INTRODUCTION: Human population growth and increasing exploitation of natural resources have caused changes in ecological conditions for different species of wildlife. Many of these species have adapted to living near humans, i.e. to living in urban habitats using a variety of anthropogenic resources for survival. Typical adjustments include increasing social groups and increasing population density, reducing living space, and changing eating habits. Members of the marten family (Mustelidae), such as the beech marten (Martes foina), are examples that show remarkable flexibility in finding shelter and food in human settlements and dwellings, and even in breeding in urban cores. In several European countries, progressive migration and placement of the beech marten (Martes foina) in urban areas has been recorded. Negative aspects of the growing number of wild animals in the cities include the increased risk of transmitting infectious diseases, possible attacks on humans and domestic animals, property damage and traffic accidents. In addition, changes in social relations are the reason for greater agglomeration of individuals in a small area and maintenance of close contact among members of the same species, which increases the risk of maintaining and transmitting certain pathogens in urban and suburban areas. The above-mentioned, as well as the fact that a large number of zoonotic diseases are known in wild carnivores, indicates the need to monitor wildlife population in order to assess current health status and predict the role in disease transmission. REVIEW OF THE LITERATURE: The marten family appeared in the late Eocene and early Oligocene periods when members of this family inhabited Europe and North America. Their migrations to the south of the continents were recorded first in Africa during the early Miocene and then in South America in the Quaternary. The marten family consists of five subfamilies: Mustelinae (weasels, minks, ferrets and martens), Melliovorinae (honey badger), Melinae (badgers), Mephitinae (American ferrets) and Lutrinae (otters). According to the usual classification, the beech marten (Martes foina) is classified as a mammal of the order Carnivora, the family of marten (Mustelidae) and the subfamily of marten (Mustelinae). The genus marten (Martes) consists of 7 species, most of which are animals of tropical, temperate and boreal forest zones of North America, Europe and Asia. The distribution and abundance of martens is strongly influenced by changes in habitat caused by the implementation of forestry and agricultural measures. Newer classifications based on molecular analyses of the martens are included into the magnorder Boreoeutheria, the superorder Laurasiatheria and the order Carnivora. In addition to these, in some places between the superorder of Laurasiatheria and the order of Carnivora, an unranked part of Ferae or in translation “of the beast” is also mentioned. The beech marten lives in habitats from Mongolia and the northern Himalayas to most of Europe. It is relatively rare on the islands. The northern boundary of the habitat is Denmark. The prevalence of beech marten is growing in most European countries. In the Republic of Croatia, the beech marten is a native species that inhabits the entire continental part, but it is also found on the islands. It is more numerous in karst habitats, whereas in highland and mountain areas it is found during the summer, and at the beginning of winter it usually migrates to lower areas (example of vertical migration). It often lives near human settlements, mostly next to outbuildings, backyards, under piles of stones, branches, etc. Beech marten is a typical inhabitant of open areas, but is also fond of woodland edges, rocky terrain and abandoned quarries. The beech marten is 70 to 80 cm long, and 20 to 25 cm of that length is the tail. Their height is about 25 cm, while body weight ranges from 1.5 to 2 kilograms. The body is elongated and flexible. Their skull is shaped in such a way that it can pass through small openings, searching for holes in the ground and openings in trunks. Their ears are short and the eyes are large. The claws of a beech marten are long and sharp, helping them climb and catch prey. They have a small amount of white hair on their throat, neck and chest, after which the beech marten got its name. Their diet varies and comprises food of both plant as well as animal origin; therefore, it can be said that they belong to the group of opportunistic carnivores. In accordance with the aforesaid, beech martens usually take the food that is most available, while the prey that is harder to catch is chosen in times of crisis. They hunt mostly in wooded pastures and rocky areas. Often in the absence of prey they crawl into fowl houses and chicken coops where they can do great damage. Leptospirosis is a bacterial infectious disease that affects domestic and wild animals and humans, resulting in a significant public health problem. The causes of leptospirosis are various serotypes of the bacterium classified within the species Leptospira spp. Small rodents are natural reservoirs of leptospira and can be lifelong carriers of the pathogen. Geographically, leptospirosis is widespread throughout the world, but can generally be said to be most common in areas with alkaline soils, especially in seasons when soils are warm and moist and when there is abundance of surface water. Leptospirae are thin, flexible, filamentous bacteria, 6 to 20 μm long (sometimes longer), about 0.1 μm in diameter, slightly spiral, and curled at one or both ends in a liquid medium. Leptospirae are obligate aerobes with optimal growth at temperatures from 28 to 30 ° C. Until 1989, the genus Leptospira was divided into two species, L. interrogans, which included all pathological strains, and L. biflexa, which included all saprophytic strains. Serovars that are antigenically linked are grouped within serological groups. The phenotypic classification of leptospire has been replaced by genotypic, in which all serovars are included in numerous genomic species. Based on their genetic characteristics, we now know at least 19 species of bacteria from the genus Leptospira, 6 of which are saprophytic and 13 pathogenic. In each country, depending on its climatic, geological and ecological relations, appropriate enzootic / endemic areas can be identified, and in the epizootiology / epidemiology of leptospirosis, the urinary excretion of leptospira (leptospiruria) of infected animals (especially pigs) plays a decisive role, as well as long-term survival of pathogens outside the body. When mentioning wild-type leptospirosis, rodents are considered the primary reservoir of leptospirae in rural and urban areas. In the context of a very complex research on the ecology of natural foci of leptospirosis in Croatia, emphasis has been placed on mouse-like mammals as primary reservoirs of leptospira in nature, and rodents have been determined as reservoirs of leptospira in the Sava and Drava river valleys. Canine distemper is a very contagious, often deadly, multisystem disease of susceptible carnivores. The causative agent of canine distemper is the RNA virus (CDV is an abbreviation for “canine distemper virus”) with a size of 100 to 250 nm, and it is classified in the genus Morbillivirus and the family Paramyxoviridae. This virus is widespread throughout the world and is capable of infecting numerous species of animals within the families Canidae, Procyonidae, Mustelidae, Hyaenidae, Mustelidae, Procyonidae, Ursidae, Viverridae and Felidae. Today, canine distemper is widespread throughout the world and represents a significant infectious disease of domestic and wild carnivores with a high mortality rate. According to its importance for carnivores, it is immediately behind the rabies virus. Although canine distemper has been considered a primary carnivorous disease for many years, it has recently been established that it is in fact a virus with a very wide range of potentially susceptible species. Dogs are considered the primary reservoir of disease for wildlife. Likewise, certain species of wild animals (e.g., raccoons) may be reservoirs of disease for a susceptible population of dogs. The maintenance of pathogens in nature is supported through transmission between different species of animals. At the same time, passages through organisms in which the appearance of canine distemper has not been previously recorded increase the possibility of crossing the top barrier. When it comes to martens, canine distemper is considered one of their most important infectious diseases. Thus, in Central Europe, Austria and Germany the disease has been reported in martens, ferrets, weasels and Eurasian badgers. Except for the martens, epidemiological characteristics of canine distemper in wild animals have also been studied on the example of Ethiopian wolves, lions, raccoon dogs, foxes and raccoons. MATERIAL AND METHODS: In total 64 stone martens were collected (32 males and 32 females). The processed martens were delivered from the area of northern Croatia to the Croatian Veterinary Institute (HVI) and the Faculty of Veterinary Medicine, University of Zagreb. Each marten was dissected at the dissection room of the Department for Pathological Morphology of the Croatian Veterinary Institute or at the dissection hall of the Faculty of Veterinary Medicine, University of Zagreb. During the examination of the carcass, the sex was determined, and after the opening of the thoracic and abdominal cavities, blood was sampled directly from the heart or from large blood vessels, depending on the possibilities. The latter primarily depended on the location of the hit and the application of a pellet or carbine bullets. Of all the other organs the liver and spleen were sampled for the purpose of canine distemper analysis. A part of the spleen and liver was stored in a plastic bag, properly labeled and stored in the freezer until sent for analysis. For the purpose of determining the age of the marten, the lower jaw was taken, stored in a marked plastic bag and frozen until analysis. A blood sample was screened for antibodies to Leptospira spp. using a microscopic agglutination method (MAT). The MAT method is a reference serological method for the diagnosis of leptospirosis that determines the presence of antibodies to leptospirae in the examined serum. The reaction of antigens and antibodies (IgM and / or IgG) results in the formation of insoluble agglutinate complexes, which can be performed and read in microtiter plate with wells. The test result is read under a dark field microscope in which agglutination is most visible. The method of microscopic agglutination is a qualitative and quantitative procedure because it determines the presence and quantity (titer) of antibodies at the same time. In the qualitative part of the test, it is determined whether there are antibodies for a certain serovar of leptospirae in the basic dilution of the tested serum. In case of a positive test result, a quantitative MAT is undertaken, which determines the amount of antibody - titer. Samples of brain, liver, and spleen will be screened for canine distemper virus by the polymerase chain reaction method. RNA Rneasy Midi Kit (Qiagen, Hilden, Germany) will be used to extract RNA from 51 samples of homogenized spleen tissue according to the manufacturer's instructions. Spleen and liver samples were analyzed for presence of canine distemper virus according to CASTILHO i sur. (2007.). For RNA extraction RNA Rneasy Midi Kit (Qiagen, Hilden, Njemačka) was applied in accordance with manufacturer’s instructions. Following RNA extraction, it was used as substrate for reverse transcriptase M-MuLV (Fermentas, Burlington, Kanada). A total of 20 μL of reaction mixture contains: 5 μL of extracted RNA (cca 500 ng), 5µl of extracted RNA was added to reverse transcriptase (C-DNA synthesis), containing 1x First Strand Buffer, 40U RNAseOUT. 1.3Mm of each Dntp, 50pmols of each primer. 8.5 mM DTT, 200U Superscript II Reverse Transcriptase and RNAse/DNA-se, water till 47µl of volume and was exposed to 42°C during 60 min. For PCR amplification 10µl cDNA was added to solution containing 1 x PCR Buffer, 50pmols of each primer, 0.2Mm Dntp, 2.4 Mm Mg Cl2 , 2.5 U/µl Taq DNA polymerase Recombinant i RNAse/DNAse up to volume of 102 µl and exposed to initial denaturation at 94°C during 5 mins. 35 cycles at 94°C during 45s, 48°C during 45s and 72°C during 90s followed, with final extension at 72°C during 10min. PCR products were analyzed on 1% agarose gel stained with ethidium bromide. Amplified fragments of DNA were purified with GFX PCR DNA and Gel Band Pirification Kit, and subjected to bidirectional sequencing using DYEnamic ET Dye Terminator, in accordance to manufacturers instructions. Final sequence of each sample of 447 bp was analyzed using CLUSTAL/W method and Bioedit software (HALL, 1999), with homologous sequences obtained from the GenBank. Obtained data were processed by descriptive statistical methods and regression analysis in STATISTICA 12 program, and the probability ratio in Win Episcope 2.0. The Kruskal-Wallis ANOVA test and the χ2 test were used to test the significance of the differences. Linear regression model was applied to predict relation between positive findings and increase in ambiental temperature or precipitation. RESULTS: Out of 64 analyzed animals 24 reacted positively to at least one of the Leptospira spp. Serovars, giving the prevalence of 37.5%. A total of 8 serovars were detected, presented here in decreasing order Australis (17%), Bratislava (17%), Icterohaemorrhagiae (14%), Pomona (9%), Saxkoebing (9%), Sejroe (6%), Poi (3%) and Haebdomadis (2%). Odds ratio shows 1.27 higher possibility to detect sv Australis or sv Bratislava, compared to sv. Icterohaemorrhagiae. According to the gender there was no statistically significant difference (p=0.598). Odds ratio shows 1.32 higher possibility for males to be positive, compared with females. According to age Mantel-Haenszelov test showed increasing trend, but no statistically significant difference. Statistically significant difference was found in the case sv Icterohaemorrhagiae positive samples and age (p=0.038) with statistically significant relation according to the contingency coefficient (0.341; p=0,038). No statistically significant relation was detected between sampling location and positive samples neither for subadult (χ2=1.32; p=0.251) or adult individuals (χ2=0.09; p=0.764). Linear regression model showed 2.6% higher possibility of infection if ambiental temperature becomes higher for 1 index unit, in the same time with increasing precipitation for 1 index unit probability of infection is 2.88 times higher. Analyzing the same effects on presence of sv Bratislava and sv Australis, model predicts approx. 3.8% higher possibility of infection in case of increasing ambiental temperature for 1 unit, or 1.37 times higher possibility of infection with sv. Bratislava in case of increasing precipitation. All samples were negative for CDV.DISCUSSION: Determined prevalence of 37.5% is lower than previously detected prevalence in Croatia. However, those studies were based on small sample size. Detected serovars are in general in accordance with previous findings, with exception of sv Bratislava that was added to the antigen panel much later. On the European level reported prevalence ranged from 0% to 86%. It is also necessary to mention that only one study analysed 96 samples, other were mainly up to ten animals. Serovars Bratislava and Australis are confirmed as serovars related to wildlife, while serovar Icterohaemorrhagiae may be explained by the fact that stone martens utilizes suburban areas and are frequently visiting human settlements with increasing rat population. Observed problems with studies on marten population include inadequate samples (due to exsanguination, freezing, haemolysis, etc) and small sample size due to decreasing hunting pressure on this species. Interestingly, none of the analysed samples were positive for CD virus. Further analysis are required to give better insight about role of stone martens in maintaining and spreading of leptospirosis in different habitats. Also, further research is needed to understand role of urban stone martens as source of CDV.