Neuroborreliosis in Swedish Children: A Population-based Study on Incidence and Clinical Characteristics

Borrelia burgdorferi is a common cause of bacterial meningitis, but there are very few studies on incidence in Europe. The aim of this study was to report the incidence and symptoms of neuroborreliosis in Swedish children.

Medical records of children (< 15 years) treated for neuroborreliosis 2002-2014 were studied retrospectively. The patients were identified in the computerized registers of discharge diagnoses at the Departments of Pediatrics and Infectious Diseases in Gothenburg, Borås, Trollhättan and Halmstad using International Classification of Diseases 10 diagnosis codes G51.0, G01.9 and/or A69.1. Of those, patients with symptoms compatible with neuroborreliosis and a white blood cell count in cerebrospinal fluid ≥ 7 cells/mm with ≥ 80% mononuclear cells were included. Only children living in the city of Gothenburg and 10 surrounding municipalities were included.

Five hundred forty-eight children were included. The median age was 7 (1-14) years. The total incidence for the 13-year-period was 2.8/10,000 and remained unchanged during the period. The incidence was significantly higher in rural (4.0/10,000) than in urban municipalities (2.1/10,000). The most common presenting symptoms were headache (n = 335), fatigue (n = 330) and cranial nerve palsies (n = 329). The median duration of symptoms before admittance was 4.0 days for facial palsy and 14.0 days for other symptoms (P < 0.001). The median white blood cell count in cerebrospinal fluid was 129 (7-1069) cells/mm.

This study is the largest so far in a pediatric population. The incidence of neuroborreliosis was higher than in previous European reports. This might be explained by increased Borrelia awareness, the distribution of tick population in Sweden, and the possibility that Swedish children more frequently play outdoors.