Neuroborreliosis in childhood : Clinical, immunological and diagnostic aspects

Sammanfattning: Lyme Borreliosisis is a multi-organ infectious disease caused by the spirochete Borrelia burgdorferi. The spirochete is transmitted to humans by tick bites. Neuroborreliosis (NB) is a disseminated form of the disease, in which the spirochetes invade the nervous system. In children, subacute meningitis and facial nerve palsy are typical clinical manifestations of NB.The aim of this thesis was to study clinical, immunological and laboratory characteristics in children being evaluated for NB in a Lyme endemic area of Sweden, in order to identify factors of importance for prognosis and clinical recovery. A total of 250 patients and 220 controls were included during 1998-2005, with a prospective and a retrospective part.Less than half (41%) of children with signs and symptoms indicative of NB get the diagnosis confirmed by detection of Borrelia specific flagella antibodies in CSF (clinical routine method). Surprisingly few patients were diagnosed as having other infectious or neurologic diseases and consequently, many patients ended up with an uncertain diagnosis. However, four new Borrelia antigens (DbpA, BBK32, OspC, IR6) were evaluated and performed well in laboratory diagnostics. If they were combined in a panel, together with the flagella antigen, the sensitivity was 82% and the specificity 100%, leading to improved diagnostic accuracy in children with NB, as compared to using the routine flagella antibody test alone.Clinical recovery at the 6-month follow-up (n=177) was generally good and nonspecific symptoms, such as headache and fatigue, were not more frequently reported in patients than in controls. No patient was found to have recurrent or progressive neurologic symptoms.However, permanent facial nerve palsy was found in 22% of patients at the 2-year follow-up, with consequences such as eye-closing problems, excessive tear secretion, pronunciation difficulties and cosmetic complaints.When cellular immune responses were investigated, the number of Borrelia-specific IL-4 and IFN-γ secreting cells in CSF was found to be more prominent in children with NB than in controls. Furthermore, a much stronger IL-4 response in CSF was seen in children as compared to adults with NB. This cytokine profile of children with NB is believed to represent an effective and balanced type1/type2 response in a relevant compartment, and could contribute to the less severe course of the disease seen in children as compared to adults with NB.No prognostic factors were found to influence the outcome in patients with “Confirmed NB” or facial nerve palsy. Nor was any specific cytokine profile, or antibody response to new Borrelia antigens in CSF, correlated to a less favorable clinical outcome.An NB prediction score test, based on clinical variables at admission, is suggested to help physicians to determine whether to start early antibiotic treatment, before results from Borrelia antibody tests are available.Results in this thesis support the notion that mononuclear pleocytosis in CSF, in patients being evaluated for NB, indicates that they are true NB cases despite the fact that an antibody response cannot yet be visualized. with the routine flagella test. Consequently, early antibiotic treatment in NB seems to be the correct course of action and over-treatment is not a substantial problem.