Detection and molecular typing of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks and in different patient samples from southwest Germany

Estimated number of symptomatic Lyme borreliosis cases in Germany in 2021 after adjusting for under-ascertainment

BACKGROUND

Although nine of 16 federal states in Germany conduct public health surveillance for Lyme borreliosis (LB), the extent of under-ascertainment is unknown.

OBJECTIVE

As a model for European countries that conduct LB surveillance, we sought to estimate the population-based incidence of symptomatic LB after adjusting for under-ascertainment.

METHODS

Estimating seroprevalence-derived under-ascertainment relies on data from seroprevalence studies, public health surveillance, and published literature. The number of symptomatic LB cases in states that conduct LB surveillance was estimated from studies reporting the seroprevalence of antibodies against Borrelia burgdorferi sensu lato, the proportion of LB cases that are asymptomatic, and the duration of antibody detection. The number of estimated incident symptomatic LB cases was compared with the number of surveillance-reported LB cases to derive under-ascertainment multipliers. The multipliers were applied to the number of 2021 surveillance-reported LB cases to estimate the population-based incidence of symptomatic LB in Germany.

RESULTS

Adjusting for seroprevalence-based under-ascertainment multipliers, the estimated number of symptomatic LB cases in states that conducted surveillance was 129,870 (408 per 100,000 population) in 2021. As there were 11,051 surveillance-reported cases in 2021 in these states, these data indicate there were 12 symptomatic LB cases for every surveillance-reported LB case.

CONCLUSIONS

We demonstrate that symptomatic LB is underdetected in Germany and that this seroprevalence-based approach can be applied elsewhere in Europe where requisite data are available. Nationwide expansion of LB surveillance would further elucidate the true LB disease burden in Germany and could support targeted disease prevention efforts to address the high LB disease burden.

Cutaneous Lyme borreliosis: Guideline of the German Dermatology Society

This guideline of the German Dermatology Society primarily focuses on the diagnosis and treatment of cutaneous manifestations of Lyme borreliosis. It has received consensus from 22 German medical societies and 2 German patient organisations. It is the first part of an AWMF (Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften e.V.) interdisciplinary guideline: “Lyme Borreliosis – Diagnosis and Treatment, development stage S3”.

The guideline is directed at physicians in private practices and clinics who treat Lyme borreliosis. Objectives of this guideline are recommendations for confirming a clinical diagnosis, recommendations for a stage-related laboratory diagnosis (serological detection of IgM and IgG Borrelia antibodies using the 2-tiered ELISA/immunoblot process, sensible use of molecular diagnostic and culture procedures) and recommendations for the treatment of the localised, early-stage infection (erythema migrans, erythema chronicum migrans, and borrelial lymphocytoma), the disseminated early-stage infection (multiple erythemata migrantia, flu-like symptoms) and treatment of the late-stage infection (acrodermatitis chronica atrophicans with and without neurological manifestations). In addition, an information sheet for patients containing recommendations for the prevention of Lyme borreliosis is attached to the guideline.

Progress in the molecular diagnosis of Lyme disease

INTRODUCTION

Current laboratory testing of Lyme borreliosis mostly relies on serological methods with known limitations. Diagnostic modalities enabling direct detection of pathogen at the onset of the clinical signs could overcome some of the limitations. Molecular methods detecting borrelial DNA seem to be the ideal solution, although there are some aspects that need to be considered. Areas covered: This review represent summary and discussion of the published data obtained from literature searches from PubMed and The National Library of Medicine (USA) together with our own experience on molecular diagnosis of Lyme disease. Expert commentary: Molecular methods are promising and currently serve as supporting diagnostic testing in Lyme borreliosis. Since the field of molecular diagnostics is under rapid development, molecular testing could become an important diagnostic modality.

Broad-range survey of tick-borne pathogens in Southern Germany reveals a high prevalence of Babesia microti and a diversity of other tick-borne pathogens

Abstract Ticks harbor numerous pathogens of significance to human and animal health. A better understanding of the pathogens carried by ticks in a given geographic area can alert health care providers of specific health risks leading to better diagnosis and treatments. In this study, we tested 226 Ixodes ricinis ticks from Southern Germany using a broad-range PCR and electrospray ionization mass spectrometry assay (PCR/ESI-MS) designed to identify tick-borne bacterial and protozoan pathogens in a single test. We found 21.2% of the ticks tested carried Borrelia burgdorferi sensu lato consisting of diverse genospecies; a surprisingly high percentage of ticks were infected with Babesia microti (3.5%). Other organisms found included Borrelia miyamotoi, Rickettsia helvetica, Rickettsia monacensis, and Anaplasma phagocytophilum. Of further significance was our finding that more than 7% of ticks were infected with more than one pathogen or putative pathogen.

Geodemographic analysis of Borrelia burgdorferi sensu lato using the 5S-23S rDNA spacer region

BACKGROUND

Lyme borreliosis is the predominant tick-borne disease in the Northern hemisphere, with considerable heterogeneity in clinical manifestations. Here, we evaluated one genetic marker for its use in population genetic based analysis. For that we collected molecular and epidemiological records of Borrelia burgdorferi sensu lato isolates from ticks, animals and humans at various sites in The Netherlands and worldwide.

METHODS

The 5S-23S rDNA (rrfA-rrlB) intergenic spacer region (IGS) from 291 Dutch Borrelia positive ticks was sequenced and compared to Borrelia sequences from GenBank. We estimated several population genetic measures to test the neutrality of the marker. We also assessed the ability of this marker to discriminate between Eurasian Borrelieae at a finer geographical resolution, and to detect population expansion per genospecies.

RESULTS

The most prevalent genospecies in The Netherlands was Borrelia afzelii, whereas Borrelia garinii, B. burgdorferi sensu stricto, Borrelia spielmanii and Borrelia valaisiana were found less frequently. The result of the Ewens-Watterson-Slatkin test was consistent with neutral selection of IGS region. Estimated pairwise fixation indices (Fst) were significantly different from zero between The Netherlands, the rest of Europe, Russia and Asia for B. afzelii and Borrelia garinii. Estimated Fu's Fs were significantly negative for B. afzelii and B. garinii.

CONCLUSIONS

At least seven B. burgdorferi s.l. genospecies circulate in Ixodes ricinus population in The Netherlands. The population genetic analyses of IGS region can resolve subpopulations within a genospecies and detect a large excess of rare genetic variants at the genospecies level. A genetic trace of population expansion for B. afzelii and B. garinii is consistent with the reported increase in Lyme borreliosis incidence in European countries.

Prevalences of tick-borne encephalitis virus and Borrelia burgdorferi sensu lato in Ixodes ricinus populations of the Rhine-Main region, Germany

Tick-borne encephalitis (TBE) and Lyme borreliosis are the most common tick-borne zooanthroponoses in Germany. The federal risk map for TBE in this country is based on recorded cases of human infection, whereas information on the vector-based prevalence of either pathogen is fragmentary. In this study, a total of 12,497 host-seeking nymphal and adult Ixodes ricinus ticks (Acari: Ixodidae) were collected from March to October 2009 and April to June 2010, in 5 TBE non-risk and 4 TBE risk areas of the Rhine-Main region (Hesse) via flagging. A total of 3615 ticks was examined for infection with Borrelia burgdorferi sensu lato and 9115 ticks were analyzed for TBE virus (TBEV). Pathogens were detected by real-time polymerase chain reaction. Among 3615 questing ticks, 344 (9.5%) were found infected with B. burgdorferi sensu lato. Five Borrelia genospecies were identified by sequencing the OspA gene: B. afzelii (81.3%), B. garinii (14.0%), B. valaisiana (2.7%), B. spielmanii (1.3%), and B. bavariensis (0.7%). TBE infection of ticks differed between areas classified as TBE risk and TBE non-risk areas. While the prevalence of TBEV was between 0 and 0.2% (3 of 3947 ticks) in the TBE risk areas, no TBEV-infected tick was detected from TBE non-risk areas. The results show that B. burgdorferi sensu lato occurred in all 9 examined locations, indicating that Lyme borreliosis is prevalent in the Rhine-Main region, whereas TBEV was detected only in previously classified risk areas.

Ability to cause erythema migrans differs between Borrelia burgdorferi sensu lato isolates

Background

Lyme borreliosis is a tick-borne disease caused by Borrelia burgdorferi sensu lato. The variety of characteristic and non-specific clinical manifestations is partially explained by its genetic diversity. We investigated the ability of B. burgdorferi sl isolates to cause erythema migrans.

Methods

The genetic constellation of isolates from ticks was compared to isolates found in erythema migrans. PCR and sequence analysis was performed on the plasmid-encoded ospC and the chromosomal 5S-23S rDNA spacer region (IGS).

Results

Seven different B. burgdorferi sl genospecies were identified in 152 borrelia isolates from ticks and erythema migrans biopsies. B afzelii (51%) and B. garinii (27%) were the most common in ticks. From the 44 sequences obtained from erythema migrans samples 42 were B. afzelii, one B. garinii and one B. bavariensis. Significant associations with erythema migrans formation were found for four IGS and two ospC types. Five from 45 ospC types were associated with more than one genospecies.

Conclusions

B. burgdorferi sl isolates differ in their propensity to cause erythema migrans. These differences were also found within genospecies. In other words, although B. afzelii was mostly associated with erythema migrans, some B. afzelii isolates had a low ability to cause erythema migrans. Our data further support the occurrence of plasmid exchange between borrelia genospecies under natural conditions.

Detection and differentiation of Borrelia burgdorferi sensu lato in ticks collected from sheep and cattle in China

BACKGROUND

Lyme disease caused by Borrelia burgdorferi sensu lato complex is an important endemic zoonosis whose distribution is closely related to the main ixodid tick vectors. In China, isolated cases of Lyme disease infection of humans have been reported in 29 provinces. Ticks, especially ixodid ticks are abundant and a wide arrange of Borrelia natural reservoirs are present. In this study, we developed a reverse line blot (RLB) to identify Borrelia spp. in ticks collected from sheep and cattle in 7 Provinces covering the main extensive livestock regions in China.

RESULTS

Four species-specific RLB oligonucleotide probes were deduced from the spacer region between the 5S-23S rRNA gene, along with an oligonucleotide probe which was common to all. The species specific probes were shown to discriminate between four genomic groups of B. burgdorferi sensu lato i.e. B. burgdorferi sensu stricto, B. garinii, B. afzelii, and B. valaisiana, and to bind only to their respective target sequences, with no cross reaction to non target DNA. Furthermore, the RLB could detect between 0.1 pg and 1 pg of Borrelia DNA.A total of 723 tick samples (Haemaphysalis, Boophilus, Rhipicephalus and Dermacentor) from sheep and cattle were examined with RLB, and a subset of 667 corresponding samples were examined with PCR as a comparison. The overall infection rate detected with RLB was higher than that of the PCR test.The infection rate of B. burgdoreri sensu stricto was 40% in south areas; while the B. garinii infection rate was 40% in north areas. The highest detection rates of B. afzelii and B. valaisiana were 28% and 22%, respectively. Mixed infections were also found in 7% of the ticks analyzed, mainly in the North. The proportion of B. garinii genotype in ticks was overall highest at 34% in the whole investigation area.

CONCLUSION

In this study, the RLB assay was used to detect B. burgdorferi sensu lato in ticks collected from sheep and cattle in China. The results showed that B. burdorferi senso stricto and B. afzelii were mainly distributed in the South; while B. garinii and B. valaisiana were dominant in the North. Borrelia spirochaetes were detected in Rhipicephalus spp for the first time. It is suggested that the Rhipicephalus spps might play a role in transmitting Borrelia spirochaetes.

Are birds reservoir hosts for Borrelia afzelii?

It is known that birds are competent reservoir hosts of particular Borrelia species like B. garinii and B. valaisiana but not for B. afzelii, a rodent-associated genospecies. Since they can carry infected ticks over long distances, they are also important covectors for Lyme borreliosis spirochaetes. To assess the role of different bird species in transmission and dispersal of Borrelia OspA types, we examined 191 Ixodes ricinus ticks from 99 birds, captured on a German conservation island in the Baltic Sea in spring 2007. Surprisingly, more than one third of the 27 positive samples were identified as B. afzelii. The cause for this unusually high prevalence remains unknown, indicating the need of further studies on bird-feeding ticks that should include a higher sample size.

Lyme borreliosis--an update

Lyme borreliosis is the most common tick-borne, infectious disease in the northern hemisphere. Disease manifestations in the United States and Europe vary as a result of geographic distribution of different species within the genospecies Borrelia burgdorferi sensu lato, which in turn are host-specific. Certain toxigenic B. burgdorferi strains cause early disseminated disease. The ability of Borrelial organisms to break down the extracellular matrix also promotes dissemination. B. burgdorferi are eliminated by complement-mediated lysis and by T and B cell activity of the specific immune response. Yet, B. burgdorferi can evade humoral immunity by means of type of protective mechanism by which it adheres to the proteoglycan decorin in the joints and skin. A further factor in the persistence of the pathogen is altered antigen expression. Re-infection usually occurs with a different strain, although repeated infection with the same strain is also possible after a certain period of latency. New developments in serologic testing include the use of recombinant native antigen as well as antigens produced in vivo such as VlsE (variable major protein-like sequence, expressed) or decorin-binding protein A. Diagnosis continues to be complicated by seropositivity of healthy individuals, the persistence of antibodies after therapy, and a lacking humoral immune response in patients with erythema migrans.

Pathogens and host DNA in Ixodes ricinus nymphal ticks from a German forest

Unfed nymphs of Ixodes ricinus were collected from vegetation in a forest on the outskirts of Berlin, Germany and were analyzed for host and pathogen DNA. Pathogens were detected in 47% of the ticks. Borrelia afzelii was the commonest pathogen detected, followed by Rickettsia helvetica. Other pathogens included B. valaisiana, B. garinii, B. burgdorferi sensu stricto, Anaplasma phagocytophilum, and a relapsing fever-like Borrelia. Most of the host DNA detected was of rodent origin and was associated with infection by B. afzelii, R. helvetica, and A. phagocytophilum. Bird DNA was associated with B. valaisiana and B. garinii, and ruminant DNA with A. phagocytophilum. B. afzelii was also found in two ticks that contained bird DNA.

Evaluation of an internally controlled real-time PCR targeting the ospA gene for detection of Borrelia burgdorferi sensu lato DNA in cerebrospinal fluid

This study reports the development and evaluation of an internally controlled real-time PCR targeting the ospA gene for detection of Borrelia burgdorferi sensu stricto, Borrelia garinii, Borrelia afzelii and Borrelia valaisiana. DNA was extracted using QIAamp DNA Blood Mini kit columns. DNA from 33 B. burgdorferi sensu lato strains reacted in the assay, whereas no reactivity was observed with DNA from four relapsing fever Borrelia spp., 11 unrelated spirochaetes, and 31 unrelated microorganisms. The quantitative sensitivity of the assay was 1-10 fg of Borrelia DNA and one to five cultured Borrelia spirochaetes. Cerebrospinal fluid (CSF) specimens from 70 patients sent for routine testing for neuroborreliosis, and three CSF specimens containing B. garinii were also tested. Positive PCR results were obtained with all three culture-confirmed neuroborreliosis specimens, five of ten neuroborreliosis specimens with specific antibodies in CSF and pleocytosis, none of nine specimens from possible cases of early neuroborreliosis (antibodies in serum, CSF pleocytosis, no antibodies in CSF), one of 15 specimens from patients with active or past Lyme disease with neurological signs (antibodies in serum, no pleocytosis or antibodies in CSF), and none of 36 specimens from patients without Lyme borreliosis (no antibodies in serum or CSF). Overall, the real-time PCR assay enabled sensitive and specific detection of all B. burgdorferi sensu lato species tested. The PCR had a sensitivity of 50% in patients with neuroborreliosis. The main diagnostic role of the assay could be to confirm neuroborreliosis in patients for whom the diagnosis is doubtful.

Epidemiology of Tick Bites and Borreliosis in Children Attending Kindergarten or So-Called “Forest Kindergarten” in Southwest Germany

The so-called "forest kindergartens" have been increasingly popular in Germany since the beginning of the 1990s. These are nurseries located in forested areas where children spend all-season full-time outdoors. Fifty-three kindergartens in the state of Baden-Württemberg, Germany participated in this study. In a prospective clinical cohort study, the child's personal data, history, protective parental habits concerning tick bites, number of tick bites, and cases of borreliosis were recorded monthly (March-October 2004) using a questionnaire. Altogether, 1,707 children of 25 "forest kindergartens" (506 children) and 28 conventional kindergartens (1,201 children) were included. The response rate was 75% in "forest kindergartens" and 65% in conventional kindergartens. In the "forest kindergartens", 1,503 tick bites especially on the trunk and on the head were found, whereas 502 tick bites were registered in conventional kindergartens. Sixteen cases of borreliosis were diagnosed (10 in "forest kindergartens", six in conventional kindergarten), most frequently manifesting as erythema migrans. Children attending a "forest kindergarten" have a 2.8 times increased risk of experiencing tick bites and a 4.6 times increased risk of suffering from borreliosis compared to conventional kindergarten in Germany, although protective parental behavior in "forest kindergarten" children was significantly better than that in conventional kindergarten.

Borrelia burgdorferi infection prevalences in questing Ixodes ricinus ticks (Acari: Ixodidae) in urban and suburban Bonn, western Germany

From March to October 2003, a total of 2,518 host-seeking Ixodes ricinus ticks (1,944 nymphs, 264 females, 310 males) were collected by blanket dragging at 45 sites all over the city area of Bonn, western Germany, to be checked for Borrelia burgdorferi infection. The collection sites included 20 private gardens, nine public recreational parks, the boundaries of 14 sylvatic suburban areas and two footpaths between suburban farmed fields. Generally, numbers of specimens collected along sylvatic suburban areas and at urban sites with dense tree populations were significantly higher than at the other collection sites. Out of 1,394 specimens (865 nymphs, 241 females, 288 males) that were randomly chosen for Borrelia analysis by a simple PCR, 250 (17.9 %) were found to be infected with B. burgdorferi sensu lato. While the infection prevalences varied significantly between females (26.6%), males (12.5%) and nymphs (17.3%), there were no striking differences between sylvatic and unwooded sites. A total of 92.8% of the ticks Borrelia-positive by the simple PCR were also positive in a diagnostic nested PCR. Using genospecies-specific oligonucleotide probes, single Borrelia genospecies infections (91.4%) could be assigned to B. afzelii (39.5%), B. garinii (27.9%), B. burgdorferi sensu stricto (15.6%) and B. valaisiana (8.6%) by DNA hybridization. Various combinations of double infections were observed in 4.3% of the infected ticks. Another 4.3% of the Borrelia infections were untypeable. The B. burgdorferi genospecies distribution in the city area was shown to be variable from site to site and, even more, it was distinct from rural collection sites near Bonn. This is ascribed to a different spectrum of reservoir hosts. Taking into account the infection prevalences of host-seeking ticks in the forested surroundings of Bonn, our study demonstrates that the risk of acquiring Lyme disease after a tick bite in urban/suburban areas is comparably as high as in woodlands outside of the city.