Prevalence of three zoonotic Babesia species in Ixodes ricinus (Linné, 1758) nymphs in a suburban forest in Switzerland

Hazard potential of Swiss Ixodes ricinus ticks: Virome composition and presence of selected bacterial and protozoan pathogens

Ticks play an important role in transmitting many different emerging zoonotic pathogens that pose a significant threat to human and animal health. In Switzerland and abroad, the number of tick-borne diseases, in particular tick-borne encephalitis (TBE), has been increasing over the last few years. Thus, it remains essential to investigate the pathogen spectrum of ticks to rapidly detect emerging pathogens and initiate the necessary measures. To assess the risk of tick-borne diseases in different regions of Switzerland, we collected a total of 10'286 ticks from rural and urban areas in ten cantons in 2021 and 2022. Ticks were pooled according to species, developmental stage, gender, and collection site, and analyzed using next generation sequencing (NGS) and quantitative polymerase chain reaction (qPCR). The metagenomic analysis revealed for the first time the presence of Alongshan virus (ALSV) in Swiss ticks. Interestingly, the pool-prevalence of ALSV was higher than that of tick-borne encephalitis virus (TBEV). Furthermore, several TBEV foci have been identified and pool prevalence of selected non-viral pathogens determined.

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.

Infection rates, species diversity, and distribution of zoonotic Babesia parasites in ticks: a global systematic review and meta-analysis

Zoonotic Babesia species are emerging public health threats globally, and are the cause of a mild to severe malaria-like disease which may be life threatening in immunocompromised individuals. In this study, we determine the global infection rate, distribution, and the diversity of zoonotic Babesia species in tick vectors using a systematic review and meta-analysis. We used the random-effects model to pool data and determined quality of individual studies using the Joanna Briggs Institute critical appraisal instrument for prevalence studies, heterogeneity using Cochran's Q test, and across study bias using Egger's regression test. Herein, we reported a 2.16% (3915/175345, 95% CI: 1.76-2.66) global infection rate of zoonotic Babesia species (B. divergens, B. microti, and B. venatorum) in tick vectors across 36 countries and 4 continents. Sub-group infection rates ranged between 0.65% (95% CI: 0.09-4.49) and 3.70% (95% CI: 2.61-5.21). B. microti was the most prevalent (1.79%, 95% CI: 1.38-2.31) species reported in ticks, while Ixodes scapularis recorded the highest infection rate (3.92%, 95% CI: 2.55-5.99). Larvae 4.18% (95% CI: 2.15-7.97) and females 4.08% (95% CI: 2.56-6.43) were the tick stage and sex with the highest infection rates. The presence of B. divergens, B. microti, and B. venatorum in tick vectors as revealed by the present study suggests possible risk of transmission of these pathogens to humans, especially occupationally exposed population. The control of tick vectors through chemical and biological methods as well as the use of repellants and appropriate clothing by occupationally exposed population are suggested to curtail the epidemiologic, economic, and public health threats associated with this emerging public health crisis.

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.

Global Distribution of Babesia Species in Questing Ticks: A Systematic Review and Meta-Analysis Based on Published Literature

Babesiosis caused by the Babesia species is a parasitic tick-borne disease. It threatens many mammalian species and is transmitted through infected ixodid ticks. To date, the global occurrence and distribution are poorly understood in questing ticks. Therefore, we performed a meta-analysis to estimate the distribution of the pathogen. A deep search for four electronic databases of the published literature investigating the prevalence of Babesia spp. in questing ticks was undertaken and obtained data analyzed. Our results indicate that in 104 eligible studies dating from 1985 to 2020, altogether 137,364 ticks were screened with 3069 positives with an estimated global pooled prevalence estimates (PPE) of 2.10%. In total, 19 different Babesia species of both human and veterinary importance were detected in 23 tick species, with Babesia microti and Ixodesricinus being the most widely reported Babesia and tick species, respectively. Regardless of species, adult ticks with 2.60% had the highest infection rates, while larvae had the least with 0.60%. Similarly, female ticks with 4.90% were infected compared to males with 3.80%. Nested-polymerase chain reaction (PCR) 2.80% had the highest prevalence among the molecular techniques employed. In conclusion, results obtained indicate that Babesia species are present in diverse questing tick species at a low prevalence, of which some are competent vectors.

First detection and molecular identification of Babesia sp. from the giant panda, Ailuropoda melanoleuca, in China

BACKGROUND

Parasitic infections are among the important causes of death of giant pandas (Ailuropoda melanoleuca) that hamper their survival in the wild. There are about 35 species of parasites which have been identified in giant pandas, but no information is currently available regarding the infection of Babesia in giant pandas. Babesia spp. are common intraerythrocytic parasite in wildlife, transmitted by ixodid ticks, which cause babesiosis. Clinical signs of babesiosis include fever, hemolysis, anemia, jaundice and death.

METHODS

A species of Babesia was detected in the blood of a giant panda based on morphology and PCR amplification of the 18S rRNA gene. The phylogenetic relationship of Babesia sp. infecting giant panda was assessed by gene sequence alignment and phylogenetic analysis.

RESULTS

Our analysis revealed that the Babesia isolate detected was most similar to an unidentified species of Babesia identified in black bears (Ursus thibetanus japonicus) from Japan (Babesia sp. Iwate, AB586027.1) with a 99.56% sequence similarity, followed by Babesia sp. EBB (AB566229.1, 99.50%) and Babesia sp. Akita (AB566229.1, 99.07%).

CONCLUSIONS

To our knowledge, this is the first report of Babesia detected in the giant panda. The results indicate that this Babesia sp. may be a novel species, currently named Babesia sp. strain EBP01.

Molecular detection of apicomplexan protozoa in Hokkaido brown bears (Ursus arctos yesoensis) and Japanese black bears (Ursus thibetanus japonicus)

Many tick-borne pathogens (TBPs) are present in wildlife. The objective of this study is to reveal the role of wild bears in maintaining TBPs. A total of 49 brown bears (Ursus arctos yesoensis) from Hokkaido, and 18 Japanese black bears (Ursus thibetanus japonicus) from Tochigi, and 66 Japanese black bears from Nagano were examined by two molecular methods, reverse line blot (RLB) hybridization, and nested PCR. A total of 5 TBPs (Hepatozoon ursi, Babesia sp. UR2-like group, Cytauxzoon sp. UR1, Babesia sp. UR1, and Babesia microti) were detected from bear blood DNA samples. B. microti was detected from blood DNA samples of Japanese black bear for the first time, with the prevalence of 6.0% (5/84). Out of detected pathogens, H. ursi, Babesia sp. UR2-like pathogens, and Cytauxzoon sp. UR1 were considered as three of the most prevalent TBPs in bears. The prevalence of H. ursi were significantly higher in Japanese black bear (0% vs 96.4%) while that of Babesia sp. UR2-like group was higher in Hokkaido brown bears (89.8% vs 40.5%). The prevalence of Babesia sp. UR1 were significantly higher in Japanese black bears from Tochigi (44.4%), comparing with those from Nagano (18.2%). The prevalence of the detected TBPs were significantly higher in adult bears, comparing with those in younger bears. The present study suggests that Japanese bear species contribute in the transmission of several TBPs in Japan. The expanding distribution of bears might cause the accidental transmission of TBPs to humans and domestic animals.

Emergence and Epidemiology of Bovine Babesiosis Due to Babesia divergens on a Northern German Beef Production Farm

Babesia divergens, transmitted by the tick Ixodes ricinus, is the most common cause of bovine babesiosis in northern Europe and plays a role as a zoonotic pathogen. However, several studies have indicated a decline of B. divergens prevalence in Europe during the last decades. Here, we investigate the epidemiology of bovine babesiosis on a beef production farm in northern Germany, which had not been affected by babesiosis until an initial outbreak in 2018. In June 2018, 21 adult cattle died, showing classical symptoms of babesiosis. Babesia divergens merozoites were detected in blood smears of clinically affected animals and the species was confirmed by PCR and sequencing of a part of the 18S rRNA gene. In 2018, screening of the farm's entire stock by PCR revealed that Babesia-positive animals were present in only one of five herds grazing on different pastures. In the following year, further babesiosis cases occurred in multiple herds. In March 2020, 95 cattle were tested for anti-B. divergens antibodies and 36 of them (37.89%) had positive titres. To investigate the local Babesia prevalence in ticks, 1,430 questing I. ricinus ticks (555 larvae, 648 nymphs, 227 adults) were collected on the farm's pastures and subjected to PCR for Babesia detection. Babesia divergens DNA could not be detected, but Babesia microti showed an overall prevalence of 0.49% (7/1,430; 0.88% [2/227] of adult ticks, 0.77% [5/648] of nymphs, 0.00% [0/555] of larvae). Babesia venatorum was detected in 0.42% (6/1,430) of ticks (0.44% [1/227] of adult ticks, 0.77% [5/648] of nymphs, 0.00% [0/555] of larvae) and B. capreoli in 0.07% (1/1,430) of ticks (0.00% [0/227] of adult ticks, 0.15% [1/648] of nymphs, 0.00% [0/555] of larvae). Despite the fact that no B. divergens-positive ticks were found, the collected data suggest a geographical spread of the pathogen on the farm. Bovine babesiosis remains a disease of veterinary importance in Europe and may cause considerable economic losses when (re-)emerging in non-endemic areas, especially as awareness for the disease among veterinarians and farmers declines.

Fatal acute babesiosis associated with Babesia venatorum infection (Babesia sp. EU1) in a captive reindeer calf in Switzerland

Babesia venatorum was isolated from a captive reindeer calf in Switzerland. The clinical signs consistent with acute babesiosis included hemolytic anemia and hemoglobinuria. The diagnosis was made based on visualization of intraerythrocytic parasites in the stained blood smears and confirmed by PCR analysis of the 18S rRNA gene, with subsequent species identification within Babesia confirmed by sequencing. The reindeer calf was initially treated with supportive care and an antiprotozoal drug (imidocarb dipropionate) but died a few days after hospitalization. Babesia venatorum is also known as Babesia sp. EU1 and can infect different mammalian species, including humans. The current case report aims to increase awareness among veterinarians and reindeer owners about the presence and the associated risk of this zoonotic pathogen. Considering the high morbidity and possible mortality associated with acute babesiosis, captive reindeer should receive tick prevention measures and be tested for subclinical infections in endemic area.

Seroprevalence of six pathogens transmitted by the Ixodes ricinus ticks in asymptomatic individuals with HIV infection and in blood donors

The objective of our study was to estimate the seroprevalence of six pathogens transmitted by ticks in HIV-infected persons and blood donors in Poland (B. burgdorferi s.l., A. phagocytophilum, Ehrlichia spp., Babesia spp., Rickettsia spp. Bartonella henselae) to assess the frequency of exposure to such microorganisms in immunocompetent and immunocompromised individuals in endemic regions for I. ricinus ticks. Serum samples were collected from 227 HIV-infected patients and 199 blood donors. All samples were analyzed for antibodies against six tick-borne pathogens and seroprevalence rates were statistically compared between two tested group as well as age, sex and lymphocyte T CD4+ level in HIV infected patients. The seroprevalence of tick-borne infections in HIV-infected patients is higher than that of the healthy population in Poland, although no association between serological status of patients and lymphocyte CD4+ T cell level has been observed. The frequency of tick-borne coinfections and doubtful results of serological tests were significantly higher in HIV-positive individuals. In Poland, the possibility of tick-borne diseases transmission with blood is rather negligible.

The Babesia divergens Asia Lineage Is Maintained through Enzootic Cycles between Ixodes persulcatus and Sika Deer in Hokkaido, Japan

Parasites of the Babesiadivergens Asia lineage, which are closely related to B. divergens in Europe and Babesia sp. strain MO1 in the United States, were recently reported in sika deer (Cervus nippon) in eastern Japan. To identify the tick vector(s) for this parasite, we conducted a field survey in Hokkaido, Japan, where the infection rate in sika deer is the highest in the country. A specific PCR system which detects and discriminates between lineages within B. divergens and between those lineages and Babesia venatorum showed that Ixodes persulcatus (11/822), but not sympatric Ixodes ovatus (0/595) or Haemaphysalis sp. (0/163) ticks, carried B. divergens Asia lineage. Genomic DNA was archived from salivary glands of partially engorged I. persulcatus females and three isolates of B. divergens Asia lineage were newly described. The 18S rRNA gene sequence of the isolates formed the Asia lineage cluster with those previously described in sika deer isolates. One salivary gland also contained parasites of Babesia microti U.S. lineage, which were subsequently isolated in a hamster in vivoB. venatorum (strain Etb5) was also detected in one I. persulcatus tick. The 18S rRNA sequence of Etb5 was 99.7% identical to that of B. venatorum (AY046575) and was phylogenetically positioned in a taxon composed of B. venatorum isolates from Europe, China, and Russia. The geographical distribution of I. persulcatus is consistent with that of B. divergens in sika deer in Japan. These results suggest that I. persulcatus is a principal vector for B. divergens in Japan and Eurasia, where I. persulcatus is predominantly distributed.IMPORTANCE The Babesiadivergens Asia lineage of parasites closely related to B. divergens in Europe and Babesia sp. MO1 in the United States was recently reported in Cervus nippon in eastern Japan. In this study, specific PCR for the Asia lineage identified 11 positives in 822 host-seeking Ixodes persulcatus ticks, a principal vector for many tick-borne disease agents. Gene sequences of three isolates obtained from DNA in salivary glands of female ticks were identical to each other and to those in C. nippon We also demonstrate the coinfection of B. divergens Asia lineage with Babesia microti U.S. lineage in a tick salivary gland and, furthermore, isolated the latter in a hamster. These results suggest that I. persulcatus is the principal vector for B. divergens as well as for B. microti, and both parasites may be occasionally cotransmitted by I. persulcatus This report will be important for public health, since infection may occur through transfusion.

Prevalence of tick-borne pathogens in questing Ixodes ricinus ticks in urban and suburban areas of Switzerland

Background

Throughout Europe, Ixodes ricinus transmits numerous pathogens. Its widespread distribution is not limited to rural but also includes urbanized areas. To date, comprehensive data on pathogen carrier rates of I. ricinus ticks in urban areas of Switzerland is lacking.

Results

Ixodes ricinus ticks sampled at 18 (sub-) urban collection sites throughout Switzerland showed carrier rates of 0% for tick-borne encephalitis virus, 18.0% for Borrelia burgdorferi (sensu lato), 2.5% for Borrelia miyamotoi, 13.5% for Rickettsia spp., 1.4% for Anaplasma phagocytophilum, 6.2% for "Candidatus Neoehrlichia mikurensis", and 0.8% for Babesia venatorum (Babesia sp., EU1). Site-specific prevalence at collection sites with n > 45 ticks (n = 9) significantly differed for B. burgdorferi (s.l.), Rickettsia spp., and "Ca. N. mikurensis", but were not related to the habitat type. Three hundred fifty eight out of 1078 I. ricinus ticks (33.2%) tested positive for at least one pathogen. Thereof, about 20% (71/358) were carrying two or three different potentially disease-causing agents. Using next generation sequencing, we could detect true pathogens, tick symbionts and organisms of environmental or human origin in ten selected samples.

Conclusions

Our data document the presence of pathogens in the (sub-) urban I. ricinus tick population in Switzerland, with carrier rates as high as those in rural regions. Carriage of multiple pathogens was repeatedly observed, demonstrating the risk of acquiring multiple infections as a consequence of a tick bite.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2500-2) contains supplementary material, which is available to authorized users.

Molecular identification and characterization of piroplasm species in Hokkaido sika deer (Cervus nippon yesoensis), Japan

Babesia and Theileria species are tick-borne protozoan parasites that have a veterinary and zoonotic importance. In order to investigate the prevalence and genetic diversity of these parasites, a total of 269 sika deer blood DNA samples collected from Hokkaido, Japan, were examined for Babesia and Theileria species by touch-down PCR targeting the 18S rRNA gene. Reverse line blot (RLB) hybridization was then used to detect 12 piroplasm species. The results revealed that 95.5% (257/269), 94.1% (253/269), 14.1% (38/269), 87.7% (236/269) and 11.5% (31/269) of the examined PCR products hybridized with the probes which were designed to detect all Babesia and Theileria spp., all Theileria spp., all Babesia spp., Theileria sp. Thrivae and Babesia divergens-like, respectively. The 18S rRNA gene partial sequences were divided into Theileria sp. Thrivae, T. capreoli, B. divergens-like and an undescribed Babesia species. This study showed the first detection of the undescribed Babesia sp. from Japan. Therefore, more studies are required to understand the ecology of the newly detected tick-borne pathogens in Hokkaido.

Emergence of tick-borne pathogens (Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, Ricketsia raoultii and Babesia microti) in the Kyiv urban parks, Ukraine

To date, only limited data about the presence of ticks and circulation of tick-borne pathogens in urban parks of Kyiv in northern Ukraine are available. In total, 767 ticks (696 Ixodes ricinus and 69 Dermacentor reticulatus) collected in seven urban parks and one suburban oak wood park in Kyiv were individually analyzed by the PCR assays. Tick-borne pathogens, namely spirochetes from Borrelia burgdorferi sensu lato complex, Anaplasma phagocytophilum, and Babesia microti, were detected in 11.1% of tested I. ricinus ticks. In total, 4% of I. ricinus ticks tested positive for the presence of B. burdorferi s.l. (Borrelia afzelii and Borrelia garinii), 5.2% for A. phagocytophilum, and Ba. microti was confirmed in 1.9% of examined ticks. Mixed infections were recorded in four DNA samples, representing the prevalence of 0.6%. One female and two I. ricinus nymphs were simultaneously infected with B. afzelii and A. phagocytophilum, and one female carried B. afzelii and Ba. microti. In addition, 10.1% of D. reticulatus ticks tested positive for Rickettsia raoultii. Identification of infectious agents and their diversity, assessment of the relative epidemiological importance and determination of the prevalence in questing ticks from central parts of the cities are crucial steps towards the tick-borne diseases surveillance in urban environment.

Dynamics, co-infections and characteristics of zoonotic tick-borne pathogens in Hokkaido small mammals, Japan

Many of the emerging infectious diseases originate in wildlife and many of them are caused by vector-borne pathogens. In Japan, zoonotic tick-borne pathogens (TBPs) are frequently detected in both ticks and wildlife. Here, we studied the infection rates of potentially zoonotic species, including Anaplasma, Ehrlichia, Neoehrlichia and Babesia spp., in Hokkaido's most abundant small mammals as they relate to variable extrinsic factors that might affect the infection rates of these pathogens. A total of 412 small mammals including 64 Apodemus argenteus, 219 Apodemus speciosus, 78 Myodes rufocanus, 41 Myodes rutilus, 6 Myodes rex and 4 Sorex unguiculatus were collected from Furano and Shari sites in Hokkaido, Japan, in 2010 and 2011 and were examined by multiplex PCR for TBPs. A reverse line blot hybridization (RLB) was then developed for the specific detection of 13 potentially zoonotic TBPs. A total of 4 TBPs were detected: Anaplasma sp. AP-sd, Ehrlichia muris, Candidatus Neoehrlichia mikurensis and Babesia microti. The infection rates were 4.4% (18/412), 1.2% (5/412), 13.1% (54/412) and 17.2% (71/412), respectively. The infection rates of each of the detected TBPs were significantly correlated with host small mammal species. A total of 22 (two triple and 20 double) co-infection cases were detected (5.3%). The most frequent co-infection cases occurred between Candidatus N. mikurensis and B. microti 68.2% (15/22). Further studies are required to examine human exposure to these zoonotic TBPs in Hokkaido.

Prevalence and phylogenetic analysis of Babesia spp. in Ixodes ricinus and Ixodes persulcatus ticks in Latvia

Babesia spp. are tick-borne protozoan parasites that have been reported in many European countries and are considered to be emerging pathogens. Several Babesia spp. have been identified in ticks in Latvia. Recently, canine babesiosis cases were diagnosed for the first time in Latvia; therefore, continued studies on the prevalence and occurrence of new species are warranted. In the present study, questing tick samples collected in 2005-2007 were screened for the presence of Babesia spp.; in total, 432 Ixodes ricinus and 693 Ixodes persulcatus ticks were analyzed. Babesia spp. were detected in 1.4% of the I. ricinus ticks and in 1.9% of I. persulcatus ticks. Sequencing revealed that ixodid ticks in Latvia contained Babesia microti, Babesia capreoli, and Babesia venatorum. Babesia microti was the most prevalent species, accounting for 58% of all positive samples; moreover, two distinct B. microti genotypes were identified. Phylogenetic analysis of the full-length 18S rRNA gene of two B. capreoli/B. divergens isolates indicated a closer relationship to the B. capreoli clade than B. divergens. This is the first report of B. venatorum in I. persulcatus ticks in Latvia. Our results suggest that both I. ricinus and I. persulcatus ticks play important roles in the epidemiology of these zoonotic pathogens in Latvia.

Babesia spp. and other pathogens in ticks recovered from domestic dogs in Denmark

Background

Newly recognized endemic foci for human babesiosis include Europe, where Ixodes ricinus, a vector for several species of Babesia, is the most commonly identified tick. Vector-based surveillance provides an early warning system for the emergence of human babesiosis, which is likely to be under-reported at emerging sites. In the present study, we set out to screen I. ricinus collected from Danish domestic dogs for Babesia, in order to identify whether humans in Denmark are exposed to the parasite.

Findings

A total of 661 ticks (Ixodes spp.) were collected from 345 Danish domestic dogs during April-September 2011 and pooled, one sample per dog. DNA was extracted from each sample and examined by PCR and sequencing for Rickettsia spp., Borrelia burgdorferi sensu lato, Bartonella spp., Francisella tularensis, Candidatus Neoehrlichia mikurensis, and Babesia spp. In total, 34% of the samples were positive for tick-borne microorganisms potentially pathogenic to humans: Rickettsia spp. were detected in 16% of the pools, with 79% being R. helvetica. Borrelia burgdorferi sensu lato was found in 15%, with the main species identified as Borrelia afzelii (39%). Likewise, 8% of the samples were positive for Babesia spp. (Babesia microti, 82%; Babesia venatorum (‘EU1’), 18%). Lastly, 1% of the samples tested positive for Candidatus Neoehrlichia mikurensis, and 0.6% for Bartonella spp. No ticks were found to be infected with Francisella tularensis.

Conclusions

Our data are in support of endemic occurrence of potentially zoonotic Babesia in Denmark and confirms I. ricinus as a vector of multiple pathogens of public health concern.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-0843-0) contains supplementary material, which is available to authorized users.

Sympatric occurrence of Ixodes ricinus, Dermacentor reticulatus and Haemaphysalis concinna ticks and Rickettsia and Babesia species in Slovakia

Vojka nad Dunajom in the south-west of the Slovak Republic is a locality with sympatric occurrence of 3 species of ticks. This study investigated the spatial distribution of Dermacentor reticulatus, Ixodes ricinus, and Haemaphysalis concinna ticks in this area and determined the prevalence of Babesia and Rickettsia species in questing adults of these tick species considered as potential risk for humans and animals. Ticks were collected by blanket dragging over the vegetation from September 2011 to October 2012. All ticks were subjected to DNA extraction and individually assayed with PCR-based methods targeting the gltA, sca4, 23S rRNA genes of Rickettsia spp. and the 18S rRNA gene of Babesia spp. D. reticulatus was the dominant species occurring in this area (67.7%, n=600), followed by I. ricinus (31.8%, n=282) and H. concinna (0.5%, n=4) ticks. Rickettsial infection was determined in 10.8% (n=65) and 11.7% (n=33) of D. reticulatus and I. ricinus ticks, respectively. Babesia spp. infection was confirmed in 1.8% (n=11) of D. reticulatus and 0.4% (n=1) of I. ricinus ticks. DNA of 6 different pathogenic tick-borne species, Rickettsia helvetica, Rickettsia monacensis, Rickettsia slovaca, Rickettsia raoultii, Babesia canis, and Babesia venatorum were identified in this locality with sympatric occurrence of I. ricinus, D. reticulatus, and H. concinna ticks.

A molecular survey of Babesia spp. and Theileria spp. in red foxes (Vulpes vulpes) and their ticks from Thuringia, Germany

Wild canines which are closely related to dogs constitute a potential reservoir for haemoparasites by both hosting tick species that infest dogs and harbouring tick-transmitted canine haemoparasites. In this study, the prevalence of Babesia spp. and Theileria spp. was investigated in German red foxes (Vulpes vulpes) and their ticks. DNA extracts of 261 spleen samples and 1953 ticks included 4 tick species: Ixodes ricinus (n=870), I. canisuga (n=585), I. hexagonus (n=485), and Dermacentor reticulatus (n=13) were examined for the presence of Babesia/Theileria spp. by a conventional PCR targeting the 18S rRNA gene. One hundred twenty-one out of 261 foxes (46.4%) were PCR-positive. Out of them, 44 samples were sequenced, and all sequences had 100% similarity to Theileria annae. Similarly, sequencing was carried out for 65 out of 118 PCR-positive ticks. Theileria annae DNA was detected in 61.5% of the sequenced samples, Babesia microti DNA was found in 9.2%, and Babesia venatorum in 7.6% of the sequenced samples. The foxes were most positive in June and October, whereas the peak of tick positivity was in October. Furthermore, the positivity of the ticks was higher for I. canisuga in comparison to the other tick species and for nymphs in comparison to adults. The high prevalence of T. annae DNA in red foxes in this study suggests a reservoir function of those animals for T. annae. To our knowledge, this is the first report of T. annae in foxes from Germany as well as the first detection of T. annae and B. microti in the fox tick I. canisuga. Detection of DNA of T. annae and B. microti in three tick species collected from foxes adds new potential vectors for these two pathogens and suggests a potential role of the red fox in their natural endemic cycles.

Natural history of Zoonotic Babesia: Role of wildlife reservoirs

Babesiosis is an emerging zoonotic disease on all inhabited continents and various wildlife species are the principal reservoir hosts for zoonotic Babesia species. The primary vectors of Babesia are Ixodid ticks, with the majority of zoonotic species being transmitted by species in the genus Ixodes. Species of Babesia vary in their infectivity, virulence and pathogenicity for people. Various factors (e.g., increased interactions between people and the environment, increased immunosuppression, changes in landscape and climate, and shifts in host and vector species abundance and community structures) have led to an increase in tick-borne diseases in people, including babesiosis. Furthermore, because babesiosis is now a reportable disease in several states in the United States, and it is the most common blood transfusion-associated parasite, recognized infections are expected to increase. Because of the zoonotic nature of these parasites, it is essential that we understand the natural history (especially reservoirs and vectors) so that appropriate control and prevention measures can be implemented. Considerable work has been conducted on the ecology of Babesia microti and Babesia divergens, the two most common causes of babesiosis in the United States and Europe, respectively. However, unfortunately, for many of the zoonotic Babesia species, the reservoir(s) and/or tick vector(s) are unknown. We review the current knowledge regarding the ecology of Babesia among their reservoir and tick hosts with an emphasis of the role on wildlife as reservoirs. We hope to encourage the molecular characterization of Babesia from potential reservoirs and vectors as well from people. These data are necessary so that informed decisions can be made regarding potential vectors and the potential role of wildlife in the ecology of a novel Babesia when it is detected in a human patient.

Human babesiosis in Europe: what clinicians need to know

Although best known as an animal disease, human babesiosis is attracting increasing attention as a worldwide emerging zoonosis. Humans are commonly infected by the bite of ixodid ticks. Rare ways of transmission are transplacental, perinatal and transfusion-associated. Infection of the human host can cause a very severe host-mediated pathology including fever, and hemolysis leading to anemia, hyperbilirubinuria, hemoglobinuria and possible organ failure. In recent years, apparently owing to increased medical awareness and better diagnostic methods, the number of reported cases in humans is rising steadily worldwide. Hitherto unknown zoonotic Babesia spp. are now being reported from geographic areas where babesiosis was not previously known to occur and the growing numbers of travelers and immunocompromised individuals suggest that the frequency of cases in Europe will also continue to rise. Our review is intended to provide clinicians with practical information on the clinical management of this rare, but potentially life-threatening zoonotic disease. It covers epidemiology, phylogeny, diagnostics and treatment of human babesiosis and the potential risk of transfusion-transmitted disease with a special focus on the European situation.

Serum antibodies to Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti in recaptured white-footed mice

A mark-release-recapture study was conducted during 2007 through 2010 in six, tick-infested sites in Connecticut, United States to measure changes in antibody titers for Borrelia burgdorferi sensu stricto, Anaplasma phagocytophilum, and Babesia microti in Peromyscus leucopus (white-footed mice). There was an overall recapture rate of 40%, but only four tagged mice were caught in ≥2 yr. Sera from 561 mice were analyzed for total antibodies to B. burgdorferi and A. phagocytophilum by using whole-cell or recombinant (VlsE or protein 44) antigens in a solid-phase enzyme-linked immunosorbent assay or to whole-cell B. microti by indirect fluorescent antibody staining. Antibody prevalences were highly variable for B. burgdorferi (from 56% to 98%), A. phagocytophilum (from 11% to 85%), and B. microti (from 11% to 84%) depending on the site and time of sampling. Of 463 mice with antibodies, 206 (45%) had antibodies to all three pathogens. Changes in antibody status for some mice from negative to positive (117 seroconversions) or from positive to negative (55 reversions) were observed. Seroconversions were observed in 10.1% of 417 mice for B. burgdorferi, 18.0% of 306 mice for A. phagocytophilum, and 6.6% of 304 mice for B. microti; reversion rates were 5.3, 5.9, and 4.9%, respectively. Antibodies to all pathogens persisted in some mice over several weeks while, in others, there were marked declines in titration end points to negative status. The latter may indicate elimination of a certain pathogen, such as A. phagocytophilum, or that mouse immune systems ceased to produce antibodies despite an existing patent infection.

Questing Dermacentor reticulatus harbouring Babesia canis DNA associated with outbreaks of canine babesiosis in the Swiss Midlands

In 2011 and 2012, outbreaks of clinical canine babesiosis were observed in 2 areas of the Swiss Midlands that had no history of this disease so far. In one area, cases of canine babesiosis occurred over 2 consecutive tick seasons. The outbreaks involved 29 dogs, 4 of which died. All dogs were infected with large Babesia sp. as diagnosed in Giemsa-stained blood smears and/or PCR. These were identified as B. canis (formerly known as B. canis canis) by subsequent partial sequencing of the 18S rRNA gene of Babesia sp. Interestingly, the sequence indicated either a genotype with heterogeneity in the ssrRNA gene copies or double infection with different B. canis isolates. None of the dogs had a recent travel history, but one had frequently travelled to Hungary and had suffered twice from clinical babesiosis 18 and 24 months prior to the outbreak in autumn 2011. Retrospective sequencing of a stored blood DNA sample of this dog revealed B. canis, with an identical sequence to the Babesia involved in the outbreaks. For the first time in Switzerland, the partial 18S rRNA gene of B. canis could be amplified from DNA isolated from 19 out of 23 adult Dermacentor reticulatus ticks flagged in the same area. The sequence was identical to that found in the dogs. Furthermore, one affected dog carried a female D. reticulatus tick harbouring B. canis DNA. Our findings illustrate that, under favourable biogeographic and climatic conditions, the life-cycle of B. canis can relatively rapidly establish itself in previously non-endemic areas. Canine babesiosis should therefore always be a differential diagnosis when dogs with typical clinical signs are presented, regardless of known endemic areas.

First detection of Ixodes ricinus on beef cattle in Israel

This is the first report of the presence of Ixodes ricinus on beef cattle in Israel. Up to now, in the Middle East this tick was considered to be confined to Turkey and northern Iran. In the present study, tick samples collected from field-grazing beef cattle in western Galilee (northern Israel) were first examined morphologically for species-specific taxonomical features and then by molecular characterization. Ticks identified morphologically as I. ricinus were then examined by PCR with four different molecular markers: 12S rRNA, 16S rRNA, COX1 and cytochrome B. The PCR products were sequenced and compared with annotated I. ricinus sequences in GenBank™ and the analyzed sequences from the collected samples shared 98-99% identity with reported I. ricinus sequences. In contrast, sequences from the collected ticks shared identity of 91% or less with annotated sequences from other Ixodes species. Multiple alignments and neighbor-joining analyses performed for each of the four markers reinforced the results obtained from pairwise alignments. These findings demonstrated for the first time the presence in Israel of the tick species I. ricinus - with results confirmed by a combination of morphological examination and molecular analyses.

Infections and coinfections of questing Ixodes ricinus ticks by emerging zoonotic pathogens in Western Switzerland

In Europe, Ixodes ricinus is the vector of many pathogens of medical and veterinary relevance, among them Borrelia burgdorferi sensu lato and tick-borne encephalitis virus, which have been the subject of numerous investigations. Less is known about the occurrence of emerging tick-borne pathogens like Rickettsia spp., Babesia spp., "Candidatus Neoehrlichia mikurensis," and Anaplasma phagocytophilum in questing ticks. In this study, questing nymph and adult I. ricinus ticks were collected at 11 sites located in Western Switzerland. A total of 1,476 ticks were analyzed individually for the simultaneous presence of B. burgdorferi sensu lato, Rickettsia spp., Babesia spp., "Candidatus Neoehrlichia mikurensis," and A. phagocytophilum. B. burgdorferi sensu lato, Rickettsia spp., and "Candidatus Neoehrlichia mikurensis" were detected in ticks at all sites with global prevalences of 22.5%, 10.2%, and 6.4%, respectively. Babesia- and A. phagocytophilum-infected ticks showed a more restricted geographic distribution, and their prevalences were lower (1.9% and 1.5%, respectively). Species rarely reported in Switzerland, like Borrelia spielmanii, Borrelia lusitaniae, and Rickettsia monacensis, were identified. Infections with more than one pathogenic species, involving mostly Borrelia spp. and Rickettsia helvetica, were detected in 19.6% of infected ticks. Globally, 34.2% of ticks were infected with at least one pathogen. The diversity of tick-borne pathogens detected in I. ricinus in this study and the frequency of coinfections underline the need to take them seriously into consideration when evaluating the risks of infection following a tick bite.