BACKGROUND: West Nile virus (WNV) has become established across Europe, with Hungary serving as a key transmission hub since 2004. Following reduced activity during 2020–22, the 2024 season marked a resurgence with the largest geographical distribution ever recorded in Europe. AIM: To analyse the 2024 WNV transmission season in Hungary using a One Health approach and characterise circulating strains within the European phylogeographic context using comprehensive genomic surveillance. METHODS: Complete and near-complete genome sequencing was performed on 55 specimens from 38 humans, 15 birds and two Culex pipiens mosquito pools using amplicon-based next-generation sequencing. Phylogeographic analysis incorporated 637 European WNV genome sequences (2004–24) with time-scaled Bayesian phylogenetic reconstruction and continuous spatial diffusion modelling. RESULTS: Hungary reported 113 human WNV cases in 2024 (n = 111 autochthonous, 2 imported), a 3.7-fold increase from 2023 (incidence: 1.16 vs 0.31 per 100,000 population). Neuroinvasive disease predominated (92%, n = 104) with a 7.9% case fatality rate. All 55 sequenced strains belonged to WNV lineage 2. Phylogeographic analysis revealed Hungary's central role in European WNV dissemination since 2004, with multiple introductions and local diversification across distinct clades. Continuous spatial modelling identified Hungary as a persistent transmission hub with bidirectional viral flow to neighbouring countries, contributing to northward expansion. CONCLUSION: Hungary remains a critical WNV transmission hub in Central Europe with established endemicity of multiple lineage 2 clades. The analysis highlights Hungary's role as both a recipient and major source of European WNV diversity, emphasising the need for coordinated surveillance and climate-adapted preparedness strategies.

A sudden mass mortality involving 44 fallow deer ( Dama dama ) occurred in September 2020 at a game management area near Budapest, Hungary. The die-off affected both sexes and all age classes equally. On postmortem examination of 2 subadults and 1 fawn, we found average body condition, diffuse subcutaneous edema, swelling of peripheral lymph nodes, marked hemorrhages in lymph nodes along the esophagus and trachea, and left ventricular dilation. We isolated Pasteurella -like colonies from spleen, liver, small intestine, lung, and brain samples of 7 animals, and identified them as P. multocida serotype B:2 by amplifying kmt1 , tox A, and hyaC-hyaD genes, capsular typing by PCR, and serotyping by agar gel diffusion precipitation test, which established the diagnosis of hemorrhagic septicemia as the cause of the outbreak. By further analysis, we determined that all of our P. multocida isolates encoded ptf A, fim A, hsf -2, nan H, hgb A, and pfh A, but we did not detect genes encoding tox A, hsf -1, tbp A, or tad D. We identified our strains by RIRDC MLST as sequence type (ST)122, characteristic for strains causing hemorrhagic septicemia, while using multi-host MLST analysis we assigned these strains to ST64 clustering with P. multocida strains from the 2015 hemorrhagic septicemia outbreak of saiga antelopes in Kazakhstan. We concluded that increased population density and aggregation due to limited drinking water availability played a role in initiating the outbreak.

For centuries, the most prevalent antler abnormalities observed worldwide have been attributed to trauma. However, detailed pathological investigation of these cases has not yet been carried out. In free-living fallow deer (Dama dama), we identified a chronic osteomyelitis-like condition—Pedunculitis Chronica Deformans (PCD)—using pathological and radiological diagnostics. We propose that inflammation during post-casting wound healing and consequent scar formation can trigger the development of PCD. In this study, we characterize the pathomorphology of PCD and introduce a scoring system to describe its severity. Furthermore, we describe the histoanatomy of the junction between the pedicle and the surrounding skin—an area essential for the integrity of the integument—which, when compromised, may predispose cervids to PCD. Our findings suggest that the most common antler abnormality results from a pathological fracture associated with PCD, which can be further complicated by fatal meningoencephalitis and brain abscesses. PCD-related lesions, while less frequently observed, can also be identified in roe deer (Capreolus capreolus) and red deer (Cervus elaphus), with species-specific differences. These findings overlap with cases reported in other cervid species, suggesting a more general disorder of antler formation. Describing this condition provides a basis for assessing its epidemiology and understanding its relevance to wildlife health.

Several Blankaartia acuscutellaris (Walch, 1922) specimens were collected from 15 bird species in Hungary. This is the first report the trombiculids from birds in Hungary and this is the first record of B. acuscutellaris on Eurasian Wren, Common Starling, Eurasian Tree Sparrow, Wood Sandpiper, Eurasian Blackcap, Blue Tit and Little Bittern. The first list of the chiggers (Trombiculidae) occurring in Hungary is also presented.

Parasitic skin mites associated with wild birds are understudied members of host–parasite systems in Europe despite their ecological importance, potential role as disease vectors, and effects on host fitness. Using a multidisciplinary approach combining faunistic, ecological, and molecular methods, this study investigated two mite species that parasitize passerine birds in Hungary, Harpirhynchus dusbabeki and Blankaartia acuscutellaris. Birds were examined during field sampling conducted between 2022 and 2024 at bird ringing stations and through a nationwide volunteer bird-ringing network. Parasites were identified morphologically, prevalence patterns were analyzed statistically, and mitochondrial genetic data were used to assess phylogenetic relationships. The occurrence of H dusbabeki was recorded in Hungary for the first time, and its host spectrum was found to extend to multiple host species beyond its previously known primary host, the Bearded Reedling. Blankaartia acuscutellaris infested several passerine species, with a significantly elevated prevalence in Bearded Reedlings and markedly higher prevalence among juveniles. Genetic analyses revealed close relatedness between the Hungarian and Slovakian populations of B. acuscutellaris, but showed distinct genetic separation from morphologically identified conspecifics from Laos, Asia. These findings improve the understanding of mite–passerine associations in Central–Eastern Europe and highlight the value of integrating ecological and molecular approaches to reveal the patterns of host exploitation and geographic differentiation in parasitic mites.