There is now considerable evidence that in Europe, babesiosis is an emerging infectious disease, with some of the causative species spreading as a consequence of the increasing range of their tick vector hosts. In this review, we summarize both the historic records and recent findings on the occurrence and incidence of babesiosis in 20 European countries located in southeastern Europe (Bosnia and Herzegovina, Croatia, and Serbia), central Europe (Austria, the Czech Republic, Germany, Hungary, Luxembourg, Poland, Slovakia, Slovenia, and Switzerland), and northern and northeastern Europe (Lithuania, Latvia, Estonia, Iceland, Denmark, Finland, Sweden, and Norway), identified in humans and selected species of domesticated animals (cats, dogs, horses, and cattle). Recorded cases of human babesiosis are still rare, but their number is expected to rise in the coming years. This is because of the widespread and longer seasonal activity of Ixodes ricinus as a result of climate change and because of the more extensive use of better molecular diagnostic methods. Bovine babesiosis has a re-emerging potential because of the likely loss of herd immunity, while canine babesiosis is rapidly expanding in central and northeastern Europe, its occurrence correlating with the rapid, successful expansion of the ornate dog tick (Dermacentor reticulatus) populations in Europe. Taken together, our analysis of the available reports shows clear evidence of an increasing annual incidence of babesiosis across Europe in both humans and animals that is changing in line with similar increases in the incidence of other tick-borne diseases. This situation is of major concern, and we recommend more extensive and frequent, standardized monitoring using a “One Health” approach.

Bartonella are vector-borne parasitic bacteria that cause zoonotic infections in humans. One of the most common infections is cat-scratch disease caused by Bartonella henselae and Bartonella clarridgeiae. Cats are the major reservoir for these two species of bacteria, while cat fleas are vectors for the transmission of infection agents among cats. The aim of the present study was to investigate the presence of Bartonella infections in stray and pet cats and in cat fleas in Lithuania. Blood samples were taken from 163 cats presented in pet clinics and animal shelters. A total of 102 fleas representing two species, Ctenocephalides felis and Ctenocephalides canis, were collected from 12 owned cats that live both outdoors and indoors. Bartonella DNA in samples was detected using a nested PCR targeting the 16S–23S rRNA intergenic spacer (ITS) region. Bartonella DNA was detected in 4.9% (8/163) of the cats and 29.4% (30/102) of the fleas. Sequence analysis of the ITS region showed that the cats and fleas were infected with B. henselae, B. clarridgeiae and Bartonella sp., closely related to B. schoenbuchensis. This study is the first report on the prevalence and molecular characterization of Bartonella spp. in cats and cat fleas in Lithuania.

Summary: Over the past decade, increasing numbers of autochthonous cases of heartworm infection have been reported in the countries of Eastern Europe where previously only imported cases were described. In this report we have described the first clinical case of Dirofilaria immitis infection in an imported dog in Lithuania. In 2018, a 5-year-old male Spanish greyhound (Spanish galgo) was imported to Lithuania from southern Spain and referred to a small animal veterinary clinic in Vilnius for wellness screening. Circulating microfilariae and female antigens of D. immitis were detected using the Knott’s test and SNAP 4Dx Plus Test (IDEXX Laboratories, Portland, USA). The diagnosis was confirmed using molecular analysis. Treatment according to the guidelines recommended by the American Heartworm Society was applied. This is the first confirmed report of canine heartworm infection in an imported dog in Lithuania. Heartworm - infected dogs transported to North-Eastern Europe from endemic areas could act as microfilarial reservoirs for the local mosquito population, which could increase the risk of spreading the disease.

Babesia microti (Aconoidasida: Piroplasmida) (Franca, 1910) is an emerging tick-borne parasite with rodents serving as the considered reservoir host. However, the distribution of B. microti in Europe is insufficiently characterized. Based on the sample of 1180 rodents from 19 study sites in Lithuania, the objectives of this study were: (1) to investigate the presence of Babesia parasites in eight species of rodents, (2) to determine the prevalence of Babesia parasites in rodents from different habitats, and (3) to characterize the detected Babesia strains using partial sequencing of the 18S rRNR gene. Babesia DNA was detected in 2.8% rodents. The highest prevalence of Babesia was found in Microtus oeconomus (14.5%) and Microtus agrestis (7.1%) followed by Clethrionomys glareolus (2.3%), Apodemus flavicollis (2.2%) and Micromys minutus (1.3%). In M.minutus, Babesia was identified for the first time. The prevalence of Babesia-infected rodents was higher in the meadow (5.67%) than in the ecotone (1.69%) and forest (0.31%) habitats. The sequence analysis of the partial 18S rRNA gene reveals that Babesia isolates derived from rodents were 99–100% identical to human pathogenic B. microti ‘Jena/Germany’ strain.

Bartonella bacteria infect the erythrocytes and endothelial cells of mammalians. The spread of the Bartonella infection occurs mainly via bloodsucking arthropod vectors. Studies on Bartonella infection in European bison, the largest wild ruminant in Europe, are lacking. They are needed to clarify their role in the maintenance and transmission of Bartonella spp. The aim of this study was to investigate the presence of the Bartonella pathogen in European bison and their ticks in Lithuania. A total of 38 spleen samples from bison and 258 ticks belonging to the Ixodes ricinus and Dermacentor reticulatus species were examined. The bison and tick samples were subjected to ssrA, 16S–23S rRNA ITS, gltA, and rpoB partial gene fragment amplification using various variants of PCR. Bartonella DNA was detected in 7.9% of the tissue samples of European bison. All tick samples were negative for Bartonella spp. The phylogenetic analysis of 16S–23S rRNA ITS, gltA, and rpoB partial gene fragment revealed that European bison were infected by B. bovis (2.6%) and B. schoenbuchensis (5.3%). This is the first report addressing the occurrence of B. bovis and B. schoenbuchensis in European bison in Europe.