Toxoplasma gondii infection in ticks infesting migratory birds: the blackbird (Turdus merula) and the song thrush (Turdus philomelos).

Toxoplasmosis, caused by the protozoan Toxoplasma gondii, is the zoonosis widespread all over the world. Birds constitute an important group of T. gondii intermediate hosts often attacked by definitive hosts, e.g. domestic cats. Due to confirmation of an additional way of T. gondii transmission via tick bite, the aim of our study was to state and evaluate the infection prevalence of ticks feeding on blackbirds (Turdus merula) and song thrushes (Turdus philomelos). The real-time PCR amplification of the B1 gene fragment was used for detection of T. gondii infection in 157 Ixodes ricinus ticks removed from captured birds. The results showed the thrushes as hosts intensively attacked by ticks (prevalence 88.5% and 70% for blackbirds and song thrushes, respectively), and T. gondii infected individuals were detected. Among all ticks infected, 7 (5.8%; n = 120) were collected from blackbirds, and 2 (5.4%; n = 37) from song thrushes. The thrushes small body sizes and their tendency to urban ecosystems colonization, suggest that they relatively often become a pray of domestic cats, and combined with our findings, are potentially involved in maintenance the T. gondii population, especially in anthropogenic habitats, where the presence of toxoplasmosis is likely to constitute a serious danger to public health.

Rickettsiales Occurrence and Co-occurrence in Ixodes ricinus Ticks in Natural and Urban Areas.

Bacteria of Rickettsiaceae and Anaplasmataceae families include disease agents spread by Ixodes ricinus ticks, the most common tick vector in Europe. The aim of the study was to compare the prevalence and co-infection prevalence of particular tick-transmitted Rickettsiales members: Rickettsia spp. (further referred as Rs), Anaplasma phagocytophilum (Ap), and "Candidatus Neoehrlichia mikurensis" (CNM) in I. ricinus ticks in two types of areas, different in terms of human impact: natural and urban. Using additional data, we aimed at investigating co-occurrence of these Rickettsiales with Borreliella spp. A total of 4189 tick specimens, 2363 from the urban area (Warsaw park and forests) and 1826 from the natural area (forests and park in the vicinity of National Parks), were tested for the presence of Rickettsiales DNA by PCRs. The prevalence of selected Rickettsiales was twice higher in urban than natural areas (13.2% vs. 6.9%, respectively). In total ticks, the prevalence of Rs, Ap, and CNM was 6.5%, 5.3%, and 3.6% in urban areas vs. 4.4%, 1.1%, and 2.1% in natural areas, respectively. Co-infections of Rickettsiales were also more prevalent in urban areas (2.6% vs. 0.3%, respectively). The most common Rs was R. helvetica; also R. monacensis and novel "Candidatus Rickettsia mendelii" were detected. Positive association between Ap and CNM infections was discovered. Rickettsiales bacteria occurrence was not associated with Borreliella occurrence, but co-infections with these two groups were more common in ticks in urban areas. In conclusion, three groups of Rickettsiales constituted the important part of the tick pathogen community in Poland, especially in the urbanized central Poland (Mazovia). In the Warsaw agglomeration, there is a greater risk of encountering the I. ricinus tick infected with Rickettsiales and co-infected with Lyme spirochaetes, in comparison to natural areas. This finding raises the question whether cities might in fact be the hot spots for TBDs.

New findings of Setaria tundra and Setaria cervi in the red deer (Cervus elaphus) in Poland.

Our study aimed at examining the phylogenetic position of the newly-found Setaria nematodes obtained from the red deer (Cervus elaphus) based on sequences of the mitochondrial cytochrome c oxidase subunit 1 (COX-1). Alignment and phylogenetic analyses, as well as SEM microscopic analysis, revealed the presence of two Setaria species: S. cervi and S. tundra. Setaria tundra was noted in only one individual, a calf of the red deer, while S. cervi was observed in three stages, two hinds and one calf of the red deer. According to our knowledge, it is the first case of S. cervi in the red deer in Poland confirmed in molecular studies and also the first case of S. tundra infection in the red deer.

Molecular identification of tick-borne pathogens in asymptomatic individuals with human immunodeficiency virus type 1 (HIV-1) infection: a retrospective study.

BACKGROUND: The studies on the occurrence and diversity of tick-borne infections in HIV-infected individuals have been few, and the subject has been relatively neglected when compared with other common infections associated with HIV. In HIV-positive patients in whom a serological diagnostics is complicated due to reduced positive predictive value, a method where the microorganism is detected directly is of great value. Therefore, we performed a molecular study to ascertain the prevalence and incidence of tick-borne infections in HIV-infected persons in Poland, an endemic area for Ixodes ricinus ticks. METHODS: Genomic DNA was isolated from whole blood of tested patients. Detection of tick-borne pathogens was performed by amplification and sequencing of different loci. Molecular and phylogenetic analyses of obtained nucleotide sequences were performed. Serum samples were analyzed for antibodies against tick-borne pathogens by using commercial tests in all patients. RESULTS: Among 148 studied blood samples from HIV-infected patients, two cases (1.4%) of infection with tick-borne pathogen were reported. No symptoms of tick-borne infection were observed in these cases. In one case a patient was infected with Anaplasma phagocytophilum - the agent of human granulocytic anaplasmosis (HGA) and in the other with Borrelia garinii. CONCLUSIONS: Our study revealed the first case of HIV positive patient infected with A. phagocytophilum. Asymptomatic tick-borne infection can occur in HIV-positive patients. The detailed history of tick bites, especially in endemic tick areas, should be considered as part of anamnesis in routine clinical care of HIV-positive patients.

Prevalence of Cryptosporidium, Blastocystis, and other opportunistic infections in patients with primary and acquired immunodeficiency.

Intestinal opportunistic infections are often caused by unicellular parasites. Individuals with decreased immunity are particularly susceptible to infection by said microorganisms, and when they are infected, diarrhea can be the main clinical manifestation. However, intestinal parasites have rarely been taken into account in intestinal disorders. In our study, an investigation was conducted to determine the prevalence of intestinal micro-pathogens, such as Cryptosporidium, Giardia, Blastocystis, and microsporidia, in hospitalized patients with different immunological statuses. The study at hand indicates that protozoan parasitic infections are rare among immunodeficient patients in Poland. The overall prevalence of micro-pathogens among participants was 4.6%; it was three times higher in adults (12.5%) than in children (2.3%). Cryptosporidium and Cyclospora species (Apicomplexa) were diagnosed as the main cause of heavy diarrhea. Accordingly, adult patients were positive mainly for Blastocystis and microsporidia, while children were more often infected with the Cryptosporidium species.

Selected aspects of helminth infections Schistosoma sp., Ascaris lumbricoides, Strongyloides stercoralis in individuals diagnosed with human immunodeficiency virus (HIV) infection

Co-infections of HIV and other pathogens constitute an important clinical and epidemiological problem. Many studies have played attention to opportunistic co-infections due to the fact that they are used as an indicator for development of AIDS and are present on the all continents. However, in HIV-infected patients helminth infections, which are not aetiologic agents of opportunistic infections, are becoming more and more important. Prevalence of helminth infection depends on parasite species, environmental and socio-economic factors, therefore the results of published research mainly refer to populations of patients in developing countries and endemic regions. In many cases, pathogenetic mechanisms of these co-infections are not fully recognized, and the obtained results are ambiguous. Thus we performed literature review concerning the course and implications of co-infections with three selected helminth species, of different tissue/organ tropism (Ascaris lumbricoides, Strongyloides stercoralis, Schistosoma sp.), in patients with HIV infection.

The prevalence of Dirofilaria repens in cats, healthy dogs and dogs with concurrent babesiosis in an expansion zone in central Europe.

BACKGROUND: Dirofilaria repens is a mosquito-transmitted, filarial nematode parasitizing dogs, cats and other carnivores. Recently, this parasite has spread in central Europe, including Poland. The aim of the present study was to estimate the prevalence of D. repens in cats and dogs in different regions of the country and to investigate the occurrence and consequences of co-infection with another fast-spreading vector-borne parasite, Babesia canis. RESULTS: In the period 2013-2015, 147 blood samples from cats from central Poland and 257 blood samples from dogs from central, northern, southern and western Poland were collected. Prevalence of D. repens was determined by amplification and sequencing of the 12S rDNA gene fragment. Among dogs, 94 samples originated from clinically healthy dogs from central Poland (Masovia) and 58 samples originated from dogs that were infected with B. canis. Prevalence of D. repens was compared between these two groups of dogs. For the first time D. repens was identified in a cat from central Europe (0.7 % [95 % CL: 0-4.1 %]). The DNA of the filarial endosymbiotic bacterium Wolbachia was detected in two cats (1.4 % [95 % CL: 0-5.5 %]). In dogs, the parasite was detected only in samples from central Poland (Masovia) (local prevalence = 38 % [95 % CL: 25.9-51.8 %]). Prevalence of D. repens was significantly higher in dogs with babesiosis (90 % [95 % CL: 81.6-94.5 %]). Co-infections of D. repens and B. canis were confirmed by sequencing in 30 dogs with babesiosis, but no co-infections were identified in healthy dogs from Masovia. Statistical analyses of blood parameters revealed that dogs with co-infections suffered more severe anemia and thrombocytopenia, but presented milder changes in biochemical parameters (i.e. less elevated concentration of alkaline phosphatase [ALP] and serum urea) suggesting lower risk of hepatic or renal failure in comparison to dogs infected only with B. canis. CONCLUSIONS: These findings are important due to the spread of dirofilariosis and babesiosis in central Europe, as microfilaraemic dogs seem to be more prone to babesiosis. The possible protective effect of the nematode infection against hepatic or renal failure in canine babesiosis and its mechanisms require further investigations.

Long-term study of the prevalence of Borrelia burgdorferi s.l. infection in ticks (Ixodes ricinus) feeding on blackbirds (Turdus merula) in NE Poland.

Seeking evidence to confirm that blackbirds (Turdus merula) may be involved in environmental maintenance of Borrelia burgdorferi s.l. (the causative agent of Lyme borreliosis), we conducted a long-term study over three separate 2-year periods, together embracing a span of almost 20 years, all in the same area in northeastern Poland. We examined a total of 78 blackbirds and collected 623 Ixodes ricinus ticks feeding on them. The tick infestation prevalence was found to be very high (89.7 %). Among all ticks collected, 9.8 % individuals were infected with B. burgdorferi s.l. spirochetes. We found statistically significant growth in the prevalence of infected ticks as well as an increasing proportion of blackbirds hosting them in subsequent years of study. Ticks feeding on blackbirds were infected mainly with B. garinii (45.7 %), a genospecies commonly encountered in birds, and with B. afzelii (28.6 %), until recently considered rodent-associated. We also identified B. turdi (22.9 %), frequently found in recent years in ticks feeding on birds, and B. spielmanii (2.8 %), which had previously not been found in infected ticks feeding on blackbirds. We also found that ticks infected with genospecies associated with avian reservoir groups (B. garinii and B. turdi) were not randomly distributed on blackbirds, but instead focused on certain bird specimens. We therefore conjecture that this is a result of ticks becoming infected either from the host blackbird itself, or from other infected ticks feeding on the same host blackbird. We did not find any similar dependency for the rodent specialist B. afzelii.

Dominance of Dermacentor reticulatus over Ixodes ricinus (Ixodidae) on livestock, companion animals and wild ruminants in eastern and central Poland.

The most common tick species parasitizing animals in Poland are Ixodes ricinus and Dermacentor reticulatus. These tick species differ in their distribution, habitats, seasonal activity and host specificity. Ixodes ricinus is the most prevalent and widely distributed, whereas the range of D. reticulatus is limited to eastern and central parts of the country with several new foci in the middle-west and the west. However, as in many central European countries, the range of D. reticulatus is expanding, and some authors have correlated this expansion with an increasing number of available hosts. The aim of the present study was to determine the tick fauna on domestic and livestock animals in two areas endemic for I. ricinus and D. reticulatus and to compare the risk of infestation with different tick species in open and forest areas. Over a 14 month period, 732 ticks were collected from five host species including domestic animals (dogs and cats), livestock (cows and horses) and wildlife (European bison) in two areas, central and NE Poland, endemic for D. reticulatus. Three tick species were recorded: D. reticulatus (623 individuals; 85.1% of all collected ticks), I. ricinus (106 individuals; 14.5%) and three females of Ixodes hexagonus (0.4%) from a dog. Dermacentor reticulatus was the dominant tick species found on four host species and constituted 86, 81, 97 and 100% of all ticks from dogs, horses, cows and bison, respectively, and was collected from animals throughout the year, including during the winter. The common tick, I. ricinus, was the dominant tick collected from cats (94%). Fully-engorged, ready-for-reproduction females of D. reticulatus were collected from all host species. In May 2012, questing ticks were collected by dragging in forest or open habitats. The density of adult marsh ticks in open areas was around 2 ticks/100 m(2) in the majority of locations, with a maximum of 9.5 ticks/100 m(2). The density of adult I. ricinus was much lower in its typical habitat (forests: range 0.8-2.2 ticks/100 m(2)) between three and seven times lower than the density of D. reticulatus in its typical habitat. In regions endemic for marsh ticks, this tick species constitutes the main risk of tick infestation for livestock and dogs throughout the year. Livestock and companion animals are competent hosts for D. reticulatus, enabling the completion of the tick's life cycle. Anti-tick treatment should be adjusted to marsh tick seasonal activity and drug sensitivity.

Asymptomatic "Candidatus Neoehrlichia mikurensis" infections in immunocompetent humans.

In Europe, human infections with "Candidatus Neoehrlichia mikurensis" have mainly been restricted to immunocompromised patients. We report here the first cases of asymptomatic "Ca. Neoehrlichia mikurensis" infection in immunocompetent humans (5/316 [1.6%] were infected). Due to the potential threats of infections with "Ca. Neoehrlichia mikurensis" in healthy persons to the safety of the blood supply, further study of this phenomenon is required.

Long-term spatiotemporal stability and dynamic changes in the haemoparasite community of bank voles (Myodes glareolus) in NE Poland.

Long-term field studies on parasite communities are rare but provide a powerful insight into the ecological and evolutionary processes shaping host-parasite interactions. The aim of our study was to identify the principal factors regulating long-term trends in the haemoparasite communities of bank voles, and to this end, we sampled three semi-isolated populations of bank voles (n = 880) in 1999, 2002, 2006 and 2010 in the Mazury lake district region of NE Poland. Overall, 90.8 % of the bank voles harboured at least one of the species of haemoparasites studied. Whilst overall prevalence (all species combined) did not vary significantly between the surveys, different temporal changes were detected among voles in each of the three sites. In voles from Urwitalt, prevalence increased consistently with successive surveys, whereas in Talty, the peak years were 2002 and 2006, and in Pilchy, prevalence oscillated without a clear pattern. Across the study, bank voles harboured a mean of 1.75 ± 0.034 haemoparasite species, and species richness remained stable with no significant between-year fluctuations or trends. However, each of the five constituent species/genera showed a different pattern of spatio-temporal changes. The overall prevalence of Babesia microti was 4.9 %, but this varied significantly between years peaking in 2006 and declining again by 2010. For Bartonella spp., overall prevalence was 38.7 %, and this varied with year of study, but the temporal pattern of changes differed among the three sites. The overall prevalence of Haemobartonella (Mycoplasma) was 68.3 % with an increase in prevalence with year of study in all three sites. Hepatozoon erhardovae had an overall prevalence of 46.8 % but showed a marked reduction with each successive year of the study, and this was consistent in all three sites. The overall prevalence of Trypanosoma evotomys was 15.4 % varying significantly between sites, but showing temporal stability. While overall prevalence of all haemoparasites combined and species richness remained stable over the period of study, among the five haemoparasites, the pattern of spatiotemporal changes in prevalence and abundance of infections differed depending on parasite species. For some genera, host age was shown to play an important role, but a significant effect of host sex was found only for Haemobartonella spp.

A seven-legged tick - anomalous Ixodes ricinus female (Acari: Ixodidae) from Poland.

Morphological anomalies are considered a rare phenomenon among natural tick populations. New cases of abnormalities in ticks are being described, such as body assymetries, nanism, gynandromorphism and limb malformations. The tick removed from a cat was morphologically identified to species and developmental stage. The time of feeding on the host was determined. The specimen was tested using PCR and Real-Time PCR methods for the presence of the common tick-borne pathogens: Anaplasma phagocytophilum, Babesia spp, Borrelia spp., Neoehrlichia mikurensis, Rickettsia spp. For visualisation of the anomalous structures, scanning electron microscopy (SEM) was performed. The tick was identified as a slightly engorged adult female of I. ricinus exhibiting ectromely of leg I on the left side of the idiosoma. The specimen was tested positive for two medically important pathogens: A. phagocytophilum and N. mikurensis. The case report describes a rare case of a morphological anomaly in an I. ricinus tick from Poland.

Seroprevalence of Toxoplasma gondii and Borrelia burgdorferi infections in patients with multiple sclerosis in Poland.

Multiple sclerosis (MS) is a chronic, demyelinating disease of the central nervous system that affects mainly young people. It is believed that the autoimmune process observed in the pathogenesis of MS is influenced by a complex interaction between genetic and environmental factors, including infectious agents. The results of this study suggest the protective role of Toxoplasma gondii infections in MS. Interestingly, high Toxoplasma IgM seropositivity in MS patients receiving immunomodulatory drugs (IMDs) was identified. On the other hand, Borrelia infections seem to be positively associated with MS. Although the interpretation of our results is limited by the retrospective nature of the studies, the results strongly indicate that further experimental and clinical studies are needed to explain the role of infectious agents in the development and pathophysiological mechanisms of MS.

Tick-borne infections in wolves from an expanding population in Eastern Europe.

In Central and Eastern Europe, wolf populations have been increasing over the last two decades, recolonizing areas from which the species had been previously exterminated. As wolves are still recovering after years of persecution by humans, recognizing pathogens infecting this species, including tick-borne infections, is crucial for its conservation. On the other hand the high mobility of wolves and their frequent contacts with humans, dogs, and other domestic species make them a potentially important zoonotic reservoir. In this paper, we used molecular methods to determine the prevalence of tick-borne pathogens in the following genera: Anaplasma, Babesia, Bartonella, Borrelia, and Rickettsia in 50 free-ranging wolves from Poland. We detected Babesia canis in the blood of nine individuals (prevalence 9/50=18 %). The obtained sequence showed the highest similarity to B. canis isolated from dogs and ticks, and all infected individuals originated from regions endemic to the ornate tick, Dermacentor reticulatus. Anaplasma phagocytophilum was found in tissue from one individual (1/50=2 %), and the sequence was assigned to the zoonotic ecotype I.

Cytokine gene polymorphism and parasite susceptibility in free-living rodents: Importance of non-coding variants.

Associations between genetic variants and susceptibility to infections have long been studied in free-living hosts so as to infer the contemporary evolutionary forces that shape the genetic polymorphisms of immunity genes. Despite extensive studies of proteins interacting with pathogen-derived ligands, such as MHC (major histocompatilbility complex) or TLR (Toll-like receptors), little is known about the efferent arm of the immune system. Cytokines are signalling molecules that trigger and modulate the immune response, acting as a crucial link between innate and adaptive immunity. In the present study we investigated how genetic variation in cytokines in bank voles Myodes glareolus affects their susceptibility to infection by parasites (nematodes: Aspiculuris tianjensis, Heligmosomum mixtum, Heligmosomoides glareoli) and microparasites (Cryptosporidium sp, Babesia microti, Bartonella sp.). We focused on three cytokines: tumour necrosis factor (TNF), lymphotoxin alpha (LTα), and interferon beta (IFNß1). Overall, we identified four single nucleotide polymorphisms (SNPs) associated with susceptibility to nematodes: two located in LTα and two in IFNß1. One of those variants was synonymous, another located in an intron. Each SNP associated with parasite load was located in or next to a codon under selection, three codons displayed signatures of positive selection, and one of purifying selection. Our results indicate that cytokines are prone to parasite-driven selection and that non-coding variants, although commonly disregarded in studies of the genetic background of host-parasite co-evolution, may play a role in susceptibility to infections in wild systems.

Rickettsia species in Dermacentor reticulatus ticks feeding on human skin and clinical manifestations of tick-borne infections after tick bite.

Dermacentor reticulatus ticks are sporadically removed from human skin and therefore the medical consequences of their feeding are neglected compared to Ixodes ricinus. We investigated the prevalence of pathogens in D. reticulatus removed from human skin and possible clinical manifestations suggestive of tick-borne diseases after a tick bite. A total of 2153 ticks were studied and of these only 34 were D. reticulatus. The mean prevalence of Rickettsia in D. reticulatus was 50.0% and R. raoultii was identified in 82.4% of infected D. reticulatus ticks. We confirmed the first case of R. aeschlimannii infection in D. reticulatus ticks. Among participants bitten by D. reticulatus, 13.3% reported reddening around the tick bite site and flu-like symptoms, including lymphadenopathy and 3.3% reported eschar on the tick site bite. All of the participants with flu-like symptoms after tick removal were bitten by ticks infected with R. raoultii. The results of this study indicate that even though D. reticulatus ticks bite humans sporadically, pathogenic Rickettsia have a remarkably high prevalence in this tick species. We can expect that the incidence of tick-borne lymphadenopathy might increase with the reported expansion of the D. reticulatus into new areas and its growing abundance in Central Europe.

Enteroviral central nervous system infections in patients with Lyme neuroborreliosis.

Patients with Lyme neuroborreliosis (LNB) are rarely tested for the presence of neurovirulent viruses other than tick-borne encephalitis virus (TBEV); however, such coinfections could be of clinical importance. The aim of the study was to search for the presence of neurotropic viruses in a LNB patients. Fourteen patients admitted with signs and symptoms of neuroinfection who were eventually diagnosed to have LNB (according to the guidelines of the European Federation of Neurological Societies) were subjects of the study. Sera and cerebrospinal fluid (CSF) collected at the time of initial presentation were tested for viral pathogens most common in our geographical area: human enteroviruses (EV), herpes simplex virus type 1 and 2, varicella-zoster virus, Epstein-Barr virus, cytomegalovirus, human herpesvirus type 6, human adenoviruses, and TBEV using PCR/RT-PCR and serological assays. RNA and DNA-based metagenomic next-generation sequencing (mNGS) was used to detect other viral pathogens. EV was detected in CSF from two (14 %) LNB patients and viral loads were similar (220 and 270 copies/ml). The mMGS analysis were performed on CSFs from 10 patients and generated a total 213,750,885 NGS reads, 0.05 % of which were viral. However, none of potential pathogens fulfilled the criteria for positive viral detection by mNGS. Using a number of PCR/RT-PCR assays and mNGS we identified EV infection in two out of 14 LNB patients. The possible co-occurrence of enterovirus and Lyme neuroborreliosis infections may warrant further research.

Seronegative Infection with Toxoplasma gondii in Asymptomatic Human Immunodeficiency Virus Type 1 (HIV-1)-Infected Patients and in Blood Donors.

BACKGROUND: Toxoplasmosis is a common opportunistic infection in AIDS patients. The routine diagnostics is based on serologic testing and IgG avidity index, but it may have limited utility in immunodeficient patients; thus, it is recommendable to detect T. gondii DNA in subjects with advanced HIV disease. The results of the studies published so far focused on patients with clinical symptoms of toxoplasmosis. Our study encompassed a group of HIV-infected subjects on cART therapy, without immunological disturbances and clinical symptoms of T. gondii infection. METHODS: The study was retrospective, and samples were collected between 2013 and 2016. We evaluate the prevalence of serological (IgM, IgG, and avidity IgG) and molecular (DNA) T. gondii infection markers in asymptomatic HIV-infected patients and the control group using serologic (ELISA) and quantitative (real-time PCR) molecular testing. RESULTS: Of 152 HIV-infected in routine follow-up tested for T. gondii IgM and IgG, 6 (3.9%) and 50 (32.9%) were positive, respectively. Of 168 serum samples from blood donors, 1 (0.6%) and 49 (29.2%) were IgM+ and IgG+ positive, respectively. IgM seroprevalence in HIV-infected patients was significantly higher than in blood donors. T. gondii DNA (genotype II) was identified in 47 (30.9%) HIV-infected patients, with 13 (8.6%) IgM-IgG- samples. In blood donors, T. gondii DNA was present in 15 (8.9%) IgM-IgG-. CONCLUSIONS: In both groups, T. gondii DNA was detectable in seronegative subjects, implying the need to supplement the routine serological testing via the molecular method. It can help the accurate monitoring of the reactivation of infection in asymptomatic HIV-infected persons, and the quick introduction of specific therapy, in blood donors, would be of high importance for safe blood donations.

Babesia spp. infections transmitted through blood transfusion.

Babesiosis in humans is caused by infection with various species of Babesia (Apicomplexa, Piroplasmida), mainly transmitted by an arthropod vector--Ixodes spp. ticks. This review will focus on blood transfusion as another mode of Babesia transmission, especially in endemic areas, as well as the impact of human babesiosis on transfusion medicine.

Long-term study of Borrelia and Babesia prevalence and co-infection in Ixodes ricinus and Dermacentor recticulatus ticks removed from humans in Poland, 2016-2019.

BACKGROUND: Lyme borreliosis (LB) is the most common vector-borne disease in Europe. Monitoring changes in the prevalence of different Borrelia species in ticks may be an important indicator of risk assessment and of differences in pathogenicity in humans. The objective of our study was to assess the prevalence, co-infection and distribution of Borrelia and Babesia species in ticks removed from humans in a large sample collected during a study period of 4 years. METHODS: The ticks were collected throughout Poland from March to November over 4-year period from 2016 to 2019. All ticks (n = 1953) were morphologically identified in terms of species and developmental stage. Molecular screening for Borrelia and Babesia by amplification of the flagellin gene (flaB) or 18S rRNA marker was performed. Pathogen identity was confirmed by Sanger sequencing or PCR-restriction fragment length polymorphism analysis. RESULTS: The ticks removed from humans in Poland during this study belonged to two species: Ixodes ricinus (97%) and Dermacentor reticulatus (3%). High Borrelia prevalence (25.3%), including B. miyamotoi (8.4%), was confirmed in Ixodes ricinus ticks removed from humans, as was the change in frequency of occurrence of Borrelia species during the 4-year study. Despite Babesia prevalence being relatively low (1.3%), the majority of tested isolates are considered to be pathogenic to humans. Babesia infection was observed more frequently among Borrelia-positive ticks (2.7%) than among ticks uninfected with Borrelia (0.8%). The most frequent dual co-infections were between Borrelia afzelii and Babesia microti. The presence of Borrelia was also confirmed in D. reticulatus (12.7%); however the role of these ticks in spirochete transmission to susceptible hosts is still unclear. CONCLUSIONS: Although the overall risk of developing LB after a tick bite is low in Europe, knowledge of the prevalence and distribution of Borrelia and Babesia species in ticks might be an important indicator of the risk of both these tick-borne diseases.