Serological reactivity to Borrelia burgdorferi sensu lato in dogs and horses from distinct areas in Romania

Lyme disease is a perfect model of the complex relationship between host, vector, and the vector-borne bacteria. Both dogs and horses in Romania are exposed to infection. The aim of the present study was to assess the seroreactivity against Borrelia burgdorferi sensu lato in dogs and horses from different regions of Romania. 276 samples from dogs and 260 samples from horses located in different regions of Romania were analyzed by ELISA and IFA, respectively. The effect of several factors potentially affecting seroreactivity (location, age, gender, occupation, and vector exposition risk) was evaluated using Fisher's exact test (R 2.12.0). The overall prevalence of anti-Borrelia antibodies was 6.52% (18/276) in dogs, with a significantly higher positivity (46.15%, 6/13, p = 0.0005) recorded in a midcountry region. Seroreactivity was correlated with occupation, with working dogs being more exposed. The results may indicate that Lyme borreliosis foci are restricted to small areas, but further studies on Borrelia prevalence in tick populations are needed to confirm this hypothesis. In horses, a global seroprevalence of 11.92% (31/260) was observed. No correlations were found between positive results and age, sex, county, or occupation. This is the first serological survey on antibodies to B. burgdorferi sensu lato in Romanian dogs and horses.     

Presence of Borrelia burgdorferi sensu lato in mites parasitizing small rodents

Ticks (especially those in the family Ixodidae) are the primary vectors of the infectious agent Borrelia burgdorferi sensu lato, which causes Lyme disease. To determine the potential role of mites as vectors of B. burgdorferi sensu lato, mites were collected from wild rodents in the Bazantula region of North Moravia (Czech Republic). These samples were examined for the presence of Borreliae by using DFM and PCR methods. Mites positive for the presence of DNA of B. burgdorferi sensu lato were determined as members of the families Haemogamasidae and Parasitidae. One sample from a mite of genus Haemogamasus was successfully isolated, and the specimen was confirmed as B. afzelii by using PCR-RFLP and by gradient SDS-PAGE. This suggests the possible participation of gamasid mites in borrelial circulation in nature and also points to the utility of further such studies to identify potential vectors (other than ticks) of the spirochete.     

Genetic diversity of Borrelia burgdorferi sensu lato isolates from Northeastern China

Thirty-two strains of Borrelia burgdorferi sensu lato were isolated from Ixodes persulcatus ticks collected from northeastern China from May to June in 2004 and 2005. Restriction fragment length polymorphism (RFLP) analysis and sequence analysis of 5S-23S rRNA intergenic spacer revealed that 29 (90.6%) belonged to Borrelia garinii, demonstrating B, C, and a unique pattern. The remaining three isolates (9.4%) were Borrelia afzelii with pattern D. The phylogenetic analysis based on 5S-23S rRNA intergenic spacer showed that B. garinii and B. afzelii genospecies clustered into two separate lineages. B. garinii strains were classified into three different branches: All the strains with RFLP pattern C were in the same branch, strain VH10 with a unique RFLP pattern clustered with strains VH9 and MDH2 with pattern B, and the rest of the strains with pattern B constitute another branch. These findings demonstrate the genetic diversity of B. burgdorferi sensu lato isolates from northeastern China.     

First isolation of Borrelia burgdorferi sensu lato from Ixodes ricinus ticks in Morocco

To determine the infection rate of Ixodes ricinus (I. ricinus) ticks with Borrelia burgdorferi sensu lato (B. burgdorferi sl) and to assess the frequency of the individual Borrelia species in this tick species, a total of 295 I. ricinus were collected in Taza region (Northeast of Morocco), from January to June 2002. The presence of B. burgdorferi sl was determined by direct fluorescence antibody assay (DFA) and by PCR after culture. B. burgdorferi sl isolates were identified at the species level by restriction fragment length polymorphism analysis of amplified products. The mean rate of I. ricinus infection with B. burgdorferi sl was 47.8%. Isolation attempts in BSK II medium resulted in 26 pure isolates. However, PCR performed on culture medium allowed to identify 82 Borrelia DNAs. B. lusitaniae has been identified from 76 out of 82 infected I. ricinus ticks (92.7%). Three ticks were infected by B. burgdorferi ss, and three other ticks were infected by B. garinii. This is the first report of the presence of B. burgdorferi sl in Morocco and more specifically of B. burgdorferi ss in North Africa.     

Prevalence and genetic heterogeneity of Borrelia burgdorferi sensu lato in Ixodes ticks in Belgium

Borrelia burgdorferi sensu lato is a genetically diverse group of spirochetes that includes the agent of Lyme borreliosis in which genospecies tend to be associated with specific clinical features. The aim of the study was to determine the prevalence and genetic diversity of Borrelia burgdorferi sensu lato in 524 ticks collected in woods of a western province of Belgium. Presence of spirochetes in ticks was determined by phase contrast microscopy. The mean infection rate of ticks was 12.0%. Variability was observed in the prevalence of infection among the five sites examined, ranging from 2.8 to 21.6%. Identification to genospecies was determined by PCR and sequencing. The most common genomospecies were Borrelia afzelii (55%) and Borrelia garinii (21%). For the first time in Belgium, we detected Borrelia valaisiana and Borrelia spielmanii, representing 14% and 2%, respectively. Borrelia burgdorferisensu stricto counted only for 2%. Co-infections were present in 8% of ticks. We emphasize the need for clinical studies to assess the prevalence of specific genospecies-related clinical manifestations of Lyme borreliosis in Belgium.     

Terrestrial distribution of the Lyme borreliosis agent Borrelia burgdorferi sensu lato in East Asia

Lyme borreliosis is the most prevalent tick-borne zoonosis and an important emerging infection in Europe, North America, and Far Eastern countries. The geographical distribution of Borrelia spp. and the relationship between Borrelia spp. and tick spp. in East Asian countries have been studied. In Northern Asian countries, Ixodes persulcatus carries Eurasian-type Borrelia garinii (20047 type), Borrelia afzelii, and Asian-type B. garinii (variant NT29), whereas Borrelia burgdorferi sensu stricto has not been isolated. In contrast, Asian-type B. garinii has not been found in the European vector tick Ixodes ricinus. These Borrelia spp. cause Lyme borreliosis in their respective countries. The specificity between Borrelia spp. and tick spp. has been confirmed from studies in the Moscow region, which is a sympatric region for the tick spp. I. persulcatus and I. ricinus. In Southeast Asian countries including the southernmost island of Okinawa, the Borrelia valaisiana-related genomic group is carried by Ixodes granulatus. In Japan, a similar borrelia strain Am501, is transmitted by Ixodes columnae. Ixodes ovatus transmits Borrelia japonica but not other species. On other hand, in central China and Nepal, the ticks harbor Borrelia sinica. It is believed that these molecular epidemiological surveys will provide useful information for the diagnoses and prevention of Lyme borreliosis in these countries.     

Prevalence of Borrelia burgdorferi sensu lato in Ixodes ricinus population in forests of north-western Poland

The ticks Ixodes ricinus were collected during three growing seasons in forested areas of north-western Poland. The ticks were collected by flagging at 30 sites. The specimens collected (nymphs and adults) were subjected, after an appropiate treatment, to indirect immunofluorescence analysis (IFA). In addition, effects of temperature and atmospheric precipitation on the tick infection with the spirochaete Borrelia burgdorferi were investigated based on data supplied by the Institute of Meteorology. A total of 8519 individuals of I. ricinus were collected at the sampling sites within May-October of three consecutive years. The pool of individuals obtained consisted of 7356 nymphs, 559 females, and 604 males. The B. burgdorferri prevalence varied rather widely, from 10 to 19%. Compared to nymphs, adult individuals showed a higher infection rate. A relationship between infection rate and I. ricinus activity in different years and months was studied in detail. The boreliosis risk was found to increase with increasing tick activity. On the other hand, no correlation was found between the meteorological parameters (temperature, precipitation), tick abundance, and the B. burgdorferi infection rate.     

Genetic diversity of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks collected in north-west Poland

Borrelia burgdorferi sensu lato (s. l.), the etiological agent of Lyme diesease, is transmitted by the bite of Ixodes ricinus. During May and September 1999, field surveys on Lyme disease spirochetes were conducted in three locations of a region of north-west Poland, known as recreational districts visited by many people. The ticks Ixodes ricinus were collected in natural habitats by dragging a flanel cloth over the vegetation. Sex and developmental stage of each tick were determined. Based on a polymerase chain reaction test with primers that recognize a chromosomal gene of all strains, out of the total 1414 specimens collected, 126 (8.9%) were found to be infected. The species B. burgdorferi s. l. comprises at least three pathogenic genomospecies, B. burgdorferi sensu stricto (s. s.), Borrelia garinii, and Borerelia afzelii, witch could be distinguished in nested-PCR tests with species-specific primers. B. burgdorferi s. s. was most prevalent (96% of infected ticks), followed by B. garinii (1.3%), and B. afzelii. was not found. Of the infected ticks, over the 99% were infected with a single species, one specimens was infected with two species. For 4 ticks, the infecting species could not be identied. The difference in rates of prevalence was observed among the tree locations (17%--5.3%--3.2%).     

中国莱姆病螺旋体菌株bmpA基因中人B细胞表位多态性分析

目的 研究我国伯氏疏螺旋体(Borrelia burgdorferi sensu lato),即莱姆病螺旋体菌株中bmpA基因及其人B细胞表位区的序列多态性。方法 选取61株莱姆病螺旋体分离株,PCR扩增其bmpA基因并测序后,结合4种基因型参考菌株序列,与从免疫表位数据库(Immune Epitope Database,IEDB)中查询到的B细胞表位序列进行比对分析。结果 中国B.garinii基因型菌株的cluster2、cluster3以及B.afzelii和B.valaisiana基因型所有菌株与参考序列比对后发现分别有3、9、5和18个异义突变。B细胞表位改变主要发生在B.afzelii基因型全部分离株和B.garinii基因型的cluster3及5株非成簇菌株。B.afzelii基因型菌株在B细胞表位区的异义突变A125S影响了2个B细胞表位;B.garinii基因型的cluster3和5株非成簇菌株B细胞表位区的3个异义突变导致5个B细胞表位均发生改变。结论 中国莱姆病螺旋体bmpA基因在4种基因型间和B.garinii基因型内存在较大多态性。     

我国部分地区蜱中莱姆病螺旋体的检测与基因分型研究

目的 对我国部分地区的多种蜱类进行莱姆病螺旋体的检测和基因分型。方法 选择我国黑龙江、吉林和浙江省部分林区为调查点，采集当地蜱类，用巢式PCR法进行检测，阳性产物进行限制性片段长度多态性（RFLP）分析和单链构象多态性（SSCP）分析，确定莱姆病螺旋体的基因型。结果 共检测蜱512只，阳性126只，阳性率24．61％。其中吉林全沟硬蜱带菌率为37．00％，黑龙江全沟硬蜱带菌率为20．87％，浙江长角血蜱带菌率为28．07％。RFLP分析表明，蜱中莱姆病螺旋体包括B．garinii和B．afzelii两种基因型。SSCP分析显示为7种亚型，其中B．garinii分为5个亚型，B．afzelii分为2个亚型。发现有3只蜱同时感染不同基因（亚）型莱姆病螺旋体。结论 证实B．garinii和B．afzelii基因型为我国莱姆病螺旋体的优势基因型，并在我国蜱中发现莱姆病螺旋体不同基因（亚）型的混合感染。     

Development of real-time polymerase chain reaction for detection of Borrelia burgdorferi sensu lato in China

Universal primers and probes were selected on the basis of the 16S rRNA gene sequence of Borrelia burgdorferi in GenBank?, and a real-time polymerase chain reaction (PCR) method for detection of B. burgdorferi was established. The results showed that this method could specifically detect the B31 strain (Borrelia burgdorferi sensu stricto), the BO23 strain (Borrelia afzelii), and the SZ strain (Borrelia garinii), without cross-reaction with genome DNA of Theileria (T. luwenshuni, T. uilenbergi, T. sinensis, T. annulata, T. sergenti, T. annulata), Babesia (B. bigemina, B. ovate, B. sp. (Xinjiang)), Anaplasma (A. marginale, A. ovis), Mycoplasma mycoides subsp. capri, and Chlamydia psittaci, which are the infective pathogens to yak and/or sheep. The sensitivity of this real-time PCR is 10? times greater than that of a conventional PCR. The real-time PCR was able to amplify 16S rRNA gene from as few as 22.88 fg genomic DNA of B. burgdorferi sensu lato. Tick DNAs from 369 field samples collected from Shangzhi City of Heilongjiang Province were tested, resulting in an infection rate of 42.80%, and a total of 332 genomic DNAs from the blood of 186 yaks and 146 sheep in the Gannan Tibetan Autonomous Prefecture of Gansu Province were tested, resulting in 24.19% positive rate for the yaks and 39.04% positive rate for the sheep.     

Molecular and serological evidence of Borrelia burgdorferi sensu lato in wild rodents in the Czech Republic

The aim of the present study was to determine the frequency and spatial distribution of the Borrelia species in wild rodents in the Czech Republic. In total, 293 muscle tissue samples and 106 sera from 293 wild rodents captured in North Bohemia and North-East and South Moravia were examined for the presence of Borrelia spp. and antibodies. Muscle samples were investigated with real-time polymerase chain reaction (PCR) with a recA primer set, with DNA quantification and melting curve analysis, and with restriction fragment length polymorphism (RFLP) analysis of the 5S-23S rDNA intergenic spacer. Infection with Borrelia burgdorferi sensu lato was found in 16.4% of the muscle samples. The most abundant genospecies was Borrelia afzelii (11.3%), followed by Borrelia burgdorferi sensu stricto (4.8%) and Borrelia garinii (0.7%). Borrelia infection was more frequently observed in Clethrionomys glareolus than in Apodemus spp. Sera were analyzed with an enzyme-linked immunosorbent assay (ELISA) test, yielding the total seropositivity rates of 24.5% for anti-Borrelia IgM antibodies and 25.5% for IgG antibodies. Total seroprevalence was higher in Apodemus spp. than in C. glareolus. In conclusion, our data indicate that in the Czech Republic small wild rodents can serve as hosts for B. burgdorferi s. s. as well as for B. afzelii.     

Lyme borreliosis incidence in two French departments: correlation with infection of Ixodes ricinus ticks by Borrelia burgdorferi sensu lato

We conducted a prospective study to estimate the Lyme borreliosis incidence in two rural French departments, Meuse and Puy-de-D?me. Concurrently, we investigated the prevalence of ticks infected with Borrelia burgdorferi sensu lato (sl) and Anaplasma phagocytophilum. The incidence of Lyme borreliosis decreased from 156 to 109/100,000 inhabitants in Meuse and from 117 to 76/100,000 inhabitants in Puy-de-D?me in 2004 and 2005, respectively, corresponding to a decrease in the density of Ixodes ricinus nymphs infected with B. burgdorferi sl. During the same period, the density of adult ticks increased. Interestingly, B. valaisiana, a nonpathogenic species, infected adult ticks more often than nymphs. These results confirmed the correlation between the Lyme borreliosis incidence and the density of infected nymphs, a stage preferentially infected with B. afzelii. In contrast, we found a low rate of infection by A. phagocytophilum, ranging from 0% to 0.4% in Puy-de-D?me and from 0.8% to 1.4% in Meuse, suggesting a low risk for humans.     

Significance of red deer (Cervus elaphus) in the ecology of Borrelia burgdorferi sensu lato

BACKGROUND: Red deer (Cervus elaphus) is one of the most important host of the adult tick (Ixodes ricinus) which is the basic vector of the Lyme disease causative agent--Borrelia burgdorferi sensu lato in Europe. The aim of the present study was to establish the role of red deer in the transmission of B. burgdorferi s.1. Material and methods. Tissues from 74 red deers were evaluated and the presence of B. burgdorferi s.1 DNA was identified using nested PCR technique based on fla gene. The identification of species belonging to B. burgdorferi s.1 complex was performed after restriction digestion of nested PCR product with Ddel enzyme and sequencing of nested PCR product. The study included also 55 isolates of I. ricinus females removed from red deer and 466 ticks (73 adult and 393 nymphs) collected from the vegetation in the area where the red deer lives. RESULTS: There were no DNA of B. burgdorferi s.1 complex in the red deer tissues and in ticks removed from deer, however in one tick removed from deer the DNA of other Borrelia species--B. miyamotoi was identified. In ticks collected from vegetation 3 species belonging to B. burgdorferi s.1. complex were identified: B. garinii (3.2% ticks studied), B. afzelii (6.9%) and B. valaisiana (3.6%), however DNA of B. miyamotoi was absent. These results confirm inability of survival of B. burgdorferi s.1. species in tick I. ricinus feeding on red deer blood. However there is a possibility of survival of B. miyamotoi in presence of deer blood at least in ticks feeding on red deer. The main role of red deer in keeping the constant infection level of B. burgdorferi s.1. in the whole population of I. ricinus ticks does not concern B. miyamotoi.     

Indication of Borrelia burgdorferi sensu lato in the taiga tick larvae obtained from spontaneously infected females

Hungry larvae from 17 clutches by spontaneously infected Ixodes persulcatus females were examined by inoculation of the BSK II medium, by microscopy of fixed smears, and by polymerase chain reaction (PCR) with the primers specific toward the conserved sequences of Borrelia burgdorferi 16S ribosomal RNA gene. A study of 781 larvae individually or as pools could not reveal Borrelia DNA by PCR. Inoculations of the BSK II medium with 600 larvae yielded no positive results either; immobile spiral forms of Bacillus spp. were detected in 16 (26.7 +/- 5.7%) cultures of the larvae obtained from 7 females. Microscopy of 1416 fixed smears showed typical Borrelia in 7 (0.5 +/- 0.4%) specimens of larvae resulting from the same hatch; spirochaete-like cells were present in 13 (0.9 +/- 0.5%) cases. The single female from those of the 17 hatches transmitted Borrelia through eggs to filial-generation larvae. The infection rate of the larvae emerged from the eggs of this hatch was 7% and their individual infection rates were 0.4-0.8 Borrelia per 100 fields of vision. The findings suggest that there may a transovarian transmission of Borrelia in I. persulcatus ticks, but its likelihood is very little.     

Serologic survey of the wild boar (Sus scrofa) for Borrelia burgdorferi sensu lato

Sera of 642 wild boars (Sus scrofa) shot by hunters in ten administrative regions of the Czech Republic during 1995-2000, were tested by indirect hemagglutination assay (IHA) for the presence of anti-Borrelia IgG. Antibodies to Borrelia burgdorferi sensu lato (Bb) were detected in serum samples from all 10 regions, and overall seroprevalence rate was 12.8%. Titres of antibodies ranged from 1:80 to 1:640. Borrelia antibodies were most frequent in the animals from three administrative regions of the Czech Republic: Moravskoslezsky (25.0%), Pardubicky (25.0%) and Královehradecky (24.1%), followed by the regions Plzen sky (16.7%), Olomoucky (13.3%), Jihomoravsky (12.8%), Vysoc ina (11.1%), Jihoc esky (11.1%), Zlínsky (10.3%), and Liberecky (8.9%). Seasonal seroprevalence rate increased in March and April, the peak was in May. The results suggest frequent exposure of wild boars to ixodid ticks infected with Bb, predominantly in rural and forested regions. The study also reviews the importance of wild boar in Lyme borreliosis (LB) ecology. Wild boar serology may provide another means of surveillance of endemic areas of LB.     

Sero-prevalence of granulocytic Ehrlichia spp. and Borrelia burgdorferi sensu lato in Swedish dogs 1991-94

In Sweden, 2 tick-borne zoonotic diseases, granulocytic ehrlichiosis and borreliosis, are frequently diagnosed in dogs, using serological assays. The aims of this study were to determine the sero-prevalences of antibodies to Ehrlichia spp. and Borrelia burgdorferi sensu lato during 1991-94 in dogs, not clinically suspected to be infected with either of the 2 agents. Samples (n = 611) were selected from a serum bank using a systematic sampling strategy, stratified across the 4-y period. The stored sera had originally been submitted in order to verify or rule out infection with Sarcoptes scabiei. The overall sero-prevalence for Ehrlichia spp. was 17.7% and for Borrelia burgdorferi sensu lato 3.9% (n = 588). Only a few dogs in the northern part of Sweden were sero-positive for Ehrlichia spp. and none were positive for Borrelia burgdorferi sensu lato. An increased sero-prevalence of Ehrlichia spp. was seen during the years studied. The sero-prevalence of Ehrlichia spp. varied with season. Sero-positivity to both agents increased with age. Both diseases are considered zoonotic, and the increase in sero-prevalence of Ehrlichia spp. over the years may reflect the degree of infection in ticks and may have implications for human health.     

Occurence of pathogenic genospecies of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks collected from north-western Poland

In order to learn the heterogeneity of the DNA of B. burgdorferi s.l. and the prevalence of co-infections of B. burgdorferi s.l. genospecies in the populations of I. ricinus, collected in north-western Poland, the nested PCR method was applied, a fragment of the fla gene being used as a marker. Basing on the prevalence data of B. burgdorferi s.l. DNA in I. ricinus ticks in 8 sampling sites during 1998-2001, it may be stated that a risk of contracting Lyme disease exists in forested areas of north-western Poland, the highest in relation to B. burgdorferi s.s. (76.3% infected ticks), lower by B. garinii (2% infected ticks), and minimal threat being posed by B. afzelii (0.3%). I. ricinus ticks collected in north-western Poland pose a risk of contracting double infection by B. burgdorferi s.l. genospecies, i.e. B. burgdorferi s.s. with B. garinii, and B. burgdorferi s.s. with B. afzelii. The north-western part of Poland represents an endemic area for B. burgdorferi s.l.