Elevated levels of serum muscle enzymes in the initial phase of tick-borne encephalitis.

PURPOSE: Since some patients with tick-borne encephalitis (TBE) have pronounced myalgias, and since myositis is reported in Flavivirus diseases such as dengue, we performed systematic search for abnormalities of muscle enzymes in a group of patients in whom the presence of tick-borne encephalitis virus (TBEV) RNA in the first phase of the disease was demonstrated and who developed second phase of TBE. METHODS: Total leukocyte and platelet blood counts were determined routinely at the initial examination during the first and the second phase of TBE. Activity of aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CK), myoglobin and troponin was determined from the available stored serum specimens; the first and second phase disease specimens were tested simultaneously. RESULTS: Of 24 patients with biphasic course of TBE, 83% had leukopenia, 65% thrombocytopenia, 83% elevated AST and 4% elevated ALT level. Furthermore, 33% had elevated serum CK, 26% myoglobin and 22% troponin activity; at least one of the muscle enzymes was elevated in 42% of patients. Leukopenia, thrombocytopenia, elevated liver enzymes and elevations of CK and myoglobin were present in the initial phase but resolve later, while troponin abnormalities were also found in the second phase of TBE. CONCLUSIONS: The present study exposes that in addition to previously known leukopenia, thrombocytopenia and increased liver enzymes activity, the initial phase of TBE is relatively often associated also with elevated muscle enzymes. Clinical relevance of these findings remains to be determined.

Why Is the Duration of Erythema Migrans at Diagnosis Longer in Patients with Lyme Neuroborreliosis Than in Those without Neurologic Involvement?

In prior studies, the skin lesion erythema migrans (EM) was present for a longer time period before diagnosis of concomitant borrelial meningoradiculoneuritis (Bannwarth's syndrome) compared to EM patients without neurologic symptoms. To determine if this observation pertains to other manifestations of Lyme neuroborreliosis (LNB), we compared EM characteristics in patients with borrelial meningoradiculoneuritis (n = 122) to those with aseptic meningitis without radicular pain (n = 72 patients), and to patients with EM but without neurologic involvement (n = 12,384). We also assessed factors that might impact duration. We found that the duration of EM at diagnosis in patients with borrelial meningoradiculoneuritis was not significantly different compared with those with LNB without radicular pain (34 vs. 26 days; p = 0.227). The duration of EM for each of these clinical presentations of LNB, however, was significantly longer than in patients with EM without LNB (10 days; p < 0.001). Contributing factors to this difference might have been that patients with LNB failed to recognize that they had EM or were unaware of the importance of not delaying antibiotic treatment for EM. In conclusion, the duration of the EM skin lesion in EM patients with LNB is longer than in patients with just EM, irrespective of the type of LNB.

Microbiologic Findings in a Cohort of Patients with Erythema Migrans.

Erythema migrans (EM) is the initial and the most frequent clinical manifestation of Lyme borreliosis (LB). Herein, we report on the capacity of culture and serology for the demonstration of Borrelia infection in a cohort of 292 patients diagnosed with typical EM at a single medical center. The median duration of EM at diagnosis was 12 days, and the largest diameter was 16 cm; 252 (86.3%) patients presented with solitary EM, whereas 40 (13.7%) had multiple EM. A total of 95/292 (32.5%) patients had positive IgM, and 169 (57.9%) had positive IgG serum antibodies; the Borrelia isolation rate was 182/292 (62.3%). The most frequent species by far was B. afzelii (142/148, 95.9%) while B. garinii (2.7%) and B. burgdorferi s.s. (1.4%) were rare. IgM seropositivity was associated with a younger age, multiple EM and the absence of underlying chronic illness; IgG seropositivity was associated with the duration of EM at diagnosis, the diameter of the EM, having had a previous episode of LB and the absence of symptoms at the site of the EM. Furthermore, the Borrelia isolation rate was statistically significantly lower in patients with positive Borrelia IgM antibodies. Although microbiologic analyses are not needed for the diagnosis of typical EM, they enable insights into the etiology and dynamics of the immune response in the course of early LB.

COVID-19 and cholesterol biosynthesis: Towards innovative decision support systems.

With COVID-19 becoming endemic, there is a continuing need to find biomarkers characterizing the disease and aiding in patient stratification. We studied the relation between COVID-19 and cholesterol biosynthesis by comparing 10 intermediates of cholesterol biosynthesis during the hospitalization of 164 patients (admission, disease deterioration, discharge) admitted to the University Medical Center of Ljubljana. The concentrations of zymosterol, 24-dehydrolathosterol, desmosterol, and zymostenol were significantly altered in COVID-19 patients. We further developed a predictive model for disease severity based on clinical parameters alone and their combination with a subset of sterols. Our machine learning models applying 8 clinical parameters predicted disease severity with excellent accuracy (AUC = 0.96), showing substantial improvement over current clinical risk scores. After including sterols, model performance remained better than COVID-GRAM. This is the first study to examine cholesterol biosynthesis during COVID-19 and shows that a subset of cholesterol-related sterols is associated with the severity of COVID-19.

Whole genome sequencing of human Borrelia burgdorferi isolates reveals linked blocks of accessory genome elements located on plasmids and associated with human dissemination.

Lyme disease is the most common vector-borne disease in North America and Europe. The clinical manifestations of Lyme disease vary based on the genospecies of the infecting Borrelia burgdorferi spirochete, but the microbial genetic elements underlying these associations are not known. Here, we report the whole genome sequence (WGS) and analysis of 299 B. burgdorferi (Bb) isolates derived from patients in the Eastern and Midwestern US and Central Europe. We develop a WGS-based classification of Bb isolates, confirm and extend the findings of previous single- and multi-locus typing systems, define the plasmid profiles of human-infectious Bb isolates, annotate the core and strain-variable surface lipoproteome, and identify loci associated with disseminated infection. A core genome consisting of ~900 open reading frames and a core set of plasmids consisting of lp17, lp25, lp36, lp28-3, lp28-4, lp54, and cp26 are found in nearly all isolates. Strain-variable (accessory) plasmids and genes correlate strongly with phylogeny. Using genetic association study methods, we identify an accessory genome signature associated with dissemination in humans and define the individual plasmids and genes that make up this signature. Strains within the RST1/WGS A subgroup, particularly a subset marked by the OspC type A genotype, have increased rates of dissemination in humans. OspC type A strains possess a unique set of strongly linked genetic elements including the presence of lp56 and lp28-1 plasmids and a cluster of genes that may contribute to their enhanced virulence compared to other genotypes. These features of OspC type A strains reflect a broader paradigm across Bb isolates, in which near-clonal genotypes are defined by strain-specific clusters of linked genetic elements, particularly those encoding surface-exposed lipoproteins. These clusters of genes are maintained by strain-specific patterns of plasmid occupancy and are associated with the probability of invasive infection.

Dendritic cell activation and cytokine response in vaccine breakthrough TBE patients after in vitro stimulation with TBEV.

Tick-borne encephalitis (TBE) is a viral infection of the human central nervous system caused by the TBE virus (TBEV). The most effective protective measure against TBE is vaccination. Despite the highly immunogenic vaccine, cases of vaccine breakthroughs (VBTs) occur. One of the first targets of infection is dendritic cells (DC), which represent a fundamental bridge between innate and adaptive immunity through antigen presentation, costimulation, and cytokine production. Therefore, we investigated the activation and maturation of DCs and cytokine production after in vitro TBEV stimulation of peripheral blood mononuclear cells (PBMCs) obtained from VBT and unvaccinated TBE patients. Our results showed that the expression of HLA-DR and CD86 on DCs, was upregulated to a similar extent in both vaccinated and unvaccinated TBE patients but differed in cytokine production after stimulation with TBEV. PBMCs from patients with VBT TBE responded with lower levels of IFN-α and the proinflammatory cytokines IL-12 (p70) and IL-15 after 24- and 48-hour in vitro stimulation with TBEV, possibly facilitating viral replication and influencing the development of cell-mediated immunity. On the other hand, significantly higher levels of IL-6 in addition to an observed trend of higher expression of TNF-α measured after 6 days of in vitro stimulation of PBMC could support disruption of the blood-brain barrier and promote viral and immune cell influx into the CNS, leading to more severe disease in VBT TBE patients.

Association of Persistent Symptoms after Lyme Neuroborreliosis and Increased Levels of Interferon-α in Blood.

Patients who have Lyme neuroborreliosis (LNB) might experience lingering symptoms that persist despite antibiotic drug therapy. We tested whether those symptoms are caused by maladaptive immune responses by measuring 20 immune mediators in serum and cerebrospinal fluid (CSF) in 79 LNB patients followed for 1 year. At study entry, most mediators were highly concentrated in CSF, the site of the infection. Those responses resolved with antibiotic therapy, and associations between CSF cytokines and signs and symptoms of LNB were no longer observed. In contrast, subjective symptoms that persisted after use of antibiotics were associated with increased levels of serum interferon-α (IFN-α), which were already observed at study entry, and remained increased at each subsequent timepoint. Highest IFN-α levels corresponded with severe disease. Although the infection serves as the initial trigger, sequelae after antibiotic therapy are associated with unremitting systemic IFN-α levels, consistent with the pathogenic role of this cytokine in interferonopathies in other conditions.

Whole genome sequencing of Borrelia burgdorferi isolates reveals linked clusters of plasmid-borne accessory genome elements associated with virulence.

Lyme disease is the most common vector-borne disease in North America and Europe. The clinical manifestations of Lyme disease vary based on the genospecies of the infecting Borrelia burgdorferi spirochete, but the microbial genetic elements underlying these associations are not known. Here, we report the whole genome sequence (WGS) and analysis of 299 patient-derived B. burgdorferi sensu stricto ( Bbss ) isolates from patients in the Eastern and Midwestern US and Central Europe. We develop a WGS-based classification of Bbss isolates, confirm and extend the findings of previous single- and multi-locus typing systems, define the plasmid profiles of human-infectious Bbss isolates, annotate the core and strain-variable surface lipoproteome, and identify loci associated with disseminated infection. A core genome consisting of ∻800 open reading frames and a core set of plasmids consisting of lp17, lp25, lp36, lp28-3, lp28-4, lp54, and cp26 are found in nearly all isolates. Strain-variable (accessory) plasmids and genes correlate strongly with phylogeny. Using genetic association study methods, we identify an accessory genome signature associated with dissemination and define the individual plasmids and genes that make up this signature. Strains within the RST1/WGS A subgroup, particularly a subset marked by the OspC type A genotype, are associated with increased rates of dissemination. OspC type A strains possess a unique constellation of strongly linked genetic changes including the presence of lp56 and lp28-1 plasmids and a cluster of genes that may contribute to their enhanced virulence compared to other genotypes. The patterns of OspC type A strains typify a broader paradigm across Bbss isolates, in which genetic structure is defined by correlated groups of strain-variable genes located predominantly on plasmids, particularly for expression of surface-exposed lipoproteins. These clusters of genes are inherited in blocks through strain-specific patterns of plasmid occupancy and are associated with the probability of invasive infection.

Recommendations to Improve Tick-Borne Encephalitis Surveillance and Vaccine Uptake in Europe.

There has been an increase in reported TBE cases in Europe since 2015, reaching a peak in some countries in 2020, highlighting the need for better management of TBE risk in Europe. TBE surveillance is currently limited, in part, due to varying diagnostic guidelines, access to testing, and awareness of TBE. Consequently, TBE prevalence is underestimated and vaccination recommendations inadequate. TBE vaccine uptake is unsatisfactory in many TBE-endemic European countries. This review summarizes the findings of a scientific workshop of experts to improve TBE surveillance and vaccine uptake in Europe. Strategies to improve TBE surveillance and vaccine uptake should focus on: aligning diagnostic criteria and testing across Europe; expanding current vaccine recommendations and reducing their complexity; and increasing public education of the potential risks posed by TBEV infection.

Comparison of laboratory and immune characteristics of the initial and second phase of tick-borne encephalitis.

Tick-borne encephalitis (TBE) usually has a biphasic course which begins with unspecific febrile illness, followed by central nervous system involvement. Because TBE is not yet suspected during the initial phase, knowledge of early TBE pathogenesis is incomplete. Herein we evaluated laboratory and immune findings in the initial and second (meningoencephalitic) phase of TBE in 88 well-defined adult patients. Comparison of nine laboratory blood parameters in both phases of TBE revealed that laboratory abnormalities, consisting of low leukocyte and platelet counts and increased liver enzymes levels, were predominately associated with the initial phase of TBE and resolved thereafter. Assessment of 29 immune mediators in serum during the initial phase, and in serum and cerebrospinal fluid (CSF) during the second phase of TBE revealed highly distinct clustering patterns among the three groups. In the initial phase of TBE, the primary finding in serum was a rather heterogeneous immune response involving innate (CXCL11), B cell (CXCL13, BAFF), and T cell mediators (IL-27 and IL-4). During the second phase of TBE, growth factors associated with angiogenesis (GRO-α and VEGF-A) were the predominant characteristic in serum, whereas innate and Th1 mediators were the defining feature of immune responses in CSF. These findings imply that distinct immune processes play a role in the pathophysiology of different phases of TBE and in different compartments.

Performance of nasopharyngeal swab and saliva in detecting Delta and Omicron SARS-CoV-2 variants.

A prospective cohort study was conducted during the Delta and Omicron severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) epidemic waves from paired nasopharyngeal swab (NPS or NP swab) and saliva samples taken from 624 participants. The study aimed to assess if any differences among participants from both waves could be observed and if any difference in molecular diagnostic performance could be observed among the two sample types. Samples were transported immediately to the laboratory to ensure the highest possible sample quality without any freezing and thawing steps before processing. Nucleic acids from saliva and NPS were prospectively extracted and SARS-CoV-2 was detected using a real-time reverse-transcription polymerase chain reaction. All observed results were statistically analyzed. Although the results obtained with NP and saliva agreed overall, higher viral loads were observed in NP swabs regardless of the day of specimen collection in both SARS-CoV-2 epidemic waves. No significant difference could be observed between the two epidemic waves characterized by Delta or Omicron SARS-CoV-2. To note, Delta infection resulted in higher viral loads both in NP and saliva and more symptoms, including rhinorrhea, cough, and dyspnea, whereas Omicron wave patients more frequently reported sore throat. An increase in the mean log RNA of SARS-CoV-2 was observed with the number of expressed symptoms in both waves, however, the difference was not significant. Data confirmed that results from saliva were concordant with those from NP swabs, although saliva proved to be a challenging sample with frequent inhibitions that required substantial retesting.

Complete Genome Sequencing of Tick-Borne Encephalitis Virus Directly from Clinical Samples: Comparison of Shotgun Metagenomic and Targeted Amplicon-Based Sequencing.

The clinical presentation of tick-borne encephalitis virus (TBEV) infection varies from asymptomatic to severe meningoencephalitis or meningoencephalomyelitis. The TBEV subtype has been suggested as one of the most important risk factors for disease severity, but TBEV genetic characterization is difficult. Infection is usually diagnosed in the post-viremic phase, and so relevant clinical samples of TBEV are extremely rare and, when present, are associated with low viral loads. To date, only two complete TBEV genomes sequenced directly from patient clinical samples are publicly available. The aim of this study was to develop novel protocols for the direct sequencing of the TBEV genome, enabling studies of viral genetic determinants that influence disease severity. We developed a novel oligonucleotide primer scheme for amplification of the complete TBEV genome. The primer set was tested on 21 clinical samples with various viral loads and collected over a 15-year period using the two most common sequencing platforms. The amplicon-based strategy was compared to direct shotgun sequencing. Using the novel primer set, we successfully obtained nearly complete TBEV genomes (>90% of genome) from all clinical samples, including those with extremely low viral loads. Comparison of consensus sequences of the TBEV genome generated using the novel amplicon-based strategy and shotgun sequencing showed no difference. We conclude that the novel primer set is a powerful tool for future studies on genetic determinants of TBEV that influence disease severity and will lead to a better understanding of TBE pathogenesis.

Unique Clinical, Immune, and Genetic Signature in Patients with Borrelial Meningoradiculoneuritis1.

Lyme neuroborreliosis (LNB) in Europe may manifest with painful meningoradiculoneuritis (also known as Bannwarth syndrome) or lymphocytic meningitis with or without cranial neuritis (peripheral facial palsy). We assessed host immune responses and the prevalence of TLR1 (toll-like receptor 1)-1805GG polymorphism to gain insights into the pathophysiology of these conditions. Regardless of LNB manifestation, most mediators associated with innate and adaptive immune responses were concentrated in cerebrospinal fluid; serum levels were unremarkable. When stratified by specific clinical manifestation, patients with meningoradiculoneuritis had higher levels of B-cell chemoattractants CXC motif chemokine ligand (CXCL) 12 and CXCL13 and T-cell-associated mediators CXCL9, CXCL10, and interleukin 17, compared with those without radicular pain. Moreover, these patients had a higher frequency of TLR1-1805GG polymorphism and more constitutional symptoms. These findings demonstrate that meningoradiculoneuritis is a distinct clinical entity with unique immune and genetic pathophysiology, providing new considerations for the study of LNB and borrelial meningoradiculitis.

Clinical and Laboratory Characteristics and Outcome of Illness Caused by Tick-Borne Encephalitis Virus without Central Nervous System Involvement.

Information on febrile illness caused by tick-borne encephalitis virus (TBEV) without central nervous system involvement is limited. We characterized 98 patients who had TBEV RNA in their blood but no central nervous system involvement at the time of evaluation. Median duration of illness was 7 days; 37 (38%) patients were hospitalized. The most frequent findings were malaise or fatigue (98%), fever (97%), headache (86%), and myalgias (54%); common laboratory findings were leukopenia (88%), thrombocytopenia (59%), and abnormal liver test results (63%). During the illness, blood leukocyte counts tended to improve, whereas thrombocytopenia and liver enzymes tended to deteriorate. At the time of positive PCR findings, 0/98 patients had serum IgG TBEV and 7 serum IgM TBEV; all patients later seroconverted. Viral RNA load was higher in patients with more severe illness but did not differ substantially in relation to several other factors. Illness progressed to tick-borne encephalitis in 84% of patients within 18 days after defervescence.

Colocalization of Radicular Pain and Erythema Migrans in Patients With Bannwarth Syndrome Suggests a Direct Spread of Borrelia Into the Central Nervous System.

BACKGROUND: There is a general assumption that after deposition into skin, Lyme borreliae disseminate hematogenously to other organs, resulting in extracutaneous manifestations of Lyme borreliosis, including Lyme neuroborreliosis. However, our experience over the past 40 years, along with several published case reports that observed colocalization of radicular pain and erythema migrans (EM) in patients with borrelial meningoradiculoneuritis (Bannwarth syndrome), argues against hematogenous dissemination in Lyme neuroborreliosis. METHODS: We compared the location of EM in 112 patients with Bannwarth syndrome to 12315 EM patients without neurological involvement. Moreover, we assessed the colocalization of EM and radicular pain in patients with Bannwarth syndrome. RESULTS: Compared to >12000 EM patients without neurological involvement, patients with Bannwarth syndrome had a significantly higher frequency of EM on head/neck (6% vs 1%; P=.0005) and trunk (47% vs 24%; P<.0001), similar frequency on arms (16% vs 16%; P=.91), but lower frequency on legs (30% vs 59%; P<.0001). Moreover, in 79% (89/112) of patients the site of EM matched the dermatomes of radicular pain. The odds for a congruent location of EM and radicular pain were highly significant with the highest odds ratios (OR) observed for head (OR=221), followed by neck (OR=159), legs (OR=69), arms (OR=48), and trunk (OR=33). CONCLUSIONS: The greater frequency of EM on head/neck and trunk and the colocalization of EM with radicular pain in patients with Bannwarth syndrome suggest that central nervous system involvement in Lyme neuroborreliosis is due to a retrograde spread of borrelia from skin to the spinal cord via peripheral nerves.

Clinical Characteristics of Patients with Tick-Borne Encephalitis (TBE): A European Multicentre Study from 2010 to 2017.

Tick-borne encephalitis (TBE) virus is a major cause of central nervous system infections in endemic countries. Here, we present clinical and laboratory characteristics of a large international cohort of patients with confirmed TBE using a uniform clinical protocol. Patients were recruited in eight centers from six European countries between 2010 and 2017. A detailed description of clinical signs and symptoms was recorded. The obtained information enabled a reliable classification in 553 of 555 patients: 207 (37.3%) had meningitis, 273 (49.2%) meningoencephalitis, 15 (2.7%) meningomyelitis, and 58 (10.5%) meningoencephalomyelitis; 41 (7.4%) patients had a peripheral paresis of extremities, 13 (2.3%) a central paresis of extremities, and 25 (4.5%) had single or multiple cranial nerve palsies. Five (0.9%) patients died during acute illness. Outcome at discharge was recorded in 298 patients. Of 176 (59.1%) patients with incomplete recovery, 80 (27%) displayed persisting symptoms or signs without recovery expectation. This study provides further evidence that TBE is a severe disease with a large proportion of patients with incomplete recovery. We suggest monitoring TBE in endemic European countries using a uniform protocol to record the full clinical spectrum of the disease.

Upregulated Intrathecal Expression of VEGF-A and Long Lasting Global Upregulation of Proinflammatory Immune Mediators in Vaccine Breakthrough Tick-Borne Encephalitis.

Although anti-TBE vaccines are highly effective, vaccine breakthrough (VBT) cases have been reported. With increasing evidence for immune system involvement in TBE pathogenesis, we characterized the immune mediators reflecting innate and adaptive T and B cell responses in neurological and convalescent phase in VBT TBE patients. At the beginning of the neurological phase, VBT patients have significantly higher serum levels of several innate and adaptive inflammatory cytokines compared to healthy donors, reflecting a global inflammatory state. The majority of cytokines, particularly those associated with innate and Th1 responses, are highly concentrated in CSF and positively correlate with intrathecal immune cell counts, demonstrating the localization of Th1 and proinflammatory responses in CNS, the site of disease in TBE. Interestingly, compared to unvaccinated TBE patients, VBT TBE patients have significantly higher CSF levels of VEGF-A and IFN-ß and higher systemic levels of neutrophil chemoattractants IL-8/CXCL8 and GROα/CXCL1 on admission. Moreover, serum levels of IL-8/CXCL8 and GROα/CXCL1 remain elevated for two months after the onset of neurological symptoms, indicating a prolonged systemic immune activation in VBT patients. These findings provide the first insights into the type of immune responses and their dynamics during TBE in VBT patients. An observed systemic upregulation of neutrophil derived inflammation in acute and convalescent phase of TBE together with highly expressed VEGF-A could contribute to BBB disruption that facilitates the entry of immune cells and supports the intrathecal localization of Th1 responses observed in VBT patients.

Comparison of Clinical, Laboratory and Immune Characteristics of the Monophasic and Biphasic Course of Tick-Borne Encephalitis.

The biphasic course of tick-borne encephalitis (TBE) is well described, but information on the monophasic course is limited. We assessed and compared the clinical presentation, laboratory findings, and immune responses in 705 adult TBE patients: 283 with monophasic and 422 with biphasic course. Patients with the monophasic course were significantly (p ≤ 0.002) older (57 vs. 50 years), more often vaccinated against TBE (7.4% vs. 0.9%), more often had comorbidities (52% vs. 37%), and were more often treated in the intensive care unit (12.4% vs. 5.2%). Multivariate logistic regression found strong association between the monophasic TBE course and previous TBE vaccination (OR = 18.45), presence of underlying illness (OR = 1.85), duration of neurologic involvement before cerebrospinal fluid (CSF) examination (OR = 1.39), and patients' age (OR = 1.02). Furthermore, patients with monophasic TBE had higher CSF levels of immune mediators associated with innate and adaptive (Th1 and B-cell) immune responses, and they had more pronounced disruption of the blood-brain barrier. However, the long-term outcome 2-7 years after TBE was comparable. In summary, the monophasic course is a frequent and distinct presentation of TBE that is associated with more difficult disease course and higher levels of inflammatory mediators in CSF than the biphasic course; however, the long-term outcome is similar.

Characteristics of spirochetemic patients with a solitary erythema migrans skin lesion in Europe.

Neither pre-treatment characteristics, nor the outcome after antibiotic therapy, have been reported for spirochetemic European patients with Lyme borreliosis. In the present study, patients with a solitary erythema migrans (EM) who had a positive blood culture for either Borrelia afzelii (n = 116) or Borrelia garinii (n = 37) were compared with age- and sex-matched patients who had a negative blood culture, but were culture positive for the corresponding Borrelia species from skin. Collectively, spirochetemic patients significantly more often recalled a tick bite at the site of the EM skin lesion, had a shorter time interval from the bite to the onset of EM, had a shorter duration of the skin lesion prior to diagnosis, and had a smaller EM skin lesion that was more often homogeneous in appearance. Similar results were found for the subset of spirochetemic patients infected with B. afzelii but not for those infected with B. garinii. However, patients with B. garinii bacteremia had faster-spreading and larger EM skin lesions, and more often reported itching at the site of the lesion than patients with B. afzelii bacteremia. Treatment failures were rare (7/306 patients, 2.3%) and were not associated with having spirochetemia or with which Borrelia species was causing the infection.

Are Differences in Presentation of Early Lyme Borreliosis in Europe and North America a Consequence of a More Frequent Spirochetemia in American Patients?

To assess whether differences in presentation between US and European patients with early Lyme borreliosis are due to the lower rate of spirochetemia in Europe, we compared multiple variables for patients with erythema migrans (EM), restricting the analysis to subjects with a positive blood culture at the time of presentation: 93 US patients infected with Borrelia burgdorferi versus 183 European patients infected with Borrelia afzelii (No = 144) or Borrelia garinii (No = 39). Compared to spirochetemic Slovenian EM patients infected with B. afzelii, US patients with a positive blood culture significantly less often recalled a preceding tick bite at the site of the EM skin lesion, had a shorter duration of EM prior to diagnosis and more often had multiple EM lesions, regional lymphadenopathy, constitutional symptoms, an increased ESR value, a low blood lymphocyte count and detectable borrelia antibodies in acute and convalescent phase blood samples. Similar differences were observed when US patients were compared to Slovenian patients with B. garinii infection, but not all reached statistical significance. The findings are comparable to those previously reported for the corresponding skin culture positive patients and do not support the hypothesis that a higher frequency of spirochetemia at the time of presentation in US patients with EM, compared with European EM patients, is the reason for the observed differences.