Diagnosis of Lyme disease. Current difficulties and prospects.

Articular manifestations of Lyme disease may be less common in Europe than in the United States, perhaps because European strains of Borrelia burgdorferi are characterized by greater genetic diversity and different organotropisms as compared with American strains. The diagnosis rests on clinical symptoms. A history of erythema migrans is pathognomonic. Isolated articular manifestations with no history of erythema migrans raise difficult diagnostic problems. Monoarthritis and asymmetric oligoarthritis is the most characteristic pattern; enthesitis can occur, a clinical feature shared with spondylarthropathy. Serologic tests (indirect immunofluorescence, Western blotting) have not been standardized and should be used only to confirm the diagnosis in patients with suggestive clinical manifestations. The interpretation of serologic test results is made difficult by the high seroprevalence rates seen among the general population in endemic areas, where subclinical Borrelia burgdorferi infection probably occurs. Detection of Borrelia burgdorferi DNA using polymerase chain reaction amplification is a potent tool both for diagnosis and for gaining insight into the pathophysiology of Lyme disease. However, difficulties subsist (risk of contamination of the specimens, inhibitory effects). Continued work is needed to determine which targets (chromosomal DNA, plasmidic DNA) and specimens (joint fluid and/or synovial membrane) provide optimal results.