Forests are among the most biodiverse terrestrial ecosystems, in which small mammals play an important ecological role. Their presence is influenced by various habitat parameters, including vegetation structure, microclimate, food resources, and human-driven forest management practices. The aim of our study was to assess rodent diversity across different forests, with a particular focus on forest stand age and forest plant communities. For this purpose, we analyzed 17 years of forest rodent monitoring data across five forest plant communities. This study represents the first long-term monitoring results of small mammals in managed forests of continental Croatia. Trapping was conducted as part of routine rodent monitoring in state-owned forests, incorporating data collected from various research projects. The results showed that lowland forests, particularly floodplain oak forests, exhibited higher biodiversity compared to other forest plant communities. In addition, younger stands exhibited higher species richness than older stands. Canonical correspondence analysis (CCA) indicated that Microtus species were associated with lowland forests and younger stands. Overall, the findings demonstrate that both forest plant communities and stand age play important roles in shaping rodent diversity in continental Croatian forests. The obtained data provide a basis for optimizing forest management practices in continental forests.

Tick-borne diseases are a growing public health concern in the Mediterranean. Brijuni National Park (BNP), a unique, highly visited island ecosystem characterized by increased large game host density and diverse Mediterranean habitats, presents an elevated risk for pathogen co-circulation. This study addresses the lack of spatial and epidemiological data to accurately assess human exposure risk in this environment. We performed a detailed geospatial and epidemiological risk mapping of pathogen co-circulation in BNP. A total of 587 hard ticks were collected across 26 georeferenced micro-locations (2020-2022). Ticks were morphologically identified and subsequently screened for six key zoonotic bacterial pathogens using qPCR. The Minimal Infection Rate (MIR) and a Co-infection Rate (CR) were calculated. Geographic Information System (GIS) mapping was utilized to map ecological determinants of risk. Ixodes ricinus was the overwhelmingly dominant vector (94.0%), peaking in spring, with activity absent in summer. Recorded diverse tick fauna also included Hyalomma marginatum (3%), Haemaphysalis punctata (2%), Ixodes frontalis (0.8%) and Rhipicephalus sanguineus (0.2%). Active circulation of Borrelia burgdorferi s.l. (Bbsl), Anaplasma phagocytophilum, and Ehrlichia canis were confirmed. Bbsl presented the highest MIR (3.05). The Co-infection Rate (CR) was notably high at 29.41%, with triple co-infections (Bbsl, A. phagocytophilum, E. canis) concentrated in cultivated mosaics and holm oak forests (Quercus ilex L.). The highest number of ticks was recovered from ecotone zones, accounting for 50.0% of the total catch, confirming them as high-risk interfaces. The absence of Rickettsia conorii may be attributed to the strict control/absence of its primary host (domestic dogs). The presence of the exotic vector H. marginatum was also confirmed. The high rate of co-infection and the spatial concentration of risk in specific habitats underscore an elevated and complex public health risk in BNP, closely linked to habitat structure and increased game host density. This research provides an essential geospatial framework for targeted 'One Health' management, prioritizing vector control in ecotone zones and dense forest refugia. Urgent surveillance for the exotic H. marginatum is warranted to monitor the potential risk of Crimean-Congo Hemorrhagic Fever.

Leptospirosis is a worldwide zoonosis caused by pathogenic Leptospira spp. with small rodents serving as the main reservoir. In Croatia, the serogroup Pomona has been detected most frequently, but its genomic diversity remains insufficiently characterized. This study presents the first whole genome sequencing analysis of 48 Croatian Leptospira spp. isolates collected from small rodents over a 14-year period. Serological typing confirmed that all the isolates belonged to the serogroup Pomona. Genomic analysis assigned them to L. kirschneri based on high genomic similarity using average nucleotide identity (ANI). The isolates were assigned to ST-98 using traditional multilocus sequence typing (MLST), while cgMLST identified seven genotype clusters, many of which showed geographic structuring. Phylogenetic analyses based on single nucleotide polymorphisms (SNPs) supported this structure and revealed a monophyletic clade of Croatian isolates distinct from other global L. kirschneri strains. Serological typing, MLST, and phylogenetic clustering support classification of the isolates as L. kirschneri, serogroup Pomona, most likely serovar Mozdok, although serovar Tsaratsovo cannot be excluded. These results indicate the existence of a geographically restricted and potentially host-adapted lineage of L. kirschneri in Croatia. The integration of ecological, serological, and genomic data in this study emphasizes the value of whole genome sequencing for understanding the population biology of Leptospira spp. serogroup Pomona. Moreover, it supports targeted, country-specific surveillance and control strategies for leptospirosis through the identification of circulating serovars and species in reservoir hosts, in line with a One Health approach.

Neuroinvasive arboviruses such as tick-borne encephalitis virus (TBEV), West Nile virus (WNV), Usutu virus (USUV), and Toscana virus (TOSV) have (re-)emerged with increasing incidence and geographic range. We analyzed the epidemiology of arboviral infections in Croatia during the 2024 transmission season. A total of 154 patients with neuroinvasive diseases (NID), 1596 horses, 69 dead birds, and 7726 mosquitoes were tested. Viral RNA was detected using RT-qPCR. IgM/IgG-specific antibodies were detected using commercial ELISA or IFA, with confirmation of cross-reactive samples by virus neutralization test. RT-qPCR-positive samples were Sanger sequenced. Arboviral etiology was confirmed in 33/21.42% of patients with NID. WNV was most frequently detected (17/11.03%), followed by TBEV (10/6.49%), USUV (5/3.24%), and TOSV (1/0.64%). WNV infections were reported in regions previously known as endemic, while in one continental county, WNV was recorded for the first time. USUV infections re-emerged after a six-year absence. In addition to human cases, acute WNV infections were recorded in 11/395 (2.78%) of horses and two dead crows. WNV IgG seropositivity was detected in 276/1168 (23.63%) and TBEV IgG seropositivity in 68/428 (15.88%) horses. None of the tested mosquito pools were positive for WNV and USUV RNA. Phylogenetic analysis showed the circulation of WNV lineage 2 and Usutu Europe 2 lineage. Climate conditions in 2024 in Croatia were classified as extremely warm, which could, at least in part, impact the quite intense arboviral season. The spreading of flaviviruses in Croatia highlights the need for continuous surveillance in humans, animals, and vectors (“One Health”).

Due to the evident increase in tick-borne diseases worldwide, it is necessary to constantly update information on the distribution and zoonotic potential of hard ticks. We studied diversity, population structure, and seasonal dynamics of hard tick fauna, faunal similarity and the climate impact on tick occurrence in natural habitats (NHs) (forest communities) and anthropogenic habitats (AHs) (orchards, grasslands, degraded forests) in eastern and central parts of Continental Croatia. Host-seeking hard ticks were sampled by the flag-dragging method in lowland AHs (Bansko Hill (BH); 2023–2024 yr.) and in mountainous NHs (Medvednica Mountain (MM); 2019–2021, 2024 yr.). Overall, 2726 specimens belonging to eight hard tick species (Ixodes ricinus, I. frontalis, I. hexagonus, I. kaiseri, Haemaphysalis inermis, H. concinna, Dermacentor marginatus, D. reticulatus) were identified in AHs, while in NHs 1543 hard ticks, belonging to three species (I. ricinus, I. frontalis, D. reticulatus), were collected. The most abundant species in both habitat types (47.83% in AHs, 99.80% in NHs) was I. ricinus, showing unimodal seasonal activity within studied NHs and bimodal activity at AHs. Comparison of hard tick fauna in different habitats using the Sørenson index on BH and MM showed a high percentage of similarity (50.0–88.8). At AHs, a significant (p < 0.05) negative correlation was determined between the abundance (N) and the mean monthly air temperatures (°C) for H. inermis (r = −0.5931; p = 0.0421) and D. reticulatus (r = −0.6289; p = 0.0285), while their numbers positively correlated (r = 0.5551; p = −0.2667; r = 0.4430; p = 0.1492) with air humidity (%). In contrast, the number of sampled host-seeking I. ricinus ticks at natural forest habitats on MM was positively associated with air temperature and negatively with air humidity at elevations from 200 to 1000 m a.s.l. (r = −0.7684; p = 0.0259; at 200 m a.s.l.). Collected specimens of I. frontalis mark the first record for Osijek–Baranja County, while the sampled D. reticulatus on MM represents the first catch at 1000 m a.s.l. in Croatia. This new data on the distribution and seasonality of medically important hard tick species in Continental Croatia contributes to identifying tick-risk foci and high-risk periods.

Tick-borne encephalitis (TBE) is a common arbovirus infection in Croatia. The aim of the study was to analyse 17 years of data on TBE seroprevalence and acute TBE cases in correlation with winter temperature, precipitation and wildlife abundance to identify possible patterns that may be predictive indicators of TBE incidence. Clinical diagnosis of TBE was confirmed by determining IgM and IgG anti-TBE antibodies. Of the 19,094 analysed patients, 4.2% had acute TBE, significantly more often in older age (p < 0.001) and male gender (p < 0.001). Overall seroprevalence of TBE among the tested population was 5.8% and varied annually from 2.8% to 10.7%. The mean acute TBE incidence rate was 1.1/100,000 population with significant regional differences: 1.7/100,000 in the continental vs. 0.2/100,000 and 0.5/100,000 in the Mediterranean and Alpine regions, respectively. A particularly high incidence of 3.1/100,000 was recorded in northern Croatia. TBE displayed a seasonal pattern, peaking in June and July. Moderate negative correlations were observed between TBE acute cases and winter temperatures from December to February (r = -0.461; p = 0.062), relative rodent abundance (r = -0.414; p = 0.098) and yearly precipitation from one year before (r = -0.401; p = 0.123). The analysis showed that more acute TBE cases are recorded after a warmer winter and a negative correlation between the abundance of forest Apodemus sp. and the number of TBE cases in the same year.

Praćenje prisutnosti vektora zaraznih bolesti od ključne je važnosti za očuvanje javnog zdravlja te dodatno naglašava potrebu za interdisciplinarnim pristupom u okviru koncepta „Jedno zdravlje” (engl. One Health). Ovaj rad temelji se na terenskom istraživanju krpelja kao vektora zoonotskih patogena te analizi pojavnosti krpeljima prenosivih bolesti na području Istarske županije. Podaci Hrvatskog zavoda za javno zdravstvo za razdoblje od 2016. do 2023. godine ukazuju na ukupno 126 prijavljenih slučajeva zoonotskih bolesti, od čega 114 (93,4 %) slučaja lajmske borelioze, dva slučaja Q-groznice te po jedan slučaj rikecioze i hemoragijske vrućice s bubrežnim sindromom. Osam prijavljenih slučajeva zoonoza bilo je evidentirano kod nerezidenata Istarske županije. U okviru istraživanja provedeno je sustavno uzorkovanje tvrdih krpelja (Acari; Ixodidae) u razdoblju od 2020. do 2023. godine metodom krpeljne zatege i prikupljanjem s domaćina, pri čemu je prikupljeno ukupno 2349 jedinki koje pripadaju 12 različitih vrsta iz rodova Ixodes, Dermacentor, Hyalomma, Haemaphisalis i Rhipicephalus<7i> te jedan meki krpelj iz roda Argas . Dominantna vrsta bila je obični ili šumski krpelj ( Ixodes ricinus L.) (70,84 %), poznat vektor bakterija Borrelia burgdorferi sensu lato (uzročnik lajmske borelioze) i Coxiella burnetii (uzročnik Q-groznice). Rezultati ukazuju na izraženu prisutnost i raširenost vektora odgovornog za prijenos lajmske borelioze, koja je potvrđena kao najzastupljenija zoonoza u regiji. Dobiveni podaci potvrđuju potrebu za kontinuiranim entomološkim nadzorom i epidemiološkim praćenjem vektorski prenosivih bolesti u svrhu bolje procjene rizika i donošenja javnozdravstvenih mjera.

Tick-borne encephalitis (TBE) is the most significant arboviral infection in Croatia. The aim of the study was to analyse and correlate 17-year TBE seroprevalence data with winter temperature, precipitation and wildlife abundance to identify possible patterns that can be predictive of TBE incidence. TBE diagnosis was based on IgM/IgG anti-TBE antibodies and individual clinical interpretation of the results. Of the 19,094 analysed patients, 4.2% had acute TBE, significantly more often in older age (p<0.001) and in men (p<0.001). Overall seroprevalence of TBE among the tested population was 5.8%, and varied annually from 2.8% to 10.7%. The mean acute TBE incidence rate was 1.1 per 100.000 population with significant regional differences: 1.7 in the continental vs. 0.2 and 0.5 in the Mediterranean and Alpine regions, respectively. Particularly high incidence of 3.1 was recorded in northern Croatia. TBE displayed a seasonal pattern, peaking in June and July. Moderate negative correlations were observed between TBE acute cases and winter temperatures from December to February (r=-0.461; p=0.062), relative rodent abundance (r=-0.414; p=0.098) and yearly precipitation from one year before (r=-0.401; p=0.123). Considerable efforts are needed to understand the impact on TBE incidence to improve disease prevention.

Tick-borne encephalitis (TBE) represents an important public health problem in Europe. We analyzed the epidemiology of TBE based on data from humans, animals, and Ixodes ricinus ticks in endemic regions of continental Croatia. In the period from 2017 to 2023, cerebrospinal fluid (CSF) and serum samples of 684 patients with neuroinvasive diseases, 2240 horse serum samples, and 300 sheep serum samples were tested for TBEV. In addition, 8751 I. ricinus ticks were collected. CSF samples were tested using RT-PCR. Serological tests (serum, CSF) were performed using commercial ELISA, with confirmation of cross-reactive samples by a virus neutralization test. Eighty-four autochthonous human TBEV cases were confirmed. The majority of patients were in the age group of 40–69 years (58.3%) with a male predominance (70.2%). TBE showed a bimodal seasonality with a large peak in April–August and a small one in October–November. In addition to humans, TBEV IgG antibodies were found in 12.2% of horses and 9.7% of sheep. Seasonal tick abundance corresponds to the reported number of human infections. Continental Croatia is still an active natural focus of TBE. Continuous monitoring of infections in humans, sentinel animals, and ticks is needed for the implementation of preventive measures.

Sitni glodavci (Rodentia, Murinae: pravi miševi, Arvicolinae: voluharice) uvelike pridonose održavanju ravnoteže i raznolikosti šumskih zajednica. Jednako tako oni mogu biti uzročnici otežane prirodne obnove šuma, ali i rezervoari te prijenosnici brojnih uzročnika zoonoza, bolesti prijetećih za zdravlje ljudi te domaćih i divljih životinja. Iako od početka 1980-ih godina dominantna metoda kontrole brojnosti glodavaca u državnim šumama uključuje primjenu rodenticida, sve se veća pažnja pridaje sustavnomu monitoringu glodavaca, prevenciji šteta i primjeni bioloških metoda zaštite. U ovom je istraživanju testiran učinak primjene tzv. T-stajališta (N = 4 kom.) na primamu pernatih predatora sitnih glodavaca te na smanjenje šteta od glodavaca na pomladnoj površini sastojine poljskoga jasena (Fraxinus angustifolia Vahl.) u Šumariji Kutina, u razdoblju od listopada 2023. do rujna 2024. godine. Pregledom 213 videosnimki te 17 881 fotografije zabilježeno je ukupno 126 slijetanja šest vrsta ptica, od kojih je 114 (91,47 %) doleta bilo vezano uz tri ptičje vrste (šumska sova /Strix aluco/, škanjac mišar /Buteo buteo/ i rusi svračak /Lanius collurio/), koje se više-manje prehranjuju sitnim glodavcima. Da je primjena T-stajališta pomogla smanjenju šteta od glodavaca, razvidno je iz usporedbe broja sadnica poljskoga jasena čiju su koru nagrizli glodavci, što je u najvećem omjeru (30,23 %) zabilježeno na kontrolnoj plohi, bez sletnoga mjesta, dok je manji udio (13,95 % i 6,98 %) zabilježen na dvjema plohama na koje su te ptičje vrste dolijetale. Iako ne statistički značajna, umjereno jaka negativna korelacija (r(3) = –0,57, p < 0,05) utvrđena je između broja doleta šumske sove te broja nagrizenih jasenovih sadnica. Dobiveni rezultati govore u prilog pozitivnomu učinku ove biološke kontrole glodavaca, koja, osim što je ekonomična, može pridonijeti uspjehu pomlađivanja šuma uz minimalan utjecaj na okoliš. Preporučuje se daljnje testiranje primjenjivosti T-stajališta i u drugim tipovima šumskih zajednica.

Small rodents (Rodentia, subfam. Murinae: real mice, Arvicoline voles) greatly affect natural regeneration, stability and dynamics of forest communities worldwide. Every 3–4 years rodent damage in Croatian state forests is the most severe in forest regeneration stands, especially in pedunculate oak (Quercus robur L.) and narrow-leaved ash (Fraxinus angustifolia Vahl.) forests, where rodents can seriously impede natural regeneration by damaging seeds, stems and roots of saplings. These negative interactions are an even bigger challenge nowdays as pedunculate oak and narrow-leaved ash have become more vunerable in the last decades and are known as the most sensitive species of lowland forests in Croatia due to microclimatic and macroclimatic changes and the unfavourable interaction of a whole series of anthropogenic, abiotic and biotic factors. In the last 40 years, in Croatian state forests, rodent management consisted of monitoring and mainly rodenticide use. Trying to implement IPM (Integrated Pest Management) postulates into practice over the years, different prevention methods against small rodents were tested, but not many came to use. The aim of this research was to look into different logging residue management approaches and their effect on the rodent damage in two pedunculate oak forest regeneration stands in central Posavina in Croatia. Rodent damage on stem and root of tree saplings was recorded by visual inspection on three plots (5x5 m) with scattered logging residue, and one plot (5x5 m) with no residue at one micro-depression site (95 m a.s.l.), and on one micro-elevation (99 m a.s.l.) site. Plots with scattered logging residue represented a type of forest residue management in which logging debris (branches) is cut to smaller lengths and distributed evenly at the forest regeneration stand. Plot with no logging debris represented a residue management method in which wood mass is completely removed from the regeneration stand after felling. We counted, determined and inspected tree saplings found at chosen plots for rodent damage (on stem and roots) and also determined the average weight and moisture content of logging residue (branches around 5–7 cm in diameter) found at the site. In spring 2017, 3380 tree saplings (2978; 81% pedunculate oak, 7; 0.2% narrow-leaved ash and 395; 11.7% other deciduous species) were inspected for rodent damage. At micro-depression site, on a plot with no logging residue, only 13.4% of the saplings were damaged, while the average share of damaged saplings on three plots with scattered residue was more than six times higher; 87.8%. The average mass of the logging residue weighed at site with scattered residue was 10.14 kg kg/m2 and moisture content was 19.2%. At micro-elevation site, 25.4% of the saplings were damaged on a plot with no logging residue, while the average share of damaged saplings on three plots with scattered residue was two times higher; 51.4%. The average mass of the logging residue weighed at SRP 1–3 was 5.1 kg/m2. We also determined moderately strong positive correlation (R=0.69133) between the mass of logging residue and rodent damage and strong negative correlation (R=–0.89598) between wood moisture content of the logging residue and rodent damage. In years ahead, with unpredictable climate effects and potentially very variable small rodent dynamics, removing the logging residue after the felling could represent a residue management that contributes to a more effective and ecologically based rodent management. It could also become a usable preventive method within IPM and help prevent sever rodent damage, even during the outbreaks in pedunculate oak regeneration stands.

Altitudinal distributions, population structures and seasonal dynamics of tick fauna at three localities in Continental Croatia (Medvednica and Papuk) and an alpine biogeographic region (Gorski Kotar) were studied. Sampling of questing ticks was performed twice a year (spring and autumn, from 2019 to 2021) at different altitudes (200, 400, 600, 800 and 1000 m above sea level) using the flagging method. In total, 2942 ticks (53.9% larvae, 40.1% nymphs, 6.0% adults) were sampled and 2937 (99.83%) were determined as Ixodes ricinus, 4 (0.14%) as Haemaphysalis concinna and 1 (0.03%) as Ixodes frontalis. Ixodes ricinus was the only species found at all altitudes and sampling sites. The highest tick abundance was recorded at higher altitudes (800–1000 m asl.) on Medvednica and in Gorski Kotar within mixed forests of European beech and European silver fir, while on Papuk most of the ticks were sampled at lower altitudes (200 m asl.) in Sessile oak forest. From 27 pools containing 305 ticks, 1 (3.7%) was positive for Borrelia burgdorferi sensu lato infection. Borrelia burgdorferi s.l. was detected in 20% (1/5) of the pools containing nymphs and adults collected in Gorski Kotar (600 and 800 m asl.). Sequencing of the ospA gene and phylogenetic analysis revealed the presence of the Borrelia burgdorferi sensu stricto genotype.

Female as well as male mate choice has already been recognized in many insects. The traits responsible for the mate choice in a striped stink bug (Graphosoma lineatum L.) are not yet explored. This works concentrates on few possible traits responsible for mate choice in a striped stink bug. For this analysis free living copulating individuals as well as the single ones were collected. On two different locations animals were collected and their body length, pronotum broadness and coloration were measured. No differences were found in all measured traits between copulating and control individuals, showing no preferences when choosing copulation partner. Results also show no evidence of assortative mating, referring to the body length and the pronotum broadness of both sexes. All three measured traits seem not to have an influence on the mate choice of both sexes. Further experimental testing is needed to fully excluded importance of body size and coloration in mate choice of a striped stink bug.

Molecular methods are increasingly being utilized for accurate identification of ticks (Acari: Ixodidae), especially in cases of morphologically highly similar species. In this study, we performed molecular research of the tick fauna in Croatia using DNA barcoding method. Ticks were sampled in three biogeographical regions and thirteen species were recorded: Dermacentor marginatus, Dermacentor reticulatus, Haemaphysalis concinna, Haemaphysalis inermis, Haemaphysalis punctata, Hyalomma marginatum, Ixodes frontalis, Ixodes hexagonus, Ixodes kaiseri, Ixodes ricinus, Rhipicephalus bursa, Rhipicephalus sanguineus s.l. and Rhipicephalus turanicus. Ixodes kaiseri is for the first time recorded in the fauna of Croatia. Of the thirteen hard tick species analyzed in this study, pathogens from different groups (bacteria, protozoa and viruses) have been detected in eight species in Croatia so far. For the important vector species R. sanguineus s.s., new distributional data for Croatia are given. The standard COI barcoding region was amplified, and the sequences were analyzed by species delimitation methods together with the sequences of conspecific and congeneric species from the public BOLD database. Our specimens of H. punctata represent a new, genetically distinct MOTU. A brief overview of the available public DNA barcoding data for Ixodidae is presented, highlighting the need for an integrative approach for the clarification of the taxonomic status of problematic Ixodid taxa. The results provide a basis for the establishment of a molecular data platform for the Ixodidae of the Croatian fauna.

Tick-borne diseases are a serious threat to both public and veterinary health. In this study, we used high-throughput sequencing to characterize the virome of three tick species implicated in the spread of vector-borne disease throughout Croatia. Ten viruses were identified, including seven potential novel species within the viral families Flaviviridae, Nyamiviridae, Rhabdoviridae, Peribunyaviridae, Phenuiviridae, and Nairoviridae.

Several arboviruses have emerged in Croatia in recent years. Tick-borne encephalitis is endemic in continental counties; however, new natural micro-foci have been detected. Two autochthonous dengue cases were reported in 2010. West Nile virus emerged in 2012, followed by emergence of Usutu virus in 2013. Although high seroprevalence rates of Toscana virus have been detected among residents of Croatian littoral, the virus remains neglected, with only a few clinical cases of neuroinvasive infections reported. Lymphocytic choriomeningitis virus is a neglected neuroinvasive rodent-borne virus. So far, there are no reports on human clinical cases; however, the seroprevalence studies indicate the virus presence in the Croatian mainland. Puumala and Dobrava hantaviruses are widely distributing rodent-borne viruses with sporadic and epidemic occurrence. Hepatitis E virus is an emerging food-borne virus in Croatia. After the emergence in 2012, cases were regularly recorded. Seropositivity varies greatly by region and population group. Rotaviruses represent a significant healthcare burden since rotavirus vaccination is not included in the Croatian national immunization program. Additionally, rotaviruses are widely distributed in the Croatian ecosystem. A novel coronavirus, SARS-CoV-2, emerged in February 2020 and spread rapidly throughout the country. This review focuses on emerging and neglected viruses of zoonotic importance detected in Croatia.

As tick-borne disease incidence and distribution is increasing worldwide, there is a true need for better understanding of the distributional ecology of their vectors. The aim of this study was to determine the diversity of hard ticks fauna (Acari: Ixodidae) and their seasonal dynamics in different habitats at three urban recreational sites in Croatia’s capital, the City of Zagreb, known as the natural foci of Lyme borreliosis and tick borne encephalitis. Within a three-year period (2016 - 2018), the only species detected was Ixodes ricinus Linnaeus, 1758. Using flag dragging method 506 ticks were sampled; 273 (54%) in their nymphal stage, 166 (33%) as larvae and 64 (13%) as adults. The highest abundance of ticks was recorded at forest habitat. Seasonal activity showed their peaks at midspring and midsummer. Continuous monitoring of hard tick population in urban areas should and could become a standard method of tick-borne diseases prevention.

In June 2019, the Croatian Institute of Public Health was informed of a cluster of patients with laboratory confirmed tick-borne encephalitis (TBE) from the Gorski Kotar region. Five of the six patients with TBE reported consuming raw (unpasteurized) goat milk in the two week period before symptom onset, and one reported a recent tick bite. To assess risk factors for infection, we selected six control individuals from among healthy family and community members, and conducted a case-control analysis. None of the cases or controls were vaccinated against TBE. Individuals with TBE (cases) had 25 (95 % CI 0.8-1410.2, p = 0.021) times higher odds of raw goat milk consumption compared to healthy controls. Milk samples from 12 goats from the implicated farm were tested for the TBE virus (TBEV) using RT-PCR. TBEV RNA was not detected in the milk, but serological testing of goats and other farm animals yielded evidence of exposure to the virus: Six goats from the flock had TBEV neutralizing antibodies. Our findings suggest that the vehicle for the outbreak was raw goat milk from a single farm. Following public health advice to cease consumption of raw dairy products, no further cases have been reported.

Since the role of wild rodents/small mammals in hepatitis E virus (HEV) epidemiology has been a subject of considerable debate, this study was conducted to investigate the potential presence of HEV RNA in small rodents collected within their natural habitats and to detect if they can be potential reservoirs of the virus. A total of 483 small rodents were captured using snap traps placed at 11 regions in Croatia. Sampling was undertaken in 2008 and repeated from 2010 to 2014. Liver samples were tested for the presence of HEV RNA. HEV RNA was detected in only one liver sample (0.21%) originated from Apodemus flavicollis from the location Medvednica, nearby Zagreb collected in 2014. According to the sequence analysis, the isolate has shown to be a member of Orthohepevirus A species, genotype HEV-3. The genotyping results confirmed grouping into subtype 3a, general cluster 3abchij.The detected HEV strain showed to be genetically highly related to strains found in humans and/or domestic pigs and wild boars from Croatia. Our finding indicates that wild small mammals could play a role in the epidemiology of HEV-3 infection and therefore should be taken under consideration as potential reservoirs or/and transmitters of the disease. However, further investigation is needed to recognize their potential for maintaining the infection in natural conditions.