In this survey we investigated a population of small mammals in Eastern Croatia in order to determine Leptospira carriage rates and identify circulating serovars. Out of 67 trapped animals, 20 (29.9%) isolates were obtained. Identification of isolates using microscopic agglutination test, pulsed field gel electrophoresis and multi locus sequence typing revealed that 10 (50.0%) isolates belong to serogroup Pomona, serovar Mozdok, 6 (30.0%) isolates to serogroup Australis, serovar Jalna, 2 (10.0%) isolates to serogroup Sejroe, serovar Saxkoebing, and 1 (5.0%) isolate to serogroup Grippotyphosa, serovar Grippotyphosa. One isolate from serogroup Bataviae was unable to be identified to the serovar level. Amplification of a 331-bp region of the locus LA0322 using real-time polymerase chain reaction determined that 12 (60.0%) isolates belong to L. kirschneri, 6 (30.0%) isolates to L. interrogans, and 2 (10.0%) isolates to L. borgpetersenii. Leptospira carriage rate was high (29.9%), which corresponds to a high incidence of human and domestic animal leptospirosis in Eastern Croatia. Furthermore, 90.0% of the isolates belong to serogroups Pomona, Australis and Sejroe which are also the most prevalent serogroups in humans in this area. These findings suggest that small mammals might be an important source of Leptospira spp. infection in Eastern Croatia.

Feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) are among the most common infectious diseases of cats and have a global impact on the health of domestic cats. Both viruses belong to the Retroviridae family and like other members of this family they are associated with lifelong infection after integration of the proviral DNA into the host cell genome. Prevalence data are necessary to define the risk factors, and prophylactic, management, diagnostic and therapeutic measures for stray and owned sick cats. In this study 324 domestic cats were tested with commercially available assays. The tested cats were divided into two groups, stray and owned sick cats. The overall percentage of seropositives for FIV infection was 18.51% and the prevalence for FeLV infection was 14.50%. FIV prevalence ranged from 13.13% in stray cats up to 20.88% within the sick owned cat group. The prevalence for FeLV infection was 6.06% in stray cats and 18.22% among sick owned cats. Regarding FIV infection, our study confirmed a significantly higher percentage of seropositives for male cats, as well as for sexually intact ones within the sick owned group. Males were significantly more likely to have positive results for both retroviral infections. The study confirmed the high rate of retroviral infections in cats from the Zagreb urban area. Males, sexually intact ones, and territorial aggression are predisposing factors for FIV infection, but not for FeLV. Preventive measures should include identification and segregation of infected cats, castration of outdoor male cats, and vaccination.

The feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) may cause persistent, lifelong and lethal infections in domestic and wild felids worldwide. FIV has been confirmed in most Felidae species, while FeLV infection is rare among non-domestic cats. The view that retroviruses are pathogenic in domestic cats but not in other free-ranging felid species was disproved by recent findings of retroviral pathology in several wild felids. The epidemiology of retroviral infections in felids in Croatia was only investigated in urban domestic cats, while there are no data for wild cat species. As the reintroduced Dinaric lynx (Lynx lynx) population suffers from low genetic diversity, which reduces their ability to adapt to new viral outbreaks, the health status of this lynx population is of particular concern. Two different commercial immunochromatographic assays were used for qualitative detection of FIV antibodies and FeLV antigens, while PCR was used for amplification of proviral gag and env genes in Eurasian lynx blood samples. All the 17 Eurasian lynx samples collected between 2001 and 2019 tested negative in both immunochromatographic and molecular tests. Even though our sample size was rather small, considering the fact that the population size of lynx in Croatia is estimated at 40 - 60 animals, our results can be considered representative for the population’s health status. Also, data about retroviral prevalence in Eurasian lynxes are scarce, so any new findings are very valuable.

Contagious equine metritis (CeM) is a highly contagious venereal disease caused by the bacterium Taylorella equigenitalis. In Croatia, horses are almost never tested for this disease unless it is specifically requested. to date, no positive bacteriology results for T. equigenitalis have ever been obtained in Croatia. During 2014 and 2015, 12 animals were screened for T. equigenitalis using both bacteriology and a polymerase chain reaction (PCr) test. No positive cultures were obtained, however, samples from three animals tested positive on PCr. Sequencing of the PCr products revealed that one animal was positive for T. equigenitalis and two animals for T. asinigenitalis. These results represent the first evidence of T. equigenitalis and T. asinigenitalis infections in horses in Croatia. the high prevalence of T. equigenitalis and T. asinigenitalis positive horses (n = 3) in the population tested (n = 12) strongly suggests that the overall prevalence of horses positive for Taylorella spp. in Croatia is high, and that the equine population, especially those animals used for breeding, should be regularly tested for this bacterium. In addition, these results show the low sensitivity of using culture alone and that additional molecular methods should be utilised to identify positive cases of Taylorella spp.

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.