Evaluation of immunofluorescence test (IFT) and immuno (western) blot (WB) test in patients with erythema migrans

The diagnosis of Lyme borreliosis is based on the recognition of typical clinical signs and is assisted by laboratory confirmation of borrelial infection. The aim of the present study was to assess the value of an immunofluorescence test (IFT) and an immuno (western) blot (WB) test for the detection of Borrelia burgdorferi sensu lato antibodies in patients with erythema migrans residing in Slovenia. We determined specific IgM and IgG antibodies in 117 patients with erythema migrans and 96 healthy persons using an IFT (in-house test) and a commercial WB test. Skin biopsies of erythema migrans lesions were cultured, and isolated strains were identified with PFGE. There were 66/117 (56.4%) culture-positive and 51/117 (43.6%) culture-negative patients. B. afzelii was found in 52/62 (84%) and B. garinii in 10/62 (16%) biopsies. IFT-IgM antibodies were established in 2/117 (1.7%) erythema migrans patients and in none of the control group, while WB-IgM antibodies were present in 56/117 (48%) patients with erythema migrans and 21/96 (22%) members of the control group (p = 0.002). IFT-IgG antibodies were demonstrated in 3/117 (2.2%) erythema migrans patients and 2/96 (4%) persons of the control group, while corresponding values for WB-IgG were 36/117 (31%) and 26/96 (27%), respectively (non-significant differences). IgM antibodies directed against p41 and OspC, and IgG antibodies directed against p41, p18 and OspC were frequently found in both erythema migrans patients and the control group. The only significant difference between erythema migrans patients and the control group in the WB test was in the reaction of IgM antibodies with OspC antigen, which was found in 54/117 (46%) erythema migrans patients and 18/96 (18.8%) healthy persons (p < 0.0001). The immune response in patients with erythema migrans was very similar to that of the control group determined with either the IFT or WB test.