Utility of a commercial immunoblot kit (BAG-Borrelia blot) in the diagnosis of the preliminary stages of Lyme disease.

The aim of this study was to evaluate the usefulness of a commercial immunoblot (IgG and IgM BAG-Borrelia blot) in the serologic diagnosis of the early stages of Lyme disease. A total of 42 sera from patients with Lyme disease (24 patients with localized early stage (LES) and 18 patients with disseminated early stage (DES)) and 129 sera from patients with non-Lyme diseases (specificity control sera) were studied. IgG anti-p41 from Borrelia burgdorferi s.l. was present in 95.2% of patients followed by anti-p41/I PBi (16.7%), anti-p100 (9.5%) and anti-OspA (9.5%). IgM anti-p41 was present in 66.7% of patients, p41/iPBi (54.8%) and OspC (33.3%). IgM against p100, OspA and OspC were more frequent in DES patients (16.7%, 27.8% and 44.4%) than in LES patients (0.0%, 4.2% and 25.0%). In 4.8% of the cases no IgG bands were present and in 26.2% no IgM bands were present. With the exception of isolated p41 bands (59.5%), no band pattern exceeded 17%. Using manufacturer's instructions, test sensitivity in diagnosis of the early stage of Lyme disease is 61.9%, specificity 98.4% and positive and negative predictive values 92.8% and 88.8% respectively. Applying the EUCALB 5, 6 or 7 rules sensitivity increased to 73.8% although specificity decreased to 89.9%. Of the 129 specific control sera, 41.8% presented IgG anti-p41 and 10.8% IgM anti-p41. Patients with non-Lyme diseases that presented more IgG and IgM bands were those patients with syphilis (88.2%), patients with anti-HIV antibodies (57.8%) and patients with anti-nuclear antibodies (ANA) (52.3%).