Repeated detection of Borrelia burgdorferi DNA in synovial fluid of a child with Lyme arthritis.

In the pathogenesis of late Lyme borreliosis the relative importance of the causative organism, Borrelia burgdorferi, and the immune response of the host, including autoimmune phenomena, is not yet known. We describe a 7-year-old boy with Lyme arthritis from whom two synovial fluid samples were obtained 5 months apart and up to 17 months after the first appearance of arthritis. Both synovial fluid specimens were shown to contain borrelial DNA by nested polymerase chain reaction for the amplification of portions of the genes for flagellin and OspA. Thus, Borrelia burgdorferi may persist within the joint even during late stages of the disease.