Background: The broad variations in the clinical manifestation in Lyme borreliosis underline the importance of laboratory investigations in serum and cerebrospinal fluid.
Material and methods: We have studied patients with neurological signs compatible with Lyme neuroborreliosis, pleocytosis in cerebrospinal fluid and positive Borrelia serology in serum/cerebrospinal fluid analysed by ELISA. We have evaluated clinical characteristics, laboratory parameters, treatment effects, and incidence variations.
Results: We included 25 patients in the study. Isolated facial palsy was often seen, but clinical manifestations showed huge variation. Fourteen of 25 (56%) patients had positive Borrelia burgdorferi-IgM and IgG titres in cerebrospinal fluid despite negative tests in serum. The mean annual incidence rate in the county judged by notified cases to the Norwegian Surveillance System for Communicable Diseases (MSIS) was 4.4/100,000 in the period 1989-99 as compared to the national rate of 4.3/100,000 in the same period. In 1998, however, the annual incidence rate in the county was 8.8/100,000 as compared to the national rate of 4.1/100,000.
Interpretation: The diversity of symptoms and signs suggests a liberal attitude towards serological testing including CSF analyses. Møre and Romsdal is a high incidence region for Lyme borreliosis in Norway. The annual variation in incidence might reflect a changing prevalence of the tick vector along the Norwegian coastline.