Ixodid ticks are distributed across all countries of the Western Balkans, with a high diversity of species. Many of these species serve as vectors of pathogens of veterinary and medical importance. Given the scattered data from Western Balkan countries, we have conducted a comprehensive review of available literature, including some historical data, with the aim to compile information about all recorded tick species and associated zoonotic pathogens in this region. Based on the collected data, the tick fauna of the Western Balkans encompasses 32 tick species belonging to five genera: Ixodes, Haemaphysalis, Dermacentor, Rhipicephalus and Hyalomma. A range of pathogens responsible for human diseases has also been documented, including viruses, bacteria and parasites. In this review, we emphasize the necessity for integrated surveillance and reporting, urging authorities to foster research by providing financial support. Additionally, international and interdisciplinary collaborations should be encouraged that include the exchange of expertise, experiences and resources. The present collaborative effort can effectively address gaps in our knowledge of ticks and tick-borne diseases. Graphical Abstract

Background: Dirofilariosis is a parasitic mosquito-borne disease caused by members of the genus Dirofilaria, which includes Dirofilaria immitis and Dirofilaria repens. Surveillance studies in Europe have revealed that D. immitis can also be detected in a range of wild carnivores, raising questions over the impact of infections on wild carnivore animal health but also whether these populations may act as a reservoir for infection of other species, including domestic dogs and humans. Methods: In the current study, we conducted surveillance for the presence of D. immitis in several wild carnivore species, including golden jackals (Canis aureus; n = 77), red foxes (Vulpes vulpes; n = 326), and European badgers (Meles meles;n = 28), collected during an annual rabies surveillance and control program from across continental and coastal regions of Croatia. Results: Macroscopic examination of the right chambers of the heart during a post-mortem examination resulted in the detection of filarial parasites in 6.5% (5/77) golden jackal carcasses. Morphological identification, confirmed by molecular screening, classified all parasites as D. immitis. No D. immitis were detected in the red foxes or European badgers examined. All infected golden jackals were adults aged from 2 to 7 years with a parasite load ranging from 2 to 7 nematodes per carcass. One animal was infected with a sexually mature pair, while a second harbored pre-mature parasites; the remaining positive jackals were infected with female parasites only. Notably, histological examination of cardiac and lung tissue revealed proliferative endarteritis in the jackal with the highest parasite burden. Conclusions: Further studies are required to establish whether golden jackals, as well as other wild carnivore hosts, may serve as competent definitive hosts of D. immitis and act as reservoirs for infection of other species including domestic dogs and humans. Histological changes in the cardiac tissue of at least one positive jackal were suggestive of infection with pathological consequences for the host. Graphical

Sarcocystis spp. (Apicomplexa: Sarcocystidae) are globally distributed protozoan parasites with an obligatory two-host prey–predator life cycle involving intermediate (IHs) and definitive hosts (DHs). Canids, including the red fox (Vulpes vulpes), often serve as DHs for species infecting various ungulates. This study identified Sarcocystis species in red foxes from Croatia, Lithuania, and Portugal. Between 2021 and 2024, 164 faecal samples (80 from Croatia, 50 from Portugal, and 34 from Lithuania) were analysed using nested PCR targeting the cox1 gene. Twelve Sarcocystis species were detected: S. arieticanis, S. capracanis, S. capreolicanis, S. cruzi, S. gracilis, S. hjorti, S. iberica, S. linearis, S. miescheriana, S. morae, S. rossii, and S. tenella. The overall prevalence was highest in Croatia (78%) and Lithuania (62%) and lowest in Portugal (30%). Phylogenetic and haplotype analyses revealed high homogeneity and absence of geographic structuring. These results confirm the red fox as a key DH for multiple Sarcocystis species infecting European ungulates and underscore its epidemiological importance in parasite transmission across diverse ecosystems.

The infestation of ruminants by fly larvae of the Oestridae family can lead to nasopharyngeal or subcutaneous myiasis, which can harm animal welfare and productivity on sheep and cattle farms. The infestation of wild ruminants allows them to serve as reservoirs for subsequent transfer to domestic animals. The fly species most commonly responsible for myiasis have been well studied in many parts of the world, but less so in southeastern Europe. Here, we identified three botfly species among 197 subcutaneous larvae and 138 nasopharyngeal larvae from 36 wild roe deer (Capreolus capreolus) and 9 wild red deer (Cervus elaphus) at 30 locations across Croatia. Instars were stored in 75% ethanol and their species and developmental stage were identified based on morphological and morphometric keys. Subcutaneous larvae in both cervid species were identified as Hypoderma diana, while nasopharyngeal larvae were identified as Cephenemyia simulator in roe deer and Pharyngomyia picta in red deer. Partial sequencing of the gene-encoding mitochondrial cytochrome oxidase subunit I confirmed the taxonomic classification of C. stimulator and P. picta but was unable to confirm that of H. diana for lack of previously published sequences. This study appears to be the first to combine the morphological and molecular characterization of myiasis-causing botflies in wild cervids in southeastern Europe.

Ixodid ticks are present throughout the Western Balkan countries, including Albania, Bosnia and Herzegovina, Croatia, Montenegro, North Macedonia and Serbia, with many species serving as vectors for pathogens of both veterinary and medical importance. We have conducted a thorough examination of existing literature, encompassing historical documents, to collect information on all documented non-zoonotic tick-borne pathogens found in ticks, pets, farm animals and wild animals across the Western Balkan region. A comprehensive review was necessary due to the scarcity and scattered nature of available data from this area. The tick fauna in the Western Balkans consists of 32 species across five genera: Ixodes, Haemaphysalis, Dermacentor, Rhipicephalus and Hyalomma. Various pathogens responsible for diseases in animals, including bacteria and parasites, have also been documented, many of which can cause important diseases and significant reductions in animal productivity. Initial efforts were directed towards pathogen surveillance and the characterisation of non-zoonotic tick-borne pathogens, resulting in the identification of Theileria orientalis, Anaplasma bovis and Anaplasma marginale in cattle, although significant gaps remain in the current research. Studies on small ruminants have been sparse, with confirmed cases of Anaplasma ovis and Babesia ovis in sheep, but no comprehensive and systematic research on pathogens in goats. In contrast, research on canine piroplasms has identified several species, including Babesia canis and Babesia vulpes. Studies on wild animals, however, have predominantly focused on wild canines and carnivores, with limited attention given to non-zoonotic pathogens. Notably, only one study has reported non-zoonotic tick-borne pathogens in artiodactyl species and wild felids. This review is a much needed overview of existing research on non-zoonotic tick-borne diseases in the Western Balkans, including the historical context, current data and research gaps. Given the significant impact of these diseases on animal health and productivity, as well as their potential biodiversity, further comprehensive studies and the establishment of national surveillance systems for tick-borne diseases are essential for a better understanding and mitigation of their impact. Graphical abstract

We report the first confirmed case of persistent microfilaremia in a human host infected with Dirofilaria repens. A 54-year-old woman from an endemic area in Croatia presented with peripheral eosinophilia and dermatological symptoms. Over four months, microfilariae were repeatedly detected in her blood using thick smears and Knott’s test, and the diagnosis was molecularly confirmed via COI gene sequencing and detection of Wolbachia endosymbionts. This case provides compelling evidence that D. repens can sustain a complete or near-complete life cycle in humans under specific conditions. Our findings have significant implications for clinical diagnostics, One Health surveillance, and public health interventions.