Infection with Borrelia spp. is the most common vector borne infection in Europe with an estimated more than 60,000 symptomatic cases annually and a reported incidence from Germany of about 1 per 1,000 population . Infection may result in a variety on clinical symptoms, including neuroborreliosis with cranial nerve paresis and radicular pain. Borrelia infections in humans are caused by B. afzelli, B. garinii and B. burgdorferi sensu stricto. A study from Germany found that 65% of patients were infected with B. garinii, 24% with B. afzelii and 11% with B. burgdorferi sensu stricto . Clinical borrelia infection is divided in three stages, 1) erythema migrans; 2) multiple erythema migrans, lymphadenosis benigna cutis, neuroborreliosis and myocarditis; and 3) arthritis, acrodermatitis chronica athrophicans and chronic neuroborreliosis .
The diagnosis of neuroborreliosis is difficult. It relies primarily on clinical signs, demonstration of intrathecal antibody synthesis and pleocytosis in the spinal fluid . Antibody based assays suffers from lack of standardization , and borrelia infection is therefore overdiagnosed based on vague criteria and equivocal serological results especially IgM positivity without specific IgG-antibodies . Nucleic acid based molecular diagnosis has an even lower sensitive .
Borrelia spp. is believed to express different antigens in different hosts , gene expression is reduced as the Borrelia adapt to the host [9, 10] and consequently serological diagnosis is difficult and unpredictable in the early stages of the infection. This partly explains why common consensus on diagnostic criteria is lacking . The flagella contain the immunodominant 41 kDa, flagellin antigen, and several outer surface proteins, Osp's. The use of an enzyme-immunoassay followed by a Western blot or dot blot assay has not improved diagnostic accuracy . However, Western blotting with a mixture of B. burgdorferi sensu stricto and B. afzelii antigens have been found to improve diagnosis in up to 70% of sera with borderline results , but Western blot or immunoblots using recombinant antigens can not be regarded as a golden reference standard . Antibody assays have not been useful in the diagnosis of erythema migrans. Patients with systemic Borrelia infections show IgG-antibodies after up to eight weeks after infection . Persistent IgM-antibodies with without development of Borrelia-specific IgG-antibodies is usually regarded as false-positive reactions .
The two diagnostic assays have previously been evaluated on patients with well defined clinical borrelia infection in different stages. In patients with erythema migrans, the flagella assay were found to have a sensitivity of 44.8% in the IgM assay and 35.5% in the IgG assay , while the recombinant antigen showed a sensitivity of 46.9% in the IgM assay and 66.3% in the IgG assay .
In patients with neuroborreliosis the flagella assay displayed a sensitivity of 67.9% for the IgM assay an 76.8% for the IgG assay , whereas the recombinant antigen assay was found to have a sensitivity of 36.8% for the IgM assay an 90.8% for the IgG assay .
The aim of the present study was to evaluate chemiluminescence immuno assays based on recombinant antigens (LIAISON®, DiaSorin, Salugia, Italy) and assays based on purified flagella antigen (IDEIA™, Dako Cytomation, Glostrup, Denmark). This comparison was performed on a population based panel of samples submitted from general practice for analysis for Borrelia IgM- and IgG-antibodies. In order to compare the two assays, samples with discordant outcome were analysed by a Lineblot (EcoLine, Virotech) to more correctly ascertain the serological status of the patient.