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Tick-borne encephalitis, TBE, has been observed in Aland Islands (population 26,500) for more than 60 years. Because of the small population, the relative incidence is high. Antibodies to TBE virus have been found in ca. 5% of healthy blood donors, indicating that subclinical infection must be common. This study is a review of the symptoms and signs of all the 301 serologically verified cases of TBE seen in Aland during 1959-2005. It also aims at analysing any possible changes in the symptoms and signs of TBE over time. The annual number of patients has been from 1 to 26, and has increased over time. The clinical picture has not undergone any conspicuous changes during these years. A few patients have had permanent neurological damage. There were no certain deaths from TBE. Simple practical measures may be taken to diminish, but not to eliminate, the risk of tick bites. Vaccination of exposed people is recommended, and general vaccination against TBE has commenced in Aland, beginning 2006. This is expected to reduce the incidence of TBE among the population to almost nil, provided that new inhabitants are vaccinated and that booster vaccinations are carried out as required.

Borrelial protein BBK32 was evaluated as an antigen in the serodiagnosis of early and disseminated Lyme borreliosis (LB). bbk32 was cloned and sequenced from eight isolates of the three pathogenic Borrelia species. The identities between the amino acid sequences of the BBK32 proteins from Borrelia burgdorferi sensu stricto, B. garinii , and B. afzelii isolates were 71 to 100%. By immunoglobulin G (IgG) Western blotting (WB) or enzyme-linked immunosorbent assay (ELISA), up to 74 and 100% of acute- and convalescent-phase samples, respectively, from 23 patients with erythema migrans (EM) were positive for recombinant BBK32 protein from B. afzelii . In the serology of disseminated LB, the three variant BBK32 antigens cross-reacted. In total, 14 of 14 samples from patients with neuroborreliosis and 15 of 15 samples from patients with Lyme arthritis were positive. The specificities of the IgG ELISA with the variant BBK32 antigens for EM and disseminated borreliosis were 81 to 92% and 89 to 95%, respectively. Our findings indicate that the BBK32 proteins are promising serodiagnostic antigens for the detection of early and disseminated LB but that variant BBK32 proteins may be needed either in parallel or in combination with an immunoassay for LB to cover all the relevant borrelial species that cause the disease.

Erythema migrans is the most common manifestation of stage I Lyme borreliosis. This study investigated the relation between the subspecies of Borrelia burgdorferi involved, the time of development and the appearance of the manifestation. The study comprised 33 cases of erythema migrans yielding B. burgdorferi sensu lato by culture of skin biopsy. The species was determined by polymerase chain reaction analysis of the cultivated spirochaetes. In 22 of the cases, B. afzelii was demonstrated, whereas 11 yielded growth of B. garinii. All 11 erythemas associated with B. garinii were homogeneous, whereas 20 of the 22 associated with B. afzelii were annular. The garinii erythemas developed more rapidly, and were generally larger than the afzelii erythemas. The observations call for comparison with other geographical areas with similar, and with different, borrelial infection spectra.

A strong initial inflammatory response is important in neuroborreliosis. Since complement is a main player in early inflammation, we monitored the concentration and activation of complement in plasma and cerebrospinal fluid from 298 patients, of whom 23 were diagnosed with neuroborreliosis. Using sandwich ELISAs, we found significantly elevated levels of C1q, C4, C3, and C3a in cerebrospinal fluid, but not in plasma, in patients with neuroborreliosis. This finding indicates that complement plays a role in the human immune response in neuroborreliosis, that the immunologic process is compartmentalized to the CNS, and that complement activation may occur via the classical pathway.

Three recombinant antigens, decorin binding protein A (DbpA), BBK32, and outer surface protein C (OspC), and IR 6 peptide of borrelial VlsE protein, were evaluated for the diagnosis of neuroborreliosis (NB), using cerebrospinal fluid (CSF) and serum samples from 89 patients. Their performances in enzyme-linked immunosorbent assay (ELISA) were compared with that of commercial flagella antigen. IgG ELISAs were performed with three variants of each recombinant antigen originating from Borrelia burgdorferi sensu stricto, B. afzelii and B. garinii, and with the IR 6 peptide. IgM antibodies were analysed against OspC and flagella. Of the patients whose CSF contained elevated anti-flagella IgG antibodies, 93 % were positive for at least three of the new antigens. Of those with negative or borderline CSF anti-flagella antibodies, 51% were positive for three new antigens. Antibodies to BBK32 were detectable mainly in early disease. Antibodies to DbpA and IR 6 were observed in early and late NB. The use of the new antigens at presentation of the disease improved the laboratory diagnosis of NB. In IgG ELISAs, the diagnostic sensitivity of assays with the new antigens was between 75 and 88 %, but was only 52 % with the flagella antigen. The discriminatory power between patient and control samples appeared better in the CSF than in the serum. We suggest that assessment of CSF antibodies to at least two antigens, using either flagella and one of the new antigens or two of the new antigens, would improve the current diagnostic yield of NB.

This is a study of people living in Aland, a group of islands in the Baltic Sea between Finland and Sweden. 500 blood donors and 3,248 health service clients who did not have Lyme borreliosis were examined for Borrelia burgdorferi IgG antibodies. The method used was an ELISA containing a selection of diagnostic antigens to a Borrelia burgdorferi PKo strain. It was found that the distribution according to sex, age and titre values was identical in the 2 groups, which were therefore treated as one. 19.7% of all the sera was positive. The prevalence in men was 23.6%, and in women 16.7%. The prevalence rises with age, the highest prevalence being seen in men (44.7%) and women (37.0%) over 70 y of age. The data show that the Aland islands are strongly endemic for Lyme borreliosis compared with international levels of infection.