Dr. Murai Éva szerk.: Parasitologia Hungarica 24. (Budapest, 1991)

1986 antigen 297 have been used which was isolated from an American case of neuroborreliosis. In the serological reaction there was no detectable difference between the three antigens. Antigenicity was much more influenced by the culture conditions than by differences in the original antigenic structure. That is why a large amount of pooled antigen was produced in March 1987, and it was frozen in small portions. These portions were routinely tested, but a loss of antigenicity was never found. All samples were tested twice, in different series. In the case of discrepancy the test was repeated. IgG antibody was tested only. Serum dilution of at least 1:128 was regarded as positive, which was equivalent to the 95th percentile cut-off level of 200 Hungarian blood donors. Every microscope slide contained three sample drops of control sera: one negative, one borderline and one positive, diluted 1:100. Figure 1 shows that no antibody titer above 1:256 was found among blood donors. This means that the predictive value above this titer is nearly 100%. These high titers were reported to clinicians as "strongly positive". If a titer of 1:256 was found, then the "positive" sign was used with a predictive value of 98.5%. Similarly, 1:128 dilution was equivalent to "weak positive" and 1:64 to "unequivocal" finding. The cut-off level in the CSF was established in the same way. The CSF was drawn from 93 patients subjected to myelography. Only one sample was found to have a titer higher than 1:4; this was accepted as the cut-off level. Borrelia isolation from ticks Thirty-one Ixodes ricinus (17 male, 14 female), five Haemaphysalis inermis (three female, two male) and two H. punctata (male) field collected adult ticks were prepared. Ticks were dissected under stereomicroscope in a drop of BSK medium. One part of the midgut diverticula was dropped into culture media, incubated at 31°C and checked weekly for borrelia. The remaining part was transferred to a microscope slide, covered and depressed with a coverslip and examined under darkfield microscope. The coverslip was then removed and the material was air-dried and fixed in acetone and tested by direct or indirect immunofluorescence. For direct immunofluorescence the preparations were flooded with fluorescein-isothiocyanate-conjugated antibody produced in hyperimmunized rabbits (kindly provided by R. Gustafson, Huddinge Hospital, Stockholm). A serum sample with extremely high antibody titer, drawn from an ACA patient was applied for the indirect immunofluorescence test. The antigenic structure was evaluated by Western blot. Three patients' sera were used as antibody: an American case of Lyme arthritis, a Hungarian arthritic case and a BS patient. All three patients had extremely high borrelia antibody titers. A negative control serum from a blood donor was also applied. Statistical analysis The statistical calculations were done by an ATARI 1040 ST computer with the EPI INFO software developed by the Centers for Disease Control. Fisher's exact test was used for statistical analysis.