Katarina Ogrinc

Background/Objectives: The diagnosis of typical erythema migrans (EM) is clinical, and serological testing for Borrelia-specific antibodies is not required. However, characterization of the immune response in patients with a reliable clinical diagnosis may improve the interpretation of serological findings in early Lyme borreliosis (LB) without characteristic skin lesions. Methods: Serum IgM and IgG antibodies to Borrelia burgdorferi sensu lato were evaluated in 1356 Slovenian adults with EM at baseline and at a follow-up visit approximately two months after treatment initiation, using a chemiluminescence immunoassay based on recombinant borrelial antigens. Results: At baseline, 41.5% of patients were IgM-seropositive, 55.5% IgG-seropositive, and 70.1% positive for either IgM or IgG. Patients with multiple EM were significantly more often seropositive than those with solitary EM. In previously untreated patients, baseline IgG seropositivity showed a clearer positive association with longer lesion duration and larger lesion diameter, whereas the corresponding IgM patterns were less consistent. Multiple EM remained strongly associated with both IgM and IgG seropositivity in adjusted analyses. Seroconversion at follow-up was uncommon, occurring in 8.0% of initially IgM-negative and 8.2% of initially IgG-negative patients. Conclusions: The low frequency of newly detectable antibody responses indicates that repeat qualitative serologic testing approximately two months after treatment initiation provides limited additional diagnostic information in European adults with EM.

Background: Early European lyme neuroborreliosis (LNB) presents with distinct clinical manifestations, but comparative data on cerebrospinal fluid (CSF) findings across these forms are limited. Methods: We conducted a retrospective study of 405 patients with confirmed early LNB treated at a single center between 2005 and 2025. Thirteen routine CSF parameters were analyzed across three main clinical manifestations—meningoradiculoneuritis (Bannwarth syndrome), cranial neuritis, and erythema migrans (EM)-associated meningitis—and in relation to the duration of neurological symptoms. Multivariate regression was used to assess independent associations. Results: Of 405 patients, 274 (68%) had Bannwarth syndrome, 82 (20%) cranial neuritis, and 49 (12%) EM-meningitis. CSF abnormalities differed significantly among groups and were most pronounced in Bannwarth syndrome and least marked in EM-meningitis. Patients with Bannwarth syndrome more frequently had positive borrelial serology and intrathecal antibody synthesis. CSF leukocyte counts, protein, and albumin increased during the first 4 weeks of disease and then stabilized, whereas immunoglobulin levels peaked around week 6. Longer duration of neurological symptoms was associated with higher lymphocyte proportion, increased protein levels, and elevated IgM and IgG concentrations. Multivariate analysis confirmed that clinical manifestation, symptom duration, age, and sex independently influenced CSF parameters. Conclusions: The three principal manifestations of early European LNB differ in the magnitude of CSF inflammation and blood–brain barrier dysfunction. Bannwarth syndrome is associated with the most pronounced intrathecal inflammatory response, whereas EM-associated meningitis represents a milder phenotype. CSF abnormalities evolve over time, underscoring the importance of early diagnostic evaluation.

Objectives: Borrelia burgdorferi sensu lato, a spirochete bacterium responsible for Lyme borreliosis—the most common tick-borne infection in North America and Europe—can trigger the production of antiphospholipid antibodies. These antibodies target host lipids such as cardiolipin (CL), phosphatidic acid (PA), phosphatidylcholine (PC), and phosphatidylserine (PS), which the spirochete incorporates into its membrane from the surrounding environment. Although antiphospholipid antibodies are typically associated with antiphospholipid syndrome (APS), they may also arise during infections, including Lyme borreliosis. This study aimed to develop and optimize several enzyme-linked immunosorbent assays (ELISAs) for measuring various antiphospholipid antibodies in patients with Lyme borreliosis. Methods: Thirty patients diagnosed with Lyme borreliosis were enrolled: ten with solitary erythema migrans (EM), ten with multiple EM (MEM), and ten with late manifestations known as acrodermatitis chronica atrophicans (ACA). Forty healthy blood donors served as controls. Four distinct antiphospholipid antibody ELISAs were developed, each using a different phospholipid coating: CL, PA, PC, and PS. Serum of APS patient was used as a positive control and for standard curve generation. Results: All four ELISAs were successfully established and demonstrated good measurement precision. Significant differences in antiphospholipid antibody levels and positivity rates were observed between Lyme borreliosis patients and healthy blood donors. Notably, levels of antibodies directed against PA (aPA), PC (aPC), and PS (aPS), both IgG and IgM, were significantly higher in patients with late Lyme borreliosis, manifested as ACA, compared to healthy blood donors. In contrast, anti-CL (aCL) levels did not differ significantly between groups. Patients with ACA also showed the highest frequency of multiple antiphospholipid antibody positivity, with 7 out of 10 patients testing positive for three or more antiphospholipid antibodies. Conclusions: Accurate and precise in-house ELISAs for the detection of aCL, aPA, aPC, and aPS using APS sera as standard material were developed and validated for the analysis of samples of patients with Lyme borreliosis. Our data suggest that antiphospholipid antibody levels—specifically aPA, aPC, and aPS—differ across clinical manifestations of Lyme borreliosis, with the greatest increases observed in patients with ACA.

Objectives: Borrelia burgdorferi sensu lato, a spirochete bacterium responsible for Lyme borreliosis - the most common tick-borne infection in North America and Europe - can trigger the production of antiphospholipid antibodies. These antibodies target host lipids such as cardiolipin (CL), phosphatidic acid (PA), phosphatidylcholine (PC), and phosphatidylserine (PS), which the spirochete incorporates into its membrane from the surrounding environment. Although antiphospholipid antibodies are typically associated with antiphospholipid syndrome (APS), they may also arise during infections, including Lyme borreliosis. This study aimed to develop and optimize several enzyme-linked immunosorbent assays (ELISAs) for measuring various antiphospholipid antibodies in patients with Lyme borreliosis. Methods: Thirty patients diagnosed with Lyme borreliosis were enrolled: ten with solitary erythema migrans (EM), ten with multiple EM (MEM), and ten with late manifestations known as acrodermatitis chronica atrophicans (ACA). Forty healthy blood donors served as controls. Four distinct antiphospholipid antibody ELISAs were developed, each using a different phospholipid coating: CL, PA, PC, and PS. Serum of APS patient was used as a positive control and for standard curve generation. Results: All four ELISAs were successfully established and demonstrated good measurement precision. Significant differences in antiphospholipid antibody levels and positivity rates were observed between Lyme borreliosis patients and healthy blood donors. Notably, levels of antibodies directed against PA (aPA), PC (aPC), and PS (aPS), both IgG and IgM, were significantly higher in patients with late Lyme borreliosis, manifested as ACA, compared to healthy blood donors. In contrast, anti-CL (aCL) levels did not differ significantly between groups. Patients with ACA also showed the highest frequency of multiple antiphospholipid antibody positivity, with 7 of 10 patients testing positive for three or more antiphospholipid antibodies. Conclusions: Accurate and precise in-house ELISAs for the detection of aCL, aPA, aPC, and aPS using APS sera as standard material were developed and validated for the analysis of samples of patients with Lyme borreliosis. Our data suggest that antiphospholipid antibody levels—specifically aPA, aPC, and aPS—differ across clinical manifestations of Lyme borreliosis, with the greatest increases observed in patients with ACA.

Purpose To determine the frequency of confirmed Lyme neuroborreliosis (LNB) cases in adult patients with three different clinical presentations consistent with early LNB. Methods Data were obtained through routine health care at the UMC Ljubljana, Slovenia from 2005 to 2022, using clinical pathways. The patients were classified into three groups: (i) radicular pain of new onset (N = 332); or (ii) involvement of cranial nerve(s) but without radicular pain (N = 997); or (iii) erythema migrans (EM) skin lesion(s) in conjunction with symptoms suggestive of nervous system involvement but without either cranial nerve palsy or radicular pain (N = 240). The diagnosis of LNB considered the following variables: the presence of: (1) neurologic symptoms consistent with LNB (with no other obvious explanation); (2) cerebrospinal fluid (CSF) pleocytosis (> 5 × 10⁶ leukocytes/L); and (3) demonstration of intrathecal synthesis of borrelial antibodies, and/or cultivation of borrelia from CSF, and/or the presence of EM. Patients fulfilling only the first two criteria were interpreted as having possible LNB, while those who satisfied all three criteria were regarded as having confirmed LNB. Results Of 1569 adult patients, 348 (22.2%) had confirmed LNB and 70 (4.5%) others had possible LNB. The proportion of confirmed LNB cases was the highest for patients with radicular pain (217/332, 65.4%), followed by the group with EM and neurologic symptoms (47/240, 19.6%), and those with cranial neuritis (84/997, 8.4%). Conclusion Only 22% of patients evaluated had confirmed LNB. The proportion of confirmed LNB cases correlated with clinical presentation and was highest among patients with recent onset of radicular pain.

Information on asplenic Lyme borreliosis (LB) patients with erythema migrans (EM) is lacking. We compared the course and outcome of 26 EM episodes in 24 post-trauma splenectomized patients (median age 51 years) diagnosed at a single clinical center in Slovenia during 1994–2023 with those of 52 age- and sex-matched patients with EM but with no history of splenectomy. All patients were followed for one year. A comparison of pre-treatment characteristics revealed that EM in splenectomized patients was of shorter duration before diagnosis (4 vs. 8 days, p = 0.034) with a smaller EM diameter (10.5 vs. 14 cm, p = 0.046), and more frequently fulfilled criteria for disseminated LB (3/26, 11.5% vs. 0%, p = 0.034). Treatment failure occurred in 5/26 (19.2%) EM episodes in splenectomized patients versus 0/52 in non-splenectomized patients (p = 0.003). The five treatment failure cases were retreated with antibiotic regimens used to treat EM and had complete resolution of all symptoms/signs. In conclusion, our study showed that splenectomized adult patients with EM differ somewhat in presentation and more often have treatment failure compared with non-splenectomized patients with EM.

Purpose: Diagnosis of (European) Lyme neuroborreliosis has been based on clinical presentation, cerebrospinal fluid (CSF) pleocytosis and demonstration of intrathecal borrelial antibody synthesis (ITBAS) to document Borrelia burgdorferi s. l. infection. It is not known if other criteria to document Borrelia infection may contribute to the diagnosis. Methods: We compared the sensitivity of three individual criteria (ITBAS, CSF Borrelia culture, and the presence of erythema migrans [EM]) to confirm the diagnosis of early Lyme neuroborreliosis in 280 patients ≥ 15 years of age evaluated at a Lyme borreliosis outpatient clinic in Slovenia. The patients had either radicular pain of new onset or involvement of a cranial nerve but without radicular pain, each in conjunction with CSF pleocytosis. Evaluation was of patients who had each of the three confirmatory criteria assessed, and for whom at least one criterion was positive. Results: Analysis of 280 patients, 120 women and 160 men, median age 57 (range 15–84) years, revealed that ITBAS was the most frequently observed positive criterion (85.4%), followed by EM (52.9%), and by a positive CSF Borrelia culture (9.6%). Of the 280 patients, 154 (55%) met only one criterion (43.2% ITBAS only, 10.7% EM only, and 1.1% positive CSF culture only), whereas 42.1% met two criteria. Only 2.9% of patients were positive by all three criteria. Conclusion: Although ITBAS was the most frequent criterion for confirmation for Borrelia infection, the presence of EM alone confirmed an additional 10.7% of patients and a positive CSF Borrelia culture alone added another 1.1%.

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.

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.

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. 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. 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). 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.