Substantial Rise in the Prevalence of Lyme Borreliosis Spirochetes in a Region of Western Germany over a 10-Year Period

More than a decade after a study on the transmission cycle of Borrelia burgdorferi sensu lato in the Siebengebirge, a nature reserve near Bonn, Germany, questing nymphal and adult Ixodes ricinus ticks were collected again in three selected areas of the same low mountain range and examined for infection with B. burgdorferi sensu lato. Between May and October 2001, a total of 1,754 ticks were collected by blanket dragging; 374 ticks were analyzed for B. burgdorferi sensu lato by both an immunofluorescence assay (IFA) and at least two different PCR tests, whereas 171 ticks were analyzed by PCR only. By combining all assays, an average of 14% of the ticks tested positive for B. burgdorferi sensu lato, 5.5, 15.8, and 21.8% in the three collection areas. Of the nymphs and adults examined, 12.9 and 21.1%, respectively, were found to be spirochete infected. A lower total infection prevalence was obtained by IFA (14.4%) than by a nested PCR approach (16.5%), but both were higher than that obtained by a simple PCR approach (11.9%). Compared with data collected over a decade ago, the mean infection prevalence of B. burgdorferi sensu lato in the ticks was significantly higher for all three biotopes, whereas a similar pattern of habitat-specific infection prevalence was observed. Genotyping of B. burgdorferi sensu lato revealed high relative prevalences of B. valaisiana (identified in 43.1% of infected ticks) and B. garinii (32.3%), whereas B. afzelii (12.3%) and B. burgdorferi sensu stricto (1.5%) were relatively rare. We conclude that B. burgdorferi sensu lato infection has increased in this region over the last 15 years due to presently unknown changes in ecological conditions, perhaps related to climate change or wildlife management.     

Local variations in the distribution and prevalence of Borrelia burgdorferi sensu lato genomospecies in Ixodes ricinus ticks.

Unfed nymphal and adult Ixodes ricinus ticks were collected from five locations within the 10,000-ha Killarney National Park, Ireland. The distribution and prevalence of the genomospecies of Borrelia burgdorferi sensu lato in the ticks were investigated by PCR amplification of the intergenic spacer region between the 5S and 23S rRNA genes and by reverse line blotting with genomospecies-specific oligonucleotide probes. The prevalence of ticks infected with B. burgdorferi sensu lato was significantly variable between the five locations, ranging from 11.5 to 28.9%. Four genomospecies were identified as B. burgdorferi sensu stricto, Borrelia afzelii, Borrelia garinii, and VS116. Additionally, untypeable B. burgdorferi sensu lato genomospecies were identified in two nymphs. VS116 was the most prevalent of the genomospecies and was identified in 50% of the infected ticks. Prevalences of B. garinii and B. burgdorferi sensu stricto were similar (17 and 18%, respectively); however, significant differences were observed in the prevalence of these genomospecies in mixed infections (58.8 and 23.5%, respectively). Notably, the prevalence of B. afzelii was low, comprising 9.6 and 7.4%, respectively, of single and mixed infections. Significant variability was observed in the distribution and prevalence of B. burgdorferi sensu lato genomospecies between locations in the park, and the diversity and prevalence of B. burgdorferi sensu lato genomospecies was typically associated with woodland. The distributions of B. burgdorferi sensu lato genomospecies were similar in wooded areas and in areas bordering woodland, although the prevalence of B. burgdorferi sensu lato infection was typically reduced. Spatial distributions vegetation composition, and host cenosis of the habitats were identified as factors which may affect the distribution and prevalence of B. burgdorferi sensu lato genomospecies within the park.     

Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, Francisella tularensis and their co-infections in host-seeking Ixodes ricinus ticks collected in Serbia

To evaluate the prevalence rate of tick-borne bacterial pathogens, unfed adult Ixodes ricinus ticks were collected from vegetation in 2001, 2003, and 2004 at 18 localities throughout Serbia. A total of 287 ticks were examined by PCR technique for the presence of Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, and Francisella tularensis. The highest prevalence rate was that for B. burgdorferi sensu lato (42.5%), followed by A. phagocytophilum (13.9%) and F. tularensis (3.8%). The presence of five B. burgdorferi sensu lato genospecies, namely, B. burgdorferi sensu stricto, B. afzelii, B. garinii, B. lusitaniae, and B. valaisiana was identified by restriction fragment length polymorphism (RFLP) analysis. The most frequent B. burgdorferi sensu lato genospecies was B. lusitaniae, followed by B. burgdorferi sensu stricto. Co-infection by B. burgdorferi sensu stricto and B. lusitaniae was frequently observed. Co-infection by B. burgdorferi sensu lato and A. phagocytophilum and co-infection by B. burgdorferi sensu lato and F. tularensis appeared in 24 ticks. Sequencing of p44/msp2 paralogs of Serbian A. phagocytophilum showed that they were unique and distinct from those of A. phagocytophilum in US and UK. This is the first report of B. garinii, B. lusitaniae, B. valaisiana, as well as A. phagocytophilum and F. tularensis infected ticks in Serbia. These findings indicate a public health threat in Serbia of tick-borne diseases caused by B. burgdorferi sensu lato, A. phagocytophilum and F. tularensis.     

Introduced Siberian chipmunks (Tamias sibiricus barberi) harbor more-diverse Borrelia burgdorferi sensu lato genospecies than native bank voles (Myodes glareolus)

Little attention has been given in scientific literature to how introduced species may act as a new host for native infectious agents and modify the epidemiology of a disease. In this study, we investigated whether an introduced species, the Siberian chipmunk (Tamias sibiricus barberi), was a potentially new reservoir host for Borrelia burgdorferi sensu lato, the causative agent of Lyme disease. First, we ascertained whether chipmunks were infected by all of the B. burgdorferi sensu lato genospecies associated with rodents and available in their source of infection, questing nymphs. Second, we determined whether the prevalence and diversity of B. burgdorferi sensu lato in chipmunks were similar to those of a native reservoir rodent, the bank vole (Myodes glareolus). Our research took place between 2006 and 2008 in a suburban French forest, where we trapped 335 chipmunks and 671 voles and collected 743 nymphs of ticks that were questing for hosts by dragging on the vegetation. We assayed for B. burgdorferi sensu lato with ear biopsy specimens taken from the rodents and in nymphs using PCR and restriction fragment length polymorphism (RFLP). Chipmunks were infected by the three Borrelia genospecies that were present in questing nymphs and that infect rodents (B. burgdorferi sensu stricto, B. afzelii, and B. garinii). In contrast, voles hosted only B. afzelii. Furthermore, chipmunks were more infected (35%) than voles (16%). These results may be explained by the higher exposure of chipmunks, because they harbor more ticks, or by their higher tolerance of other B. burgdorferi sensu lato genospecies than of B. afzelii. If chipmunks are competent reservoir hosts for B. burgdorferi sensu lato, they may spill back B. burgdorferi sensu lato to native communities and eventually may increase the risk of Lyme disease transmission to humans.     

Occurrence of multiple infections with different Borrelia burgdorferi genospecies in Danish Ixodes ricinus nymphs

The pathogen Borrelia burgdorferi causes Lyme Borreliosis in human and animals world-wide. In Europe the pathogen is transmitted to the host by the vector Ixodes ricinus. The nymph is the primary instar for transmission to humans. We here study the infection rate of five Borrelia genospecies: B. burgdorferi sensu stricto, B. afzelii, B. garinii, B. valaisiana, B. lusitaniae in nymphs, by IFA and PCR. 600 nymphs were collected in North Zealand of Denmark. Each nymph was first analysed by IFA. If positive for spirochaetal infection, the genospecies was determined by PCR. The infection rate of B. burgdorferi sensu lato was 15.5%, with the primary genospecies being B. afzelii (64.3%), B. garinii (57.1%), and B. lusitaniae (26.8%). It is the first time B. lusitaniae is documented in Denmark. Even though, the highest infection rate was discovered for B. afzelii and B. garinii, mixed infections are more common than single infections. Fifty-one percent (29/56) of these were infected with two genospecies, 7.1% (4/56) with three, and 5.3% (3/56) with four. We try to explain the high infection rate and the peculiar number of multiple infections, with a discussion of changes host abundance and occurrence of different transmission patterns.     

Prevalence of Borrelia burgdorferi sensu lato and Anaplasmataceae members in Ixodes ricinus ticks in Alsace, a focus of Lyme borreliosis endemicity in France

Due to the high Lyme borreliosis incidence in Alsace, in northeastern France, we investigated in 2003-2004 three cantons in this region in order to determine the density of Ixodes ricinus ticks infected by Borrelia burgdorferi sensu lato and Anaplasmataceae. The peak density of nymphs infected by B. burgdorferi sensu lato at Munster and Guebwiller, where the disease incidence was high, was among the highest reported in Europe (105 and 114 per 100 m(2), respectively). In contrast, the peak density of infected nymphs was low in the canton of Dannemarie (5/100 m(2)), where the disease incidence was low. The two main species detected in ticks were Borrelia afzelii, more frequent in nymphs, and Borrelia garinii, more frequent in adult ticks. The rates of tick infection by Anaplasma phagocytophilum were 0.4% and 1.2% in nymphs and adults, respectively.     

Identification of a new Borrelia species among small mammals in areas of northern Spain where Lyme disease is endemic

The role of small mammals as reservoir hosts for Borrelia burgdorferi was investigated in several areas where Lyme disease is endemic in northern Spain. A low rate of infestation by Ixodes ricinus nymphs was found in the small mammal populations studied that correlated with the near-absence of B. burgdorferi sensu lato in 184 animals tested and with the lack of transmission of B. burgdorferi sensu lato to I. ricinus larvae that fed on them. In contrast, questing ticks collected at the same time and in the same areas were found to carry a highly variable B. burgdorferi sensu lato repertoire (B. burgdorferi sensu stricto, Borrelia garinii, Borrelia valaisiana, and Borrelia afzelii). Interestingly, the only isolate obtained from small mammals (R57, isolated from a bank vole) grouped by phylogenetic analyses with other Borrelia species but in a separate clade from the Lyme disease and relapsing fever organisms, suggesting that it is a new species. This new agent was widely distributed among small mammals, with infection rates of 8.5 to 12% by PCR. Moreover, a high seroprevalence to B. burgdorferi sensu lato was found in the animal sera, suggesting cross-reactivity between B. burgdorferi sensu lato and R57. Although small mammals do not seem to play an important role as reservoirs for B. burgdorferi sensu lato in the study area, they seem to be implicated in the maintenance of spirochetes similar to R57.     

Factors driving the abundance of ixodes ricinus ticks and the prevalence of zoonotic I. ricinus-borne pathogens in natural foci

Environmental factors may drive tick ecology and therefore tick-borne pathogen (TBP) epidemiology, which determines the risk to animals and humans of becoming infected by TBPs. For this reason, the aim of this study was to analyze the influence of environmental factors on the abundance of immature-stage Ixodes ricinus ticks and on the prevalence of two zoonotic I. ricinus-borne pathogens in natural foci of endemicity. I. ricinus abundance was measured at nine sites in the northern Iberian Peninsula by dragging the vegetation with a cotton flannelette, and ungulate abundance was measured by means of dung counts. In addition to ungulate abundance, data on variables related to spatial location, climate, and soil were gathered from the study sites. I. ricinus adults, nymphs, and larvae were collected from the vegetation, and a representative subsample of I. ricinus nymphs from each study site was analyzed by PCR for the detection of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum DNA. Mean prevalences of these pathogens were 4.0% ± 1.8% and 20.5% ± 3.7%, respectively. Statistical analyses confirmed the influence of spatial factors, climate, and ungulate abundance on I. ricinus larva abundance, while nymph abundance was related only to climate. Interestingly, cattle abundance rather than deer abundance was the main driver of B. burgdorferi sensu lato and A. phagocytophilum prevalence in I. ricinus nymphs in the study sites, where both domestic and wild ungulates coexist. The increasing abundance of cattle seems to increase the risk of other hosts becoming infected by A. phagocytophilum, while reducing the risk of being infected by B. burgdorferi sensu lato. Controlling ticks in cattle in areas where they coexist with wild ungulates would be more effective for TBP control than reducing ungulate abundance.     

Molecular identification and analysis of Borrelia burgdorferi sensu lato in lizards in the southeastern United States

Lyme borreliosis (LB) group spirochetes, collectively known as Borrelia burgdorferi sensu lato, are distributed worldwide. Wild rodents are acknowledged as the most important reservoir hosts. Ixodes scapularis is the primary vector of B. burgdorferi sensu lato in the eastern United States, and in the southeastern United States, the larvae and nymphs mostly parasitize certain species of lizards. The primary aim of the present study was to determine whether wild lizards in the southeastern United States are naturally infected with Lyme borreliae. Blood samples obtained from lizards in Florida and South Carolina were tested for the presence of LB spirochetes primarily by using B. burgdorferi sensu lato-specific PCR assays that amplify portions of the flagellin (flaB), outer surface protein A (ospA), and 66-kDa protein (p66) genes. Attempts to isolate spirochetes from a small number of PCR-positive lizards failed. However, PCR amplification and sequence analysis of partial flaB, ospA, and p66 gene fragments confirmed numerous strains of B. burgdorferi sensu lato, including Borrelia andersonii, Borrelia bissettii, and B. burgdorferi sensu stricto, in blood from lizards from both states. B. burgdorferi sensu lato DNA was identified in 86 of 160 (54%) lizards representing nine species and six genera. The high infection prevalence and broad distribution of infection among different lizard species at different sites and at different times of the year suggest that LB spirochetes are established in lizards in the southeastern United States.     

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.     

Wild turkey (Meleagris gallopavo) as a host of ixodid ticks, lice, and Lyme disease spirochetes (Borrelia burgdorferi sensu lato) in California state parks

Rio Grande wild turkeys (Meleagris gallopavo intermedia) were evaluated as potential hosts of ixodid ticks, lice, and Lyme disease spirochetes (Borrelia burgdorferi sensu lato [s.l.]) in three state parks in Sonoma County, California, USA, during 2003 and 2004. In total, 113 birds were collected, 50 (44.2%) of which were found to be infested by 361 ixodid ticks representing three species: the western black-legged tick (Ixodes pacificus, n=248), the rabbit tick (Haemaphysalis leporispalustris, n=112), and one American dog tick (Dermacentor variabilis). Year-round the prevalence of all ticks combined was unrelated to the age or sex of turkeys, and the prevalence of infestation by I. pacificus (35.4%) was significantly higher than it was for either H. leporispalustris (14.2%) or D. variabilis (0.9%). The proportion of the two prevalent tick species differed significantly by life stage with 86.3% of the I. pacificus and 82.1% of the H. leporispalustris enumerated being nymphs and larvae, respectively. Three species of lice were collected, including the chicken body louse Menacanthus stramineus (12.5% of total), Chelopistes meleagridis (37.5% of total), and Oxylipeurus polytrapezius (50% of total). The records for all three ticks are the first ever from wild turkeys, and those for the lice are the first from this host in the far-western United States. Wild turkeys potentially were exposed to the feeding activities of I. pacificus nymphs infected with B. burgdorferi s.l. as 15% of host-seeking nymphs (n=200) collected in woodlands used by turkeys as roosting or foraging areas were infected mainly with B. burgdorferi sensu stricto (s.s.). However, only one (1%) of 90 turkey blood specimens tested by PCR contained B. burgdorferi s.s., and four in vitro, complement-protein assays demonstrated that domestic turkey serum is moderately bacteriolytic for this spirochete. Taken together, these findings indicate that wild turkeys are important avian hosts of I. pacificus nymphs, but they appear to be inconsequential hosts of B. burgdorferi s.l.     

Association of Borrelia garinii and B. valaisiana with songbirds in Slovakia

In Europe, 6 of the 11 genospecies of Borrelia burgdorferi sensu lato are prevalent in questing Ixodes ricinus ticks. In most parts of Central Europe, B. afzelii, B. garinii, and B. valaisiana are the most frequent species, whereas B. burgdorferi sensu stricto, B. bissettii, and B. lusitaniae are rare. Previously, it has been shown that B. afzelii is associated with European rodents. Therefore, the aim of this study was to identify reservoir hosts of B. garinii and B. valaisiana in Slovakia. Songbirds were captured in a woodland near Bratislava and investigated for engorged ticks. Questing I. ricinus ticks were collected in the same region. Both tick pools were analyzed for spirochete infections by PCR, followed by DNA-DNA hybridization and, for a subsample, by nucleotide sequencing. Three of the 17 captured songbird species were infested with spirochete-infected ticks. Spirochetes in ticks that had fed on birds were genotyped as B. garinii and B. valaisiana, whereas questing ticks were infected with B. afzelii, B. garinii, and B. valaisiana. Furthermore, identical ospA alleles of B. garinii were found in ticks that had fed on the birds and in questing ticks. The data show that songbirds are reservoir hosts of B. garinii and B. valaisiana but not of B. afzelii. This and previous studies confirm that B. burgdorferi sensu lato is host associated and that this bacterial species complex contains different ecotypes.     

Improving the specificity of 16S rDNA-based polymerase chain reaction for detecting Borrelia burgdorferi sensu lato-causative agents of human Lyme disease

AIMS: 16S rDNA sequences of Borrelia burgdorferi sensu lato were aligned with the 16S rDNA sequences of Borrelia hermsii, Borrelia turicatae, and Borrelia lonestari in order to identify primers that might be used to more specifically identify agents of human Lyme disease in ticks in human skin samples. METHODS AND RESULTS: Standard polymerase chain reaction (PCR), using an oligonucleotide sequence, designated TEC1, was shown, in combination with a previously developed primer (LD2) to amplify strains of B. burgdorferi sensu stricto, Borrelia afzelii, and Borrelia garinii, but not the non-Lyme causing B. hermsii or B. turicatae. This primer pair, designated Bbsl, was successfully used to amplify B. burgdorferi sensu lato from skin biopsies of patients with Lyme disease symptoms as well as from Ixodes scapularis, Amblyomma americanum and Dermacentor variabilis ticks. CONCLUSIONS: The primer set Bbsl allows for the rapid detection and differentiation of B. burgdorferi sensu lato from non-Lyme disease-causing Borrelia species in ticks and human tissues. SIGNIFICANCE AND IMPACT OF THE STUDY: The PCR primer set, Bbsl, will greatly facilitate detection of the causative agents of Lyme disease in infected ticks and human skin samples assisting in epidemiological studies, and potentially allowing for a more rapid diagnosis of the disease in patients.     

Prevalence of Borrelia burgdorferi sensu lato in ticks collected from migratory birds in Switzerland

The prevalence of ticks infected by Borrelia burgdorferi sensu lato on birds during their migrations was studied in Switzerland. A total of 1,270 birds captured at two sites were examined for tick infestation. Ixodes ricinus was the dominant tick species. Prevalences of tick infestation were 6% and 18.2% for birds migrating northward and southward, respectively. Borrelia valaisiana was the species detected most frequently in ticks, followed by Borrelia garinii and Borrelia lusitaniae. Among birds infested by infected ticks, 23% (6/26) were infested by B. lusitaniae-infected larvae. Migratory birds appear to be reservoir hosts for B. lusitaniae.     

Comparative evaluation of the efficacy of Borrelia indication in ixodes ticks (Ixodidae) using dark field microscopy and polymerase chain reaction (PCR)

Indication of Borrelia (B. burgdorferi sensu lato) in 205 adult unfed I. persulcatus ticks from a natural focus was carried out simultaneously by methods of PCR and dark-field microscopy of vital preparations. PCR method revealed Borrelia prevalence in considerable number of ticks, in which Borrelia were not found by microscopy of 250 microscopic fields in a preparation from each individual tick. At the same time, PCR method didn't give positive results for approximately 8% of ticks, which contained rather high concentration of Borrelia (more than 10 per 100 microscopic fields). In general, PCR method doesn't have advantages in comparison with a microscopy of vital preparations for study the Borrelia prevalence in ticks.     

Geographic distribution of white-tailed deer with ticks and antibodies to Borrelia burgdorferi in Connecticut.

Ticks and blood specimens were collected from white-tailed deer (Odocoileus virginianus) in Connecticut and analyzed to identify foci for Lyme borreliosis. Males and females of Ixodes scapularis, the chief vector of Borrelia burgdorferi, were collected from deer in five of eight counties during 1989-1991. Analysis by indirect fluorescent antibody (IFA) staining of midgut tissues showed that prevalence of infection was highest (9.5% of 367 ticks) in south central and southeastern Connecticut. Infected I. scapularis also were collected from southwestern regions of the state (12.1% of 99 ticks), but prevalence of infection in northern counties was considerably lower (0.8% of 124 ticks). Deer sera, obtained in 1980 and 1989-1991, were analyzed by an enzyme-linked immunosorbent assay or by IFA staining methods. Antibodies to B. burgdorferi were detected in sera collected from all eight counties in Connecticut. Deer had been infected by this spirochete in at least 50 towns, 17 (34%) of which are in south central and southeastern parts of the state. Borrelia burgdorferi is widely distributed in I. scapularis populations in Connecticut.     

Coexistence of emerging bacterial pathogens in Ixodes ricinus ticks in Serbia

The list of tick-borne pathogens is long, varied and includes viruses, bacteria, protozoa and nematodes. As all of these agents can exist in ticks, their co-infections have been previously reported. We studied co-infections of emerging bacterial pathogens (Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum and Francisella tularensis) in Ixodes ricinus ticks in Serbia. Using PCR technique, we detected species-specific sequences, rrf-rrl rDNA intergenic spacer for B. burgdorferi s.l., p44/msp2 paralogs for A. phagocytophilum, and the 17 kDa lipoprotein gene, TUL4, for F. tularensis, respectively, in total DNA extracted from the ticks. Common infections with more than one pathogen were detected in 42 (28.8%) of 146 infected I. ricinus ticks. Co-infections with two pathogens were present in 39 (26.7%) of infected ticks. Simultaneous presence of A. phagocytophilum and different genospecies of B. burgdorferi s.l. complex was recorded in 16 ticks, co-infection with different B. burgdorferi s. l. genospecies was found in 15 ticks and eight ticks harbored mixed infections with F. tularensis and B. burgdorferi s.l. genospecies. Less common were triple pathogen species infections, detected in three ticks, one infected with A. phagocytophilum / B. burgdorferi s.s. / B. lusitaniae and two infected with F. tularensis / B. burgdorferi s.s. / B. lusitaniae. No mixed infections of A. phagocytophilum and F. tularensis were detected.     

Prevalence of Borrelia burgdorferi sensu lato genospecies in Ixodes ricinus ticks in Europe: a metaanalysis

In Europe, Borrelia burgdorferi genospecies causing Lyme borreliosis are mainly transmitted by the tick Ixodes ricinus. Since its discovery, B. burgdorferi has been the subject of many epidemiological studies to determine its prevalence and the distribution of the different genospecies in ticks. In the current study we systematically reviewed the literature on epidemiological studies of I. ricinus ticks infected with B. burgdorferi sensu lato. A total of 1,186 abstracts in English published from 1984 to 2003 were identified by a PubMed keyword search and from the compiled article references. A multistep filter process was used to select relevant articles; 110 articles from 24 countries contained data on the rates of infection of I. ricinus with Borrelia in Europe (112,579 ticks), and 44 articles from 21 countries included species-specific analyses (3,273 positive ticks). These data were used to evaluate the overall rate of infection of I. ricinus with Borrelia genospecies, regional distributions within Europe, and changes over time, as well as the influence of different detection methods on the infection rate. While the infection rate was significantly higher in adults (18.6%) than in nymphs (10.1%), no effect of detection method, tick gender, or collection period (1986 to 1993 versus 1994 to 2002) was found. The highest rates of infection of I. ricinus were found in countries in central Europe. B. afzelii and B. garinii are the most common Borrelia species, but the distribution of genospecies seems to vary in different regions in Europe. The most frequent coinfection by Borrelia species was found for B. garinii and B. valaisiana.     

Columbian black-tailed deer (Odocoileus hemionus columbianus) as hosts for Borrelia spp. in northern California

The prevalence of infection of Columbian black-tailed deer (Odocoileus hemionus columbianus) with Borrelia spp. was evaluated in an area of northwestern California (USA) where Lyme disease is endemic and the relapsing-fever group spirochete Borrelia coriaceae is enzootic, and in a far-removed comparison area having a disparate climate and lower density of vector ticks. Blood samples collected from both deer herds in 1987, 1988, and from 2000-02 were assayed for borrelial infection with microscopic and molecular methods. Serum specimens from two (5%) of 39 deer from the Dye Creek Preserve in Tehama County versus 13 (20%) of 64 animals from the Hopland Research and Extension Center (HREC) in Mendocino County, California were polymerase chain reaction (PCR) test positive for B. burgdorferi sensu lato. DNA sequencing analyses revealed that eight animals were infected with B. bissettii, six with three unclassified genotypes, and one with B. burgdorferi sensu stricto. One serum sample (2%) from HREC was positive for a relapsing-fever group spirochete that had a 16S rRNA sequence homology of 99% with the C053 type strain of B. coriaceae. Spirochetes undetermined to geno-species were detected in thick-blood drops prepared from three (8%) of 36 deer from the HREC by direct immunofluorescence. Adults of the hippoboscid flies Lipoptena depressa (n=73) and Neolipoptena ferrisi (n=24), the Pacific Coast tick (Dermacentor occidentalis) (n=22), and the western black-legged tick (Ixodes pacificus) (n=1) that had been removed from deer from both study areas in 2002 were PCR test negative for borreliae. The occurrence of diverse borreliae in deer from northern California confounds and, consequently, reduces the utility of borrelial serosurveys for detecting specific genospecies, unless they are complemented by more specific assays (e.g., immunoblotting, PCR/sequencing analysis).     

Correlation of Borrelia burgdorferi sensu lato prevalence in questing Ixodes ricinus ticks with specific abiotic traits in the western palearctic

This meta-analysis of reports examining ticks throughout the Western Palearctic region indicates a distinct geographic pattern for Borrelia burgdorferi sensu lato prevalence in questing nymphal Ixodes ricinus ticks. The greatest prevalence was reported between the 5°E and 25°E longitudes based on an analysis of 123 collection points with 37,940 nymphal tick specimens (87.43% of total nymphs; 56.35% of total ticks in the set of reports over the target area). Climatic traits, such as temperature and vegetation stress, and their seasonality correlated with Borrelia prevalence in questing ticks. The greatest prevalence was associated with mild winter, high summer, and low seasonal amplitude of temperatures within the range of the tick vector, higher vegetation indices in the May-June period, and well-connected vegetation patches below a threshold at which rates suddenly drop. Classification of the target territory using a qualitative risk index derived from the abiotic variables produced an indicator of the probability of finding infected ticks in the Western Palearctic region. No specific temporal trends were detected in the reported prevalence. The ranges of the different B. burgdorferi sensu lato genospecies showed a pattern of high biodiversity between 4°W and 20°E, partially overlapping the area of highest prevalence in ticks. Borrelia afzelii and Borrelia garinii are the dominant species in central Europe (east of ～25°E), but B. garinii may appear alone at southern latitudes and Borrelia lusitaniae is the main indicator species for meridional territories.