Detection of pathogens in ixodid ticks collected from animals and vegetation in five regions of Ukraine

Frequency of Anaplasma phagocytophilum, Borrelia spp., and coinfections in Ixodes ricinus ticks collected from dogs and cats in Germany

BACKGROUND

Changing geographical and seasonal activity patterns of ticks may increase the risk of tick infestation and tick-borne pathogen (TBP) transmission for both humans and animals.

METHODS

To estimate TBP exposure of dogs and cats, 3000 female I. ricinus from these hosts were investigated for Anaplasma phagocytophilum and Borrelia species.

RESULTS

qPCR inhibition, which was observed for ticks of all engorgement stages but not questing ticks, was eliminated at a template volume of 2 µl. In ticks from dogs, A. phagocytophilum and Borrelia spp. prevalence amounted to 19.0% (285/1500) and 28.5% (427/1500), respectively, while ticks from cats showed significantly higher values of 30.9% (464/1500) and 55.1% (827/1500). Accordingly, the coinfection rate with both A. phagocytophilum and Borrelia spp. was significantly higher in ticks from cats (17.5%, 262/1500) than dogs (6.9%, 104/1500). Borrelia prevalence significantly decreased with increasing engorgement duration in ticks from both host species, whereas A. phagocytophilum prevalence decreased only in ticks from dogs. While A. phagocytophilum copy numbers in positive ticks did not change significantly over the time of engorgement, those of Borrelia decreased initially in dog ticks. In ticks from cats, copy numbers of neither A. phagocytophilum nor Borrelia spp. were affected by engorgement. Borrelia species differentiation was successful in 29.1% (365/1254) of qPCR-positive ticks. The most frequently detected species in ticks from dogs were B. afzelii (39.3% of successfully differentiated infections; 70/178), B. miyamotoi (16.3%; 29/178), and B. valaisiana (15.7%; 28/178), while B. afzelii (40.1%; 91/227), B. spielmanii (21.6%; 49/227), and B. miyamotoi (14.1%; 32/227) occurred most frequently in ticks from cats.

CONCLUSIONS

The differences in pathogen prevalence and Borrelia species distribution between ticks collected from dogs and cats may result from differences in habitat overlap with TBP reservoir hosts. The declining prevalence of A. phagocytophilum with increasing engorgement duration, without a decrease in copy numbers, could indicate transmission to dogs over the time of attachment. The fact that this was not observed in ticks from cats may indicate less efficient transmission. In conclusion, the high prevalence of A. phagocytophilum and Borrelia spp. in ticks collected from dogs and cats underlines the need for effective acaricide tick control to protect both animals and humans from associated health risks.

Tick-borne pathogens in questing adults Dermacentor reticulatus from the Eastern European population (north-eastern Poland)

Dermacentor reticulatus is tick species with an expanding geographical range in Europe, which creates the possibility of spreading microorganisms of significant veterinary and medical importance. The study aimed to investigate the prevalence and genetic diversity of Rickettsia spp., Babesia spp., Borrelia spp. and Anaplasma phagocytophilum in adult D. reticulatus ticks from the Eastern European population in the urban and the natural biotopes of north-eastern Poland. Microorganisms were detected by PCR and identified by DNA sequencing. The overall infection rate of at least one of the pathogens was 29.6%. The predominantly was Rickettsia spp. (27.1%) (with R. raoultii-9.1%) followed by Babesia spp. (2.4%) with B. canis (1.5%) as the most frequent. Based on 18S rRNA gene sequence, three B. canis genotypes were revealed. The prevalence of R. raoultii and B. canis was significantly higher in ticks from natural biotopes. The infection rates of B. afzelii and A. phagocytophilum were determined at 0.9% and 0.3%, respectively. Co-infections were detected in 3.8% of infected ticks. In diagnosing tick-borne diseases in humans, tick-borne lymphadenopathy should not be excluded. The prevalence of different genotypes of B. canis suggests differences in the clinical picture of canine babesiosis in the area.

Canine Babesiosis Caused by Large Babesia Species: Global Prevalence and Risk Factors-A Review

Canine babesiosis is a disease caused by protozoan pathogens belonging to the genus Babesia. Four species of large Babesia cause canine babesiosis (B. canis, B. rossi, B. vogeli, and the informally named B. coco). Although canine babesiosis has a worldwide distribution, different species occur in specific regions: B. rossi in sub-Saharan Africa, B. canis in Europe and Asia, and B. coco in the Eastern Atlantic United States, while B. vogeli occurs in Africa, southern parts of Europe and Asia, northern Australia, southern regions of North America, and in South America. B. vogeli is the most prevalent large Babesia species globally. This results from its wide range of monotropic vector species, the mild or subclinical nature of infections, and likely the longest evolutionary association with dogs. The most important risk factors for infection by large Babesia spp. include living in rural areas, kennels or animal shelters, or regions endemic for the infection, the season of the year (which is associated with increased tick activity), infestation with ticks, and lack of treatment with acaricides.

Babesiosis in Southeastern, Central and Northeastern Europe: An Emerging and Re-Emerging Tick-Borne Disease of Humans and Animals

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.

Tick-Borne Pathogens, Babesia spp. and Borrelia burgdorferi s.l., in Sled and Companion Dogs from Central and North-Eastern Europe

Ticks are important vectors of numerous pathogens of medical and veterinary significance. The aim of the current study was to determine the prevalence of Babesia spp. and Borrelia burgdorferi s.l. in sled and pet dogs from Central and North-Eastern Europe. Neither Babesia spp. nor Borrelia burgdorferi s.l. infections were detected in sled dogs from seven countries (Poland, Lithuania, Latvia, Estonia, Belarus, Russia and Finland). The DNA of Babesia spp. was detected in 100% of symptomatic and 5.4% of asymptomatic pet dogs from Poland. Similarly, the DNA of Babesia spp. was identified in 82% of symptomatic and 3.8% of asymptomatic pet dogs from Ukraine. The DNA of Borrelia burgdorferi s.l. was detected in 4.4% of pet dogs. Molecular typing confirmed the presence of Babesia canis and Borrelia burgdorferi sensu stricto (s.s.) in selected samples. Four dogs were co-infected by B. canis and Borrelia burgdorferi s.l. Tick-borne pathogens constitute a serious health threat to pet dogs in Central and South-Eastern Europe, but were not observed among sled dogs from the same region of Europe nor in the Baltic countries.

Update on prevalence of Babesia canis and Rickettsia spp. in adult and juvenile Dermacentor reticulatus ticks in the area of Poland (2016-2018)

Ornate dog tick, Dermacentor reticulatus is an important vector of Babesia canis, and Rickettsia spp. and other pathogens of veterinary and public health interest. The current study is the first to investigate the long-term changes in prevalence of these pathogens in expanding tick populations in Central Europe. Molecular techniques (PCR, sequencing) were applied for the detection of pathogen DNA in adult (n = 2497) and juvenile ticks (1096 larvae and 410 nymphs). DNA of Rickettsia spp. was identified in 35% of adults and 12.6% of juvenile ticks. DNA of B. canis was detected in 3% of adult ticks and only in ticks from the Eastern region (regional prevalence 6%). As previously, no B. canis-positive ticks were found in Western Poland, including ticks from Wrocław area (n = 298). DNA of B. canis was identified in 0.33% of juvenile ticks (in 3 pools of larvae and 2 nymphs) from the Eastern region. In the current study we confirmed high occurrence of R. raoultii in adults ticks from all four zones and relatively high prevalence of B. canis in the Eastern population of D. reticulatus, corresponding well with high incidence of canine babesiosis in this area of Poland. Finally, we confirmed R. raoultii and B. canis infection in all life stages of D. reticulatus ticks.

The Role of Ticks in the Emergence of Borrelia burgdorferi as a Zoonotic Pathogen and Its Vector Control: A Global Systemic Review

Ticks are widely distributed across the globe, serving as hosts for numerous pathogens that make them major contributors to zoonotic parasitosis. Borrelia burgdorferi is a bacterial species that causes an emerging zoonotic tick-borne disease known as Lyme borreliosis. The role of ticks in the transmission of this pathogen was explored in this study. According to this systematic review, undertaken according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 19 tick species are known to carry Borrelia burgdorferi, with more than half of the recorded cases in the last two decades related to Ixodes ricinus and Ixodes scapularis ticks. Forty-six studies from four continents, Europe, North America, Asia, and Africa, reported this pathogen in ticks collected from vegetation, animals, and humans. This study highlights an increasing distribution of tick-associated Borrelia burgdorferi, likely driven by accelerated tick population increases in response to climate change coupled with tick dispersal via migratory birds. This updated catalogue helps in compiling all tick species responsible for the transmission of B. burgdorferi across the globe. Gaps in research exist on Borrelia burgdorferi in continents such as Asia and Africa, and in considering environmentally friendly vector control strategies in Europe and North America.

Occurrence of juvenile Dermacentor reticulatus ticks in three regions in Poland: the final evidence of the conquest

Background

Two populations of Dermacentor reticulatus ticks (Western and Eastern) in Poland are among the most dynamic tick populations in Central Europe. Expansion and settlement of ticks in new localizations depend on the presence of suitable hosts, for both adult and juvenile ticks.

Methods

The current study was planned to complement our previous studies on questing adult ticks and was focused on a collection of juvenile D. reticulatus ticks from rodents from three regions in Poland, defined by the presence/absence of adult ticks (regions of the Western and Eastern tick population and the gap area between them) to confirm the existence of stable populations. Rodent trapping was conducted in open habitats (fallow lands, wasteland and submerged meadows) in 2016–2018 in June, July and/or August to encompass seasonal peaks of larvae and nymph activity.

Results

Altogether, three tick species were collected, 2866 D. reticulatus, 2141 Ixodes ricinus and 427 Haemaphysalis concinna. Dermacentor reticulatus was the most common (72.3%) and abundant (mean 17.94 ± 2.62 ticks/rodent) tick species on rodents from the Eastern region; in the Western region infestation of rodents was only 6.8%. Ixodes ricinus was found in all three regions and was the only tick species collected from rodents from the gap area. Haemaphysalis concinna was noted only in the Western region. The highest infestation of juvenile D. reticulatus was recorded on voles (Myodes and Microtus spp.), infestation of I. ricinus was the highest on Apodemus mice, and the majority of H. concinna ticks were collected from root voles Alexandromys oeconomus.

Conclusions

Our study confirmed a stable population of D. reticulatus in Eastern and Central Poland and a lower prevalence and mean abundance of this tick species among rodents from the Western region. A lack of juvenile D. reticulatus on rodents in Niewiadów confirmed the existence of the gap area, free of D. reticulatus ticks.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-05039-z.

The specificity of Babesia-tick vector interactions: recent advances and pitfalls in molecular and field studies

Background

Babesia spp. are protozoan parasites of great medical and veterinary importance, especially in the northern Hemisphere. Ticks are known vectors of Babesia spp., although some Babesia-tick interactions have not been fully elucidated.

Methods

The present review was performed to investigate the specificity of Babesia-tick species interactions that have been identified using molecular techniques in studies conducted in the last 20 years under field conditions. We aimed to indicate the main vectors of important Babesia species based on published research papers (n = 129) and molecular data derived from the GenBank database.

Results

Repeated observations of certain Babesia species in specific species and genera of ticks in numerous independent studies, carried out in different areas and years, have been considered epidemiological evidence of established Babesia-tick interactions. The best studied species of ticks are Ixodes ricinus, Dermacentor reticulatus and Ixodes scapularis (103 reports, i.e. 80% of total reports). Eco-epidemiological studies have confirmed a specific relationship between Babesia microti and Ixodes ricinus, Ixodes persulcatus, and Ixodes scapularis and also between Babesia canis and D. reticulatus. Additionally, four Babesia species (and one genotype), which have different deer species as reservoir hosts, displayed specificity to the I. ricinus complex. Eco-epidemiological studies do not support interactions between a high number of Babesia spp. and I. ricinus or D. reticulatus. Interestingly, pioneering studies on other species and genera of ticks have revealed the existence of likely new Babesia species, which need more scientific attention. Finally, we discuss the detection of Babesia spp. in feeding ticks and critically evaluate the data on the role of the latter as vectors.

Conclusions

Epidemiological data have confirmed the specificity of certain Babesia-tick vector interactions. The massive amount of data that has been thus far collected for the most common tick species needs to be complemented by more intensive studies on Babesia infections in underrepresented tick species.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-05019-3.

Tick-Borne Pathogens in Ticks Collected from Wild Ungulates in North-Eastern Poland

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.

Role of Zoo-Housed Animals in the Ecology of Ticks and Tick-Borne Pathogens-A Review

Ticks are ubiquitous ectoparasites, feeding on representatives of all classes of terrestrial vertebrates and transmitting numerous pathogens of high human and veterinary medical importance. Exotic animals kept in zoological gardens, ranches, wildlife parks or farms may play an important role in the ecology of ticks and tick-borne pathogens (TBPs), as they may serve as hosts for local tick species. Moreover, they can develop diseases of varying severity after being infected by TBPs, and theoretically, can thus serve as reservoirs, thereby further propagating TBPs in local ecosystems. The definite role of these animals in the tick-host-pathogen network remains poorly investigated. This review provides a summary of the information currently available regarding ticks and TBPs in connection to captive local and exotic wildlife, with an emphasis on zoo-housed species.