Search Results (442)

West Nile virus (WNV) remains the most frequently reported locally acquired arboviral infection in the United States, yet many small and mid-sized mosquito abatement districts lack the diagnostic capacity and integrated data systems needed for rapid detection and response. The Canyon County Mosquito Abatement District (CCMAD) in southwestern Idaho undertook a multi-year capacity-building effort to expand arbovirus surveillance, standardize mosquito identification and pooling procedures, and implement triplex RT-qPCR testing for WNV, Western equine encephalitis virus (WEEV), and St. Louis encephalitis virus (SLEV). Historical trapping datasets (2021–2025) were consolidated, geospatially harmonized, and grouped into biologically meaningful sampling units to enable multi-year spatial comparisons. Surveillance revealed recurrent WNV activity annually, with peak transmission occurring between epidemiological weeks 31 and 37. The highest WNV activity occurred in 2023 and 2025, with 192 and 92 positive pools, respectively, while no WEEV or SLEV detections were observed. Enhanced laboratory capacity reduced sample-processing times, decreased the reliance on external confirmatory testing, lowered per-pool testing costs, and enabled same-day reporting to operational staff. In 2025, routine gravid trap surveillance detected a single Aedes aegypti, which was identified morphologically and subsequently confirmed by DNA barcoding, prompting targeted follow-up trapping. CCMAD’s integrated approach provides a scalable model for strengthening local surveillance and response capabilities in resource-limited settings. Full article

West Nile virus (WNV) is a mosquito-borne flavivirus of growing importance for both human and equine health in Europe. Horses are highly susceptible to neurological disease and, because they share ecological exposure with humans, they represent valuable sentinels for detecting local viral circulation within a One Health framework. However, diagnosis of WNV infection in equines is complicated by the short and low-level viraemia, which limits the sensitivity of molecular assays, and by serological cross-reactivity with related flaviviruses and the confounding effects of vaccination. In this narrative review, we summarise the current diagnostic tools for WNV in horses, including direct detection methods (RT-qPCR, virus isolation, antigen detection) and indirect serological approaches (IgM and IgG ELISA, virus neutralisation tests), and discuss their practical performance and constraints in clinical and surveillance settings. We further examine equine surveillance systems, passive clinical reporting, active serosurveys and sentinel cohorts, and their integration with vector, avian and environmental monitoring. Key challenges include methodological heterogeneity, limited access to confirmatory testing and variable cross-sector data sharing. Finally, we outline future directions, highlighting the need for harmonised laboratory protocols, innovative field-deployable diagnostics, genomic surveillance and integrated, multi-source monitoring systems to strengthen early warning capacity and improve preparedness for WNV outbreaks in equine populations. Full article

Zoonotic diseases account for approximately one billion cases of illness and millions of deaths globally each year. Increasing contact between humans and competent wildlife hosts elevates the risk of zoonotic spillover. Synanthropic bird species are key players in the transmission of zoonotic pathogens, including flaviviruses such as West Nile virus (WNV) and influenza A viruses like Avian Influenza Virus (AIV). Active surveillance of sentinel birds inhabiting urban areas allows for early detection of emerging pathogens before they cause zoonotic outbreaks. Despite nesting in close proximity to humans, the role of the house martin (Delichon urbicum) in the circulation of flaviviruses and AIV remains poorly understood. Here, we analyzed the presence of antibodies against flaviviruses and AIV in a colony of house martins from southwestern Spain. In addition, we aimed to detect amplicons of the matrix and nucleoprotein genes of AIV using RT-qPCR. While none of the samples tested positive for AIV by RT-qPCR, we observed an AIV seroprevalence of 2.13% based on non-subtyped ELISA. Notably, this is the first report of AIV-seropositive D. urbicum individuals captured in Spain. Moreover, we detected a flavivirus-group seroprevalence of 24.34%, similar to rates reported in the same house martin population between 2018 and 2020, suggesting widespread circulation of flaviviruses within this synanthropic species. These results support the hypothesis that house martins may participate in the transmission of these viruses between wild bird populations and humans in urban environments. Full article

West Nile virus (WNV) is a mosquito-borne flavivirus that remains an important public and veterinary health concern across Europe. Periodic outbreaks affecting humans, horses, and wildlife highlight the complex ecological interactions underlying viral circulation. This narrative review aims to synthesize current knowledge regarding WNV epidemiology, transmission dynamics, and surveillance strategies in Europe, with particular attention to the Romanian context. Available surveillance data indicate recurrent seasonal transmission in several European regions; however, reported case numbers may be influenced by differences in diagnostic capacity, reporting practices, and surveillance intensity among countries. Recent studies suggest that environmental variability, vector adaptation, and host community composition play important roles in shaping regional transmission risk, although the relative contribution of these factors remains incompletely quantified. Despite expanding surveillance networks and One Health initiatives, important knowledge gaps persist regarding the integration of environmental risk indicators, vector ecology, and operational preparedness into coherent risk-assessment frameworks. This review therefore examines current epidemiological patterns, evaluates surveillance approaches, and discusses emerging drivers of WNV transmission in Europe. As a narrative synthesis based on published literature and surveillance reports, this review is subject to limitations related to heterogeneity in available data and differences in national reporting systems. Nevertheless, a clearer understanding of these interacting factors may support improved surveillance strategies and more adaptive public health responses to future WNV transmission events. Reported surveillance data should be interpreted cautiously, as differences in national surveillance intensity, diagnostic capacity, and reporting frameworks across Europe may influence notified case numbers. Consequently, reported outbreaks do not necessarily reflect proportional differences in transmission intensity. Full article

The circulation of viruses of medical and veterinary importance is monitored to evaluate risks to both human and animal health. Among the species most commonly used in surveillance programs, the wild boar (Sus scrofa) plays a key role due to its high population density and its contacts with rural swine herds in the areas under investigation. In the present study, molecular (real-time PCR) and serological analyses were conducted on wild boar samples collected in the regions of Apulia, Basilicata, Campania, and Calabria. Specifically, molecular detection was applied to IAVs, FLVs, and Porcine PCV-2, while serological testing was used to assess exposure to IAVs, FLVs, and ADV. Serological results showed an 8.31% positivity for IAVs, whereas viral presence detected by PCR was 1.17%. No active infections were detected for WNV, with only a single seropositive sample (0.30%), while ADV showed a seroprevalence of 2.61%. PCV-2 was detected exclusively by molecular analysis in 66 out of 223 tested animals (29.6%). The overall objective of the study is to deepen the understanding of virus circulation in the wildlife of Southern Italy, using the wild boar as an additional sentinel species for epidemiological surveillance activities. The distinctive feature of the project lies in its multi-pathogen approach applied to a reference population distributed across a particularly wide geographical area, allowing for the simultaneous assessment of the circulation of different viruses over a large territory. Full article

West Nile neuroinvasive disease (WNND) causes substantial morbidity in endemic regions, yet data on its burden in Serbia remain limited. We conducted a retrospective, population-based study of WNND cases reported in Vojvodina Province, Serbia, from 2012 to 2025. Incidence and mortality trends were analysed by year, residence, age, sex, and week of symptom onset. Multivariable logistic regression was used to identify predictors of fatal outcome. Of 1337 suspected cases, 557 (41.66%) met the WNND case definition (530 confirmed, 27 probable cases) and 98.9% were autochthonous. The mean annual incidence was 2.17/100,000 (95% CI 0.60–3.75), ranging from 0.48/100,000 (2015) to 10.31/100,000 (2018), with additional peaks in 2013 and 2022. Cases clustered predominantly in epidemiological weeks 31–34. The mean mortality was 0.28/100,000 (95% CI 0.02–0.53) and the mean case fatality rate was 12.93% (95% CI 10.14–15.71%). Incidence increased with age, peaking at 5.97/100,000 in those 70–79 years; highest mortality occurred in ≥80 years (1.78/100,000). All districts reported cases, with the highest incidence and mortality in South Banat. Higher Charlson Comorbidity Index, cardiovascular disease, diabetes and malignancy independently predicted fatal outcome. WNND remains a significant public health problem in Vojvodina, requiring improved surveillance, targeted prevention, and early treatment of high-risk patients. Full article

West Nile virus (WNV) circulates endemically in Romania, yet prevention of WNV infection in horses largely depends on owner-driven decisions that require accurate risk perception and veterinary guidance. A cross-sectional online survey was carried out between May and November 2025 to evaluate the knowledge, attitudes, and preventive practices (KAP) regarding WNV among 227 horse owners from various Romanian regions. In total, 67.4% of respondents had previously heard of WNV. The main transmission route was correctly identified as mosquito bites by 49.8% of participants, while 32.2% answered “don’t know” or presented misconceptions: horse-to-horse contact (9.3%), tick bites (10.6%) and blood transfusion (0.4%). Recognition of clinical signs was limited, with fever (31.3% of respondents) and gait abnormalities or ataxia (24.7% of respondents) being most frequently mentioned, followed by inappetence (19.4% of respondents), seizures (18.1% of respondents), coughing (8.8% of respondents), and abortions (10.6% of respondents); 47.6% of respondents were unable to identify any specific signs. Awareness of the existence of an equine WNV vaccine was reported by 23.8% of respondents, while only 4.0% indicated that their horses had been vaccinated. The most common preventive measures included the use of insecticides in stables (61.2%) and topical repellents on horses (55.5%), whereas environmental control actions such as removing standing water (14.1%) or avoiding swampy areas (11.9%) were less frequent; 19.4% reported taking no preventive measures. Veterinary communication was limited, with only 17.2% of respondents having received information about WNV from a veterinarian, and 21.6% perceiving a real risk of infection in Romania. Overall, the data show a marked disconnect between awareness and actionable prevention (particularly vaccination and environmental mosquito control), indicating that targeted owner education must be paired with structured veterinary communication to translate knowledge into preventive uptake in endemic settings. Full article

Objective: The aim of this retrospective study was to evaluate clinical and laboratory characteristics in adult patients with neuroinvasive West Nile virus (WNDD). We also studied the phylogeny and molecular characteristics of some of the WNV strains. Methods: A retrospective analysis was conducted at “Annunziata” Hub Hospital, a secondary referral facility in Calabria region, in Southern Italy. Sample pre-processing, sequencing and bioinformatic analyses were carried out at IRCCS Sacro Cuore Don Calabria Hospital in Negrar di Valpolicella, Verona, Veneto region in North-East Italy. Results: Nine cases of WNDD were analyzed, involving eight males and one female, with a mean age of 70.33 years (range 60–85). The overall average hospital stay was 20.6 days (range 6–46). Six patients made a full recovery after a mean of 35.3 days of acute care. Thirty-day mortality rate was 23%. VNDD in some of our patients manifested itself in the form of cerebral hemorrhage (ICH) in three patients, causing lethality in two patients and other unusual manifestations, such as Guillain–Barré syndrome with fatal outcome and severe facial palsy. Phylogenetic analysis shows that our sequences are closely related to other southern-Italian and cluster with Central–Southern–Eastern European sequences, while being evidently separated from northern Italian and Central–Western European ones, belonging to the sub-lineage 2a of the WNV-2, clustering with sequences from the Central–South–Eastern clade, mainly to Hungary. Conclusions: Cerebrovascular complications of WNE may be an important clinical manifestation of WNV neuroinvasive infection. Preliminary data do not allow us to determine whether our strains, closely related to other southern-Italian and cluster with Central–Southern–Eastern European sequences, really presented an increased neurovirulence. Full article

West Nile virus (WNV) is a mosquito-borne flavivirus with one of the widest global distributions. Since its discovery in Uganda in 1937, it has become a major zoonotic pathogen, and after its introduction into the United States in 1999, it spread rapidly across the Americas, becoming the leading cause of neuroinvasive arboviral disease. Its expansion illustrates a remarkable ecological adaptability, further intensified by climate change. In Latin America and the Caribbean, WNV circulation has been consistently documented in birds, horses, and mosquitoes; however, confirmed human cases remain disproportionately scarce compared with North America and Europe. Reports include sporadic human cases in Brazil (>100 since 2014), Mexico (~13), Argentina (2006–2007), Puerto Rico (2007), Nicaragua, and Haiti, while animal and vector evidence extends to Guatemala, El Salvador, Belize, Costa Rica, Bolivia, Paraguay, Colombia, Venezuela, Cuba, and Ecuador. This paradox likely reflects structural limitations within regional health systems, including underdiagnosis, restricted diagnostic capacity, and significant surveillance gaps, particularly in contexts where mild febrile syndromes may be misclassified as dengue, Zika, or Chikungunya. The regional risk of emergence is further amplified by climatic variability, ecological change, and intensifying human–wildlife interactions. Experiences from Europe highlight the importance of early detection, transfusion safety, and integrated surveillance within a One Health framework. Strengthening preparedness in Latin America will require investments in diagnostic infrastructure, implementation of standardized seroepidemiological surveys, development of predictive models tailored to local ecological contexts, and robust intersectoral collaboration. Full article

West Nile virus lineage 2 (WNV-2) is a growing public health concern in Europe causing West Nile fever or West Nile neuroinvasive disease (WNND) with substantial morbidity and mortality; however, genomic data from southern Italy are limited despite recent expansion of autochthonous transmission. The aim of the study was to characterize the phylogenetic and molecular features of the WNV-2 strain responsible for the first autochthonous human infection reported in Calabria (2023), and two more additional WNND cases detected in 2024. Full WNV-2 genomes were generated from the three cases. Phylogenetic analysis was performed using all publicly available WNV sequences up to September 2025. Amino acid changes in the polyprotein were compared with known WNV-2 lineage and sub-lineage signatures. The three sequences formed a monophyletic group within sub-lineage WNV-2a, clustering with strains circulating in Central-South-Eastern Europe and showing closest affinity to Hungarian sequences. Non-synonymous substitutions characteristic of the Hungary 578/10 strain (NS2B-119I, NS4B-14G, NS4B-49A, and NS5-298A) were identified and were absent from Central-Northern-Western European and previously reported Italian sequences. Additional substitutions (E-159T, E-399R, and NS3-249P) corresponded to signatures from a fatal WNV-2 infection in a Great Grey Owl in Slovakia. Our study provides the first report of Central-South-Eastern European WNV-2 circulation outside Eastern Europe, supporting its likely spread through the Balkans into Italy by 2022. These findings underscore the rapid spread of WNV-2 in newly affected areas and highlight the critical need for sustained molecular surveillance. Full article

Background: Climate change represents a major global health challenge, with rising temperatures and altered precipitation patterns influencing the spread of infectious diseases. This study investigated the association between climatic factors (average temperature and precipitation) and the monthly proportion of laboratory-confirmed Legionella pneumophila serogroup 1 and West Nile Virus infections among clinically suspected patients in a large teaching hospital in Northern Italy. Methods: We retrospectively analyzed data from 2021 to 2024. The primary outcome was the monthly proportion of positive tests (standardized per 1000 clinically suspected patients) for Legionella pneumophila serogroup 1 (urinary antigen) and West Nile Virus (serology). Associations with climatic variables were assessed using linear and multivariate regression models, as well as Generalized Additive Models (GAMs). Seasonal effects were evaluated through ANOVA. Results: For Legionella pneumophila, precipitation was not significantly associated with the proportion of positive tests (p = 0.1438; R² = 0.049). In contrast, average temperature was a significant predictor: each 1 °C increase was associated with +0.52 positive cases per 1000 tested patients (p = 0.000283; R² = 0.267). Multivariate models confirmed temperature as the dominant factor. For West Nile Virus, precipitation showed no meaningful effect (p = 0.914). However, average temperature demonstrated a significant positive association with the proportion of positive cases (p = 0.00293; coefficient = 9.33), with seasonal analysis highlighting a marked summer peak (mean = 399.68 positive cases per 1000 tested; p = 0.00653). Conclusions: Our findings underline the predominant role of temperature over precipitation in driving the burden of both Legionella pneumophila and West Nile Virus infections among hospitalized patients. These results strengthen the evidence that the life cycles of these pathogens are tightly climate-dependent. Developing effective adaptation strategies is essential to mitigate climate-related health risks. Full article

West Nile Virus (WNV) is becoming a significant and enduring public health menace in Europe, propelled by climate changes and accelerated population aging. Most infections are asymptomatic but older adults are more prone to develop neuroinvasive disease, which is characterized by high morbidity and mortality, as well as long-term neurological disturbances and disability. To date, there is still no licensed human vaccine or specific antiviral treatment, and management is mostly supportive. This review brings together the most recent information about WNV epidemiology, pathogenesis, and clinical manifestations, with a special focus on older people in Europe. We critically analyze current and novel pharmaceutical strategies, encompassing drug repurposing, nucleoside analogues, interferon-based therapies, peptides, monoclonal antibodies, and host-directed agents, emphasizing their therapeutic potential alongside the challenges presented by age-related pharmacokinetic and immunological alterations. We also discuss some important gaps in the current evidence base, such as the frequent exclusion of older adults from clinical studies and the lack of a coordinated clinical trial infrastructure that can be quickly activated during seasonal outbreaks. Lastly, we suggest a framework that combines systematic antiviral screening with the creation of a Europe-wide network of clinical trial readiness that is built into current One Health surveillance systems. Full article

Mosquito-borne flaviviruses, including Dengue virus (DENV), Japanese encephalitis virus (JEV), West Nile virus (WNV), Yellow fever virus (YFV), and Zika virus (ZIKV), continue to present a significant threat to public health worldwide. In 2024, these viruses accounted for 11,717 reported cases in the United States and more than 7.6 million cases globally. As of early 2025, according to CDC data, 1830 cases of dengue had already been reported, with 1584 transmitted locally within the U.S. Despite the considerable burden that these diseases pose, no specific antiviral treatments exist. A very limited number of virus-specific vaccines have been licensed, such as those for YFV, JEV, and, with specific constraints, for DENV. To date, no pan-flavivirus vaccine is available. This review examines the potential of emerging vaccine platforms—particularly messenger RNA and virus-like particles—as promising tools in the pursuit of a broadly protective flavivirus vaccine. We analyze current strategies for inducing cross-neutralizing immune responses and discuss how these technologies could support the presentation of conserved quaternary epitope conformations, which are increasingly recognized as critical targets for establishing potent immune responses. We review key advances in virology, immune response, and immunogen delivery systems to highlight the potential for developing a pan-flavivirus vaccine. Full article

Background: Efficient nucleic acid extraction is essential for reliable viral load testing, yet performance can differ widely depending on the extraction system and sample type. We compared three automated platforms, QIAcube, EZ1 Advanced, and Maxwell RSC, for their ability to recover cytomegalovirus (CMV) DNA and West Nile virus (WNV) RNA from common clinical matrices. Methods: Mock specimens were prepared using whole blood, plasma, serum, and urine collected from two donors. Samples were spiked with CMV or WNV culture material and extracted in triplicate on each platform according to the manufacturers’ protocols. Viral loads were measured using ELITech ELITE MGB assays on the InGenius system. Whole blood samples were also tested after a 1:4 dilution. Matrix-specific standard curves were applied, and viral loads were compared using Wilcoxon rank-sum tests with false-discovery rate adjustment. Results: Extraction efficiency differed substantially by platform and specimen type. For CMV, QIAcube consistently produced the highest DNA recovery across all matrices, with particularly large differences in plasma and serum, where EZ1 and Maxwell RSC yielded significantly lower loads. The WNV results varied by matrix: EZ1 and QIAcube performed similarly in plasma, while Maxwell RSC achieved the highest RNA recovery in whole blood. While the QIAcube exhibited reduced WNV recovery in blood, it achieved the best performance in serum, as specified by the kit. No significant platform differences were observed for urine. Diluting whole blood reduced variability between platforms. Conclusions: Both sample matrix and extraction system strongly influence nucleic acid recovery. These results highlight the need for matrix-specific validation and standardized extraction approaches in molecular diagnostics. Full article

Background: West Nile Virus (WNV) is a mosquito-borne flavivirus responsible for seasonal outbreaks in temperate and tropical regions, including Europe, the Mediterranean, and the Middle East. Its transmission via mosquitoes, particularly Culex species, poses persistent challenges to public health. Despite ongoing efforts, comprehensive prevention and treatment strategies remain limited. Methods: A comprehensive search of peer-reviewed literature, clinical trials, and government surveillance data from Italy and Iran was conducted using PubMed, Scopus, Web of Science, and supplementary web-based resources. Inclusion criteria focused on molecular studies of WNV, vaccine and antiviral drug development, and regional outbreak reports. Results: WNV transmission is influenced by climatic conditions, as well as vector distribution and ecological patterns. While human vaccines are currently under development, only veterinary vaccines yielded promising but still limited evidence of effectiveness. Notably, therapeutic measures are currently limited to supportive care, whereas investigational antiviral drugs are in early-stage trials. Interestingly, Italy demonstrates robust surveillance with regular reporting of outbreaks, whereas data from Iran indicate that despite a widespread serological footprint, especially in southern and southwestern provinces, the reported clinical impact on humans and animals appears comparatively less severe. Conclusions: Bridging gaps in vaccine availability, therapeutic innovation, and disease monitoring is essential for effective WNV management to prepare for potential severe future outbreaks in Europe and the Middle East. On the other hand, regional differences between Italy and Iran reveal the need not only for tailored public health interventions and enhanced surveillance, but also for sustained investment in research. In our view, collaborative frameworks across Mediterranean and Middle Eastern countries in a “One Health” approach may improve preparedness and response to future WNV outbreaks. Full article