ABSTRACT
Background
Lyme borreliosis is a zoonosis caused by bacteria from Borrelia burgdorferi sensu lato complex. In Europe, it is transmitted to humans by infected Ixodes ricinus ticks. During dissemination, when borreliae reach the nervous system, manifestations of Lyme neuroborreliosis develop. In adult European patients, Lyme neuroborreliosis is mainly caused by B. garinii, followed by B. afzelii, and B. burgdorferi. In adult patients, it has been corroborated that the clinical presentation of Lyme neuroborreliosis depends on B. burgdorferi sensu lato species. However, data on the etiology of Lyme neuroborreliosis in children in Europe is limited, with only scarce data about the influence of B. burgdorferi sensu lato species isolated from CSF on clinical presentation of Lyme neuroborreliosis in children.
Hypothesis
In the present study, we wanted to confirm two hypotheses. First, that B. garinii is the main cause of Lyme neuroborreliosis in children in Slovenia, as in adult patients, and second, that the clinical presentation of Lyme neuroborreliosis in children depends on the B. burgdorferi sensu lato species that caused it.
Methods
The study was mono-centric. During its 17-year period, it included children younger than 15 years with clinical presentation suggestive of Lyme neuroborreliosis or confirmed Lyme borreliosis, who had B. burgdorferi sensu lato isolated from CSF, and who had the species of B. burgdorferi sensu lato identified by pulsed-field gel electrophoresis. Demographic and medical data were compared for children infected with various B. burgdorferi sensu lato species. Machine learning analysis was performed to search through chosen variables for the variable with the highest relative importance score in order to classify children with Lyme neuroborreliosis caused by various B. burgdorferi sensu lato species.
Results
153 children had Borrelia burgdorferi sensu lato isolated from CSF. In 71/113 (62.8%) B. garinii, and in 42/113 (37.2%) B. afzelii were identified. Most cases of Lyme neuroborreliosis in children occurred between May and August compared to the period from September to April (69.0% vs. 31.0%, p=0.012).
Patients infected with B. garinii did not report symptoms suggestive of central nervous system involvement or any other symptoms more often than patients infected with B. afzelii. In children infected with B. garinii, erythema migrans was seen as the first sign/symptom less often (21.1% vs. 45.2%, padj=0.021) compared with children infected with B. afzelii and multiple erythema migrans were observed less often on clinical examination (18.3% vs. 45.2%, padj=0.036). However, children infected with B. garinii presented symptoms of meningitis as the first sign/symptom (57.7% vs. 28.6%, padj=0.012), had positive meningeal signs on clinical examination (69.0% vs. 38.1%, padj=0.019), had CSF lymphocytic predominance (92.9% vs. 65.0%, padj=0.008 ), and had elevated albumin CSF/serum quotient (80.6% vs. 50.0%, padj=0.038) more often than children infected with B. afzelii.
There were no statistically significant differences in laboratory blood findings, in the presence of specific borrelial antibodies in serum and CSF, and in intrathecal specific borrelial antibody production between groups of patients infected with B. garinii and B. afzelii.
The variable with the highest relative importance score for classification between groups of children with Lyme neuroborreliosis caused by B. garinii and B. afzelii is CSF lymphocyte concentration, followed by CSF albumin level, and CSF white blood cell count.
Conclusions
In Slovenia, Lyme neuroborreliosis in children is more often caused by B. garinii, followed by B. afzelii. This confirms our first hypothesis. Signs and symptoms of Lyme neuroborreliosis in children caused by B. garinii are not more often suggestive of CNS involvement, but CNS inflammation is more pronounced in children infected with B. garinii, compared with children infected with B. afzelii. Thus, the whole clinical presentation of Lyme neuroborreliosis in children depends on B. burgdorferi sensu lato species. This confirms our second hypothesis.
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