PREVALENCE OF ANTIBODIES TO TICK-BORNE ENCEPHALITIS-VIRUS AND BORRELIA-BURGDORFERI SENSU-LATO IN SAMPLES FROM PATIENTS WITH ABNORMALITIES IN THE CEREBROSPINAL-FLUID

Within the last few years, an increase in cases of tick-borne encephal itis (TBE) as well as an expansion of TEE-endemic regions have been no ted in southern Germany. In 1994, a patient was diagnosed for the firs t time with TEE that had been acquired in Saarland. Up to this point, the Saarland had been considered TEE-free. In a retrospective study, w e tested serum samples from 904 patients with abnormalities in the cer ebrospinal fluid (CSF) for TEE antibodies. The IgG ELISA used (Immunoz ym-FSME-IgG(R), Immune GmbH, Heidelberg, Germany) yielded 47 positive and 134 borderline sera. The percentage of positive sera showed a sign ificant increase during the time period studied (1989-1994): One IgG-p ositive serum sample was also IgM-positive. Of the CSF samples, 2 were IgG-positive and 7 were borderline for IgG. In three patients, a posi tive intrathecal antibody index (IAI) was found, indicating an intrath ecal antibody production. An analysis of the vaccination history of th e patients showed that only 19% of the patients with a positive TEE Ig G titre and only 5.9% of the borderline patients had been vaccinated a gainst TEE. We compared 98 patients that tested positive or borderline for TEE IgG with 98 sex-and-age-matched patients that tested negative . The parameters studied included the patient's complaints upon discha rge, the average duration of stationary treatment and 16 different neu rological symptoms. We did not observe any significant differences bet ween the two groups. We also tested the sera of 704 of the 904 patient s for antibodies to Borrelia burgdorferi (Borrelia burgdorferi ELISA, Genzyme Virotech GmbH, Russelsheim, Germany). 155 (22.0%) of the sera were IgG-positive, 136 (19.3%) were borderline, 32 patients (4.6%) had a positive intrathecal antibody index (IAI). The fact that no patient with a clinically manifest case of TEE had acquired the disease in th e Saarland indicates that the actual risk of acquiring an acute TEE in the Saarland is very low, despite the high percentage of samples that tested positive for IgG in the ELISA. The increase in the number of s erum samples that tested positive for TEE IgG during the last years co uld be explained by an expansion of TEE regions into the Saarland, inc reasing vaccination of the population or more travel to endemic region s. The proportion of patients with IgG antibodies to Borrelia was 22%. Because only part of the patients suffered from an acute, clinically manifest borreliosis, and since the serum Ige titre had remained posit ive for many years after contact with the microorganisms, we suspected that a large percentage of the population would show signs of a clini cally silent infection in their sera. 4.6% of the patients had a posit ive IAI quotient, a clear indication of neuroborreliosis.