Effects of multiple sclerosis and other inflammatory CNS disorders on tick-borne encephalitis serology

The goal of the present study was to investigate whether a direct association exists between false-positive recognition of IgG antibodies and inflammatory changes in the central nervous system (CNS) and whether inflammatory diseases of the CNS affect the specificity of the enzyme-linked immunosorbent assay (ELISA) of tick-borne encephalitis (TBE) virus. A group of patients (1,815), treated in the Department of Neurology, University Hospital of the Saarland, Homburg/Saar, Germany, were tested forTBE IgG antibodies by ELISA. Several subgroups of patients with and without inflammatory changes in the CSF as well as patients with and without confirmed multiple sclerosis (MS) were investigated. Overall, 4.5% of all the 1,815 patients and 4.8% of the patients with inflammatory changes in the CSF but without MS had TBE IgG antibodies. In the subgroup with inflammatory changes in the CSF and MS, 4.4% of the patients were TBE IgG-positive. In the subgroup without inflammatory changes in the CSF, 3.8% of the patients without MS were TBE IgG-positive and 4.9% of the patients with MS were TBE IgG-positive. The rate of TBE IgG positivity was not significantly different in the subgroups with and without inflammatory changes in the CSF (P = 0.45). The comparison of the subgroups with and without MS showed no significant difference in the TBE IgG titer (P = 0.83) as well. This indicates that the specificity of the ELISA was affected neither by inflammatory changes in the CSF nor by MS.