Borrelia miyamotoi is classified as a relapsing fever spirochete. Although B. miyamotoi is genetically and ecologically distinct from Borrelia burgdorferi sensu lato, both microorganisms are transmitted by the same Ixodes tick species. B. miyamotoi was detected in I. persulcatus ticks in 1994 in Japan. A phylogenetic analysis based on selected sequences of B. miyamotoi genome revealed genetic differences between isolates from Asia, North America, and Europe, which are clearly separated into three genotypes. Symptomatic human cases of Borrelia miyamotoi disease (BMD) were first reported in 2011 in Russia and then in North America, Europe, and Asia. The most common clinical manifestation of BMD is fever with flu-like symptoms. Several differences in rare symptoms (thrombocytopenia, monocytosis, cerebrospinal fluid pleocytosis, or symptoms related to the central nervous system) have been noted among cases caused by Asian, European, and American types of B. miyamotoi. BMD should be considered in the diagnosis of patients after tick bites, particularly with meningoencephalitis, without anti-Borrelia antibodies in the cerebrospinal fluid. This review describes the biology, ecology, and potential of B. miyamotoi as a tick-borne pathogen of public health concern, with particular emphasis on Europe.

From 2016 to 2018, ticks were collected from 272 dogs admitted to veterinary clinics in the city of Olsztyn (north-eastern Poland). Among 522 collected ticks, 423 were identified as Ixodes ricinus (413 females and 10 males) and 99 as Dermacentor reticulatus (62 females and 37 males). Non-engorged (86 individuals) and engorged (436 individuals) ticks were screened for the presence of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum DNA. Borrelia and A. phagocytophilum species detection was determined based on the sequence of the fla B and 16S RNA genes, respectively. DNA of B. burgdorferi s.l. was identified in 31.6% (165/522, 95% CI: 27.6–35.8%) of ticks (I. ricinus 151/423, 35.7%, 95% CI: 31.1–40.4%; D. reticulates 14/99, 14.1%, 95% CI: 7.9–22.6%). A. phagocytophilum was identified in 0.96% (5/522, 95% CI: 0.3–2.2%) of specimens. All positive samples were engorged I. ricinus females (5/402, 1.2%, 95% CI: 0.4–2.9%). In 85.4% (141/165, 95% CI: 79.1–90.4%) of Borrelia infected ticks, the DNA of one genospecies was revealed. The DNA of at least two different genospecies was detected in 14.5% of specimens (24/165, 95% CI: 9.5–20.8). The coexistence of B. burgdorferii s.l. and A. phagocytophilum was not detected.

This study was carried out in north-eastern Poland during two hunting seasons between 2018 and 2020. Ticks (Ixodes ricinus and Dermacentor reticulatus) were removed from wild cervids and boars and examined for the presence of Borrelia spirochetes and Rickettsiales members: Rickettsia spp. and Anaplasma phagocytophilum. The present study contributes to the knowledge of even-toed ungulates, which are an important reservoir of the above-mentioned pathogens and a potential source of infections for humans through ticks as vectors. Almost 40% of the collected ticks (191 out of 484) were infected with the following pathogens: 3.3% with Borrelia spp., 19.2% with A. phagocytophilum and 26.9% with Rickettsia spp. Only the ticks collected from cervids carried Borrelia. Typing of the species DNA confirmed the presence of B. afzelii, B. garinii, B. lusitaniae and B. miyamotoi. An analysis of Rickettsia spp. sequences using the GenBank data revealed the presence of R. helvetica, R. raoultii and R. monacensis. Monoinfections (79.1%) dominated over co-infections (20.9%). Among co-infections, the most frequent was A. phagocytophilum/Rickettsia spp. (70%), however co-infections, including B. afzelii/A. phagocytophilum, B. afzelii/Rickettsia spp., B. miyamotoi/A. phagocytophilum and B. afzelii/B. garinii/B. lusitaniae, were also noted. Significant differences were observed in the affinity of some pathogens to their vectors. Thus, Borrelia spp. and A. phagocytophilum were more frequently detected in I. ricinus (5.3% and 23.1%) than in D. reticulatus (1.2% and 15.3%). Infection frequency with Rickettsia spp. was similar (approximately 25–29%) in both tick species. The prevalence of A. phagocytophilum and Rickettsia spp. in ticks removed from cervids was 19.8% and 27.1%, and in ticks from wild boars it was 13.3% and 24.4%, respectively.

Ascaris suum is a soil-transmitted parasite causing ascariasis in pigs, largely limiting livestock production globally. Searching for new drugs affecting all stages of nematode development is necessary and widely postulated. The in vitro activity of S-methyl-(2-methoxycarbonylamino-benzoimidasole-5) thiosulfonate on A. suum developing eggs was studied. Five concentrations of the drug were used—0.625, 1.25, 2.5, 5 and 10 mM during 24, 48 and 72 h of exposure. After drug treatment, the eggs were washed and cultured in 0.05 M HCl at 27 °C for 20 days. Both the concentration and duration of the drug exposure had an inhibitory impact on the percentage of L₂ larvae developed. The best effect was obtained after 72 h of incubation in 5 mM drug solution, only 1.9 ± 3.3% of the larvae developed to the L₂ stage. Moreover, no SNP was detected at codon 167, which is correlated with benzimidazole resistance, in the tested samples. For the first time, it has been demonstrated that S-M-(2-MKA-BZ-5)TS seems to be a potential ovicidal anti-helminthic agent. It may lead to the elimination of parasites and reduce environmental contamination from roundworm eggs. The ovicidal effects of the drug should be additionally confirmed by further infection studies using experimental animals.

Neoehrlichia mikurensis is a new emerging tick-borne Gram-negative bacterium, belonging to the family Anaplasmataceae, the main vector of which in Europe is the tick Ixodes ricinus. N. mikurensis is responsible for neoehrlichiosis, occurring mostly in patients with underlying diseases. In the present study, a total of 348 I. ricinus and Dermacentor reticulatus ticks collected in north-eastern Poland were analyzed for the prevalence of N. mikurensis. A total of 140 questing ticks (124 of I. ricinus ticks and 16 D. reticulatus) collected with the flagging method and 208 ticks (105 and 103 I. ricinus and D. reticulatus, respectively) removed from dogs were selected for the study. cDNA (questing ticks) and total DNA (questing and feeding ticks) were analyzed by qPCR targeting the 16S rRNA gene of N. mikurensis. Positive samples were further analyzed by nested PCR and sequencing. The prevalence differed between ticks collected from vegetation (19.3%; 27/140) and ticks removed from dogs (6.7%; 14/208). The presence of the pathogen in questing and feeding D. reticulatus ticks was proven in Poland for the first time. In summary, our research showed that infections of ticks of both the most common tick species I. ricinus and D. reticulatus in north-eastern Poland are present and ticks collected from urban areas were more often infected than ticks from suburban and natural areas. The detection of N. mikurensis in I. ricinus and D. reticulatus ticks from north-eastern Poland indicates potential transmission risk for tick-bitten humans at this latitude.

The immune system of ticks, along with that of other invertebrates, is comparatively simpler than that of vertebrates, relying solely on innate immune responses. Direct antimicrobial defence is provided by the synthesis of antimicrobial peptides (AMPs), including defensins. The aim of this study was to investigate the differences in defensin genes expression between questing and engorged Ixodes ricinus (def1 and def2) and Dermacentor reticulatus (defDr) ticks, in the presence of selected pathogens: Borrelia spp., Rickettsia spp., Babesia spp., Anaplasma phagocytophilum, and Neoehrlichia mikurensis in the natural environment. After pathogen screening by PCR/qPCR, the expression of defensin genes in pathogen positive ticks and ticks without any of the tested pathogens, was analysed by reverse transcription qPCR. The results showed an increased expression of defensin genes in I. ricinus ticks after blood feeding and I. ricinus and D. reticulatus ticks during in cases of co-infection. In particular, the expression of defensins genes was higher in questing D. reticulatus than in questing and engorged I. ricinus ticks, when borreliae were detected. This study contributes to uncovering the expression patterns of defensin genes in the presence of several known tick pathogens, the occurrence of these pathogens and possible regulatory mechanisms of defensins in tick vector competence.