution, loss of biodiversity and habitat, and maritime activity are likely driving forward occurrence of infectious diseases. As a broad international consortium with a wide range of expertise, we here describe a selection of case studies highlighting the importance of a One Health approach to zoonoses in the circumarctic, encompassing human health, animal health, and environmental health aspects. The cases highlight critical gaps in monitoring and current knowledge, focusing on environmental stressors and lifestyle factors, and they are examples of current occurrences in the Arctic that inform on critically needed actions to prepare us for the future. Through these presentations, we recommend measures to enhance awareness and management of existing and emerging zoonoses with epidemic and pandemic potential while also focusing on the impacts of various environmental stressors and lifestyle factors on zoonoses in the Arctic.

There is growing awareness and recognition of the importance of the One Health paradigm to address existing environmental threats and recognise emerging ones at an early stage among Arctic residents, public health agencies, and wildlife resource managers. The One Health approach, emphasising the interconnectedness of human, animal, and ecosystem health, plays a pivotal role in addressing these multifaceted issues. Warming climate and permafrost thaw may influence both contaminant exposure and the spread of zoonotic infectious diseases and have impacts on water and food security. Migration from rural regions to larger communities and urban centres along with increased tourism may be accompanied by changes in exposure to contaminants and zoonotic diseases. Universities have developed educational programmes and research projects on One Health in the Arctic, and under the Arctic Council there is running a project of One Arctic, One Health. These arctivities have produced interdisciplinary information and practical solutions for local communities, decision-makers, and in scientific forums. There is a need for epidemiological zoonotic/human disease models, as well as new approaches to integrate existing and future surveillance data to climatic and environmental data. This requires not only regional and international collaboration but also multi-agency and transdisciplinary research.

Surveillance data derived from the Norwegian Surveillance System for Communicable Diseases database that summarises the weekly number of Lyme borreliosis cases on a regional and national scale from 1995-2019. Census population data is also included in the file.

Tick-borne encephalitis (TBE) is a viral disease endemic in Eurasia. The virus is mainly transmitted to humans via ticks and occasionally via the consumption of unpasteurized milk products. The European Centre for Disease Prevention and Control reported an increase in TBE incidence over the past years in Europe as well as the emergence of the disease in new areas. To better understand this phenomenon, we investigated the drivers of TBE emergence and increase in incidence in humans through an expert knowledge elicitation. We listed 59 possible drivers grouped in eight domains and elicited forty European experts to: (i) allocate a score per driver, (ii) weight this score within each domain, and (iii) weight the different domains and attribute an uncertainty level per domain. An overall weighted score per driver was calculated, and drivers with comparable scores were grouped into three terminal nodes using a regression tree analysis. The drivers with the highest scores were: (i) changes in human behavior/activities; (ii) changes in eating habits or consumer demand; (iii) changes in the landscape; (iv) influence of humidity on the survival and transmission of the pathogen; (v) difficulty to control reservoir(s) and/or vector(s); (vi) influence of temperature on virus survival and transmission; (vii) number of wildlife compartments/groups acting as reservoirs or amplifying hosts; (viii) increase of autochthonous wild mammals; and (ix) number of tick species vectors and their distribution. Our results support researchers in prioritizing studies targeting the most relevant drivers of emergence and increasing TBE incidence.

Lyme borreliosis, the most common vector-borne disease in Europe and North America, is attracting growing concern due to its expanding geographic range. The growth in incidence and geographic spread is largely attributed to climate and land-use changes that support the tick vector and thereby increase disease risk. Despite a wide range of symptoms displayed by Lyme borreliosis patients, the demographic patterns in clinical manifestations and seasonal case timing have not been thoroughly investigated and may result from differences in exposure, immunity and pathogenesis. We analysed 25 years of surveillance data from Norway, supplemented by population demography data, using a Bayesian modelling framework. The analyses aimed to detect differences in case seasonality and clinical manifestations of Lyme borreliosis across age and sex differentiated patient groups. The results showed a bimodal pattern of incidence over age, where children (0-9 years) had the highest incidence, young adults (20-29 years) had low incidence and older adults had a second incidence peak in the ages 70-79 years. Youth (0-19 years) presented with a higher proportion of neuroborreliosis cases and a lower proportion of arthritic manifestations compared to adults (20+ years). Adult males had a higher overall incidence than adult females and a higher proportion of arthritis cases. The seasonal timing of Lyme borreliosis consistently occurred around 4.4 weeks earlier in youth compared to adults, regardless of clinical manifestation. All demographic groups exhibited a shift towards an earlier seasonal timing over the 25-year study period, which appeared unrelated to changes in population demographics. However, the disproportionate incidence of Lyme borreliosis in seniors requires increased public awareness and knowledge about this high-risk group as the population continues to age concurrently with disease emergence. Our findings highlight the importance of considering patient demographics when analysing the emergence and seasonal patterns of vector-borne diseases using long-term surveillance data.

Climate change has had a major impact on seasonal weather patterns, resulting in marked phenological changes in a wide range of taxa. However, empirical studies of how changes in seasonality impact the emergence and seasonal dynamics of vector-borne diseases have been limited. Lyme borreliosis, a bacterial infection spread by hard-bodied ticks, is the most common vector-borne disease in the northern hemisphere and has been rapidly increasing in both incidence and geographical distribution in many regions of Europe and North America. By analysis of long-term surveillance data (1995-2019) from across Norway (latitude 57°58'-71°08' N), we demonstrate a marked change in the within-year timing of Lyme borreliosis cases accompanying an increase in the annual number of cases. The seasonal peak in cases is now six weeks earlier than 25 years ago, exceeding seasonal shifts in plant phenology and previous model predictions. The seasonal shift occurred predominantly in the first 10 years of the study period. The concurrent upsurgence in case number and shift in case timing indicate a major change in the Lyme borreliosis disease system over recent decades. This study highlights the potential for climate change to shape the seasonal dynamics of vector-borne disease systems.

During the pandemic outdoor activities were encouraged to mitigate transmission risk while providing safe spaces for social interactions. Human behaviour, which may favour or disfavour, contact rates between questing ticks and humans, is a key factor impacting tick-borne encephalitis (TBE) incidence. We analyzed annual and weekly TBE cases in Finland, Norway and Sweden from 2010 to 2021 to assess trend, seasonality, and discuss changes in human tick exposure imposed by COVID-19. We compared the pre-pandemic incidence (2010-2019) with the pandemic incidence (2020-2021) by fitting a generalized linear model (GLM) to incidence data. Pre-pandemic incidence was 1.0, 0.29 and 2.8 for Finland, Norway and Sweden, respectively, compared to incidence of 2.2, 1.0 and 3.9 during the pandemic years. However, there was an increasing trend for all countries across the whole study period. Therefore, we predicted the number of cases in 2020/2021 based on a model fitted to the annual cases in 2010-2019. The incidences during the pandemic were 1.3 times higher for Finland, 1.7 times higher for Norway and no difference for Sweden. When social restrictions were enforced to curb the spread of SARS-CoV-2 there were profound changes in outdoor recreational behavior. Future consideration of public health interventions that promote outdoor activities may increase exposure to vector-borne diseases.

Summary The aim of this work, performed in the framework of the One Health (OH) European Joint Program, was to identify barriers (issues) and opportunities (suggestions) for an integrated OH surveillance of food-borne diseases in Belgium, France, Sweden, Norway. Information has been collected through 20 interviews with professionals with selected profiles from the four countries (human epidemiologists, persons from administration in charge of planning the annual food chain surveillance, veterinary epidemiologists, transversal coordinators of national agencies positioned on the link between risk analysis and management, coordinators of the human and veterinary National Reference laboratories). The information collected through the interviews has been analysed following the thematic analysis methodology. According to the analysis performed, the barriers and opportunities identified by the interviewees were grouped in eight themes: (1) Data governance, (2) Set-up and operations of the surveillance system, (3) Coordination, (4) Communication, (5) Regulations (political legislations and procedures), (6) Industry’s challenges, (7) Funding, (8) Training and education. The most important barriers for all countries were indicated for the themes (1) and (2). A detailed analysis of the collected information has also been performed per identified theme, with various practical issues and opportunities being identified, taking into account the particularities of each country. The results show that there is room for improvement in food-borne disease surveillance of microbiological pathogens towards a OH approach, especially regarding the themes identified as most important. The results can be used when revising existing systems, or when developing new systems for food-borne disease surveillance from a OH perspective.

Foodborne outbreaks represent a significant public health burden. Outbreak investigations are often challenging and time-consuming, and most outbreak vehicles remain unidentified. The development of alternative investigative strategies is therefore needed. Automated analysis of Consumer Purchase Data (CPD) gathered by retailers represents one such alternative strategy. CPD-aided investigations do not require trawling questionnaires to create a hypothesis and can provide analytical measures of association by direct data analysis. Here, we used anonymized CPD from 920,384 customers enrolled in Norway's largest supermarket loyalty program to simulate foodborne outbreaks across a range of different parameters and scenarios. We then applied a logistic regression model to calculate an odds ratio for each of the different possible food vehicles. By this method, we were able to identify outbreak vehicles with a 90% accuracy within a median of 6 recorded case-patients. The outbreak vehicle identification rate declined significantly when using data from only one of two retailers involved in a simulated outbreak. Performance was also reduced in simulations that restricted analysis from product ID to the product group levels accessible by trawling questionnaires. Our results show that-assuming agreements are in place with major retailers-CPD collection and analysis can solve foodborne outbreaks originating from supermarkets both more rapidly and accurately than than questionnaire-based methods and might provide a significant enhancement to current outbreak investigation methods.

Identifying a specific product causing a foodborne disease outbreak can be difficult, especially when dealing with a large amounts of suspicious food items and weak epidemiological evidence. A previously described likelihood model (Norström et al. 2015), improved within the OHEJP NOVA project, helps to prioritize food products that should be sampled for laboratory analysis. It is the aim of our study to integrate this approach into state of the art tracing software FoodChain-Lab (FCL; https://foodrisklabs.bfr.bund.de/foodchain-lab) developed at BfR to facilitate outbreak investigations. The model improved by Kausrud et al. in R (Ihaka and Gentleman 1996) uses wholesale data, the distribution of disease cases and census data to sort food items by their estimated likelihood to be the source of an outbreak. We developed a fast and secure intuitive software module using the Web Assembly technology (Haas et al. 2017) allowing professionals to embed the module easily into other applications. We integrated the module into the FCL web application for tracing (FCL Web; https://fcl-portal.bfr.berlin) to provide an intuitive and user-friendly solution. This solution combines a simple data input with extended data wrangling to make the calculation of the NOVA model as easy as possible. Since the model can be executed directly inside the web browser and therefore does not rely on any server environment, the possibility of data leakage can be highly reduced. The implementation of the advanced likelihood model into FCL Web increase the availability of this model and provides investigators easy, fast and reliable usage to improve outbreak investigation workflows.

Abstract Background Closed fitness centers during the Covid-19 pandemic may negatively impact health and wellbeing. We assessed whether training at fitness centers increases the risk of SARS-CoV-2 virus infection. Methods In a two-group parallel randomized controlled trial, fitness center members aged 18 to 64 without Covid-19-relevant comorbidities, were randomized to access to training at a fitness center or no-access. Fitness centers applied physical distancing (1 m for floor exercise, 2 m for high-intensity classes) and enhanced hand and surface hygiene. Primary outcomes were SARS-CoV-2 RNA status by polymerase chain reaction (PCR) after 14 days, hospital admission after 21 days. The secondary endpoint was SARS-CoV-2 antibody status after 1 month. Results 3764 individuals were randomized; 1896 to the training arm and 1868 to the no-training arm. In the training arm, 81.8% trained at least once, and 38.5% trained ≥six times. Of 3016 individuals who returned the SARS-CoV-2 RNA tests (80.5%), there was one positive test in the training arm, and none in the no-training arm (risk difference 0.053%; 95% CI − 0.050 to 0.156%; p = 0.32). Eleven individuals in the training arm (0.8% of tested) and 27 in the no-training arm (2.4% of tested) tested positive for SARS-CoV-2 antibodies (risk difference − 0.87%; 95%CI − 1.52% to − 0.23%; p = 0.001). No outpatient visits or hospital admissions due to Covid-19 occurred in either arm. Conclusion Provided good hygiene and physical distancing measures and low population prevalence of SARS-CoV-2 infection, there was no increased infection risk of SARS-CoV-2 in fitness centers in Oslo, Norway for individuals without Covid-19-relevant comorbidities. Trial registration The trial was prospectively registered in ClinicalTrials.gov on May 13, 2020. Due to administrative issues it was first posted on the register website on May 29, 2020: NCT04406909 .

Consumer purchase data (CPD) can be a powerful tool in the investigation of foodborne outbreaks through analyses of electronic records of food that individuals buy. The objective of this study was to develop a common framework for use of CPD in foodborne outbreak investigations using the expertise of European public health professionals from 11 European countries. We also aimed to describe barriers and limitations preventing CPD utilization. CPD are mainly gathered from supermarket loyalty programmes, smaller consortia, and independent supermarkets. Privacy legislation governing CPD was perceived as the most crucial barrier for CPD usage, but still resolvable. The main practical challenges were obtaining consumer consent for CPD usage, the associated workload, data access, format, and analysis. Harmonising methods and reporting across countries, standardised consent forms and electronic consent methods were identified as solutions. This guideline was developed to support outbreak investigators in overcoming barriers in using CPD, thereby increasing public health professionals' application and value of this powerful investigation tool. In addition, we hope this framework will lead to more public health institutions, in collaboration with food safety authorities, making use of CPD in outbreak investigations in the future.