Lyme disease has as its hallmark erythema migrans. However, it is only present in about one half of the patients who contract this
disease. In its absence, the diagnosis of
Lyme disease may be difficult. It depends upon a compatible history of exposure and clinical signs and symptoms together with positive results of serologic testing. Unfortunately, seronegativity for antibody to the pathogen may occur both during the first six weeks of infection and be chronic due to the reactive antibody being bound in immune complexes. The selective use of new diagnostic tests may be required to confirm the diagnosis. These tests include assays for antibody or antigen analysis of immune complex components, as well as polymerase chain reactions.