Lyme borreliosis.

Lyme borreliosis is a complex infectious process that primarily involves the skin, heart, joints, and nervous systems. The infectious agent is the spirochete B burgdorferi, which is transmitted by the Ixodes genus of ticks. The clinical presentations of Lyme disease are protean because of the overlap of stages and varied organ system involvement. Furthermore, as previously mentioned, approximately one-third of Lyme patients are unable to recall a tick bite. Lyme borreliosis should be suspected in anyone with a tick bite. The findings of an EM lesion and flu-like symptoms strongly favor the diagnosis of stage 1 disease. Stage 2 evolves weeks to months after a tick bite, with cardiac and neurological findings as well as musculoskeletal pain. Stage 3 primarily manifests itself as arthritis associated with continuing or additional neurologic complications. Serologic studies are currently the most practical laboratory aid in diagnosis, because almost all infected individuals have a positive antibody response to the spirochete. Treatment with antibiotics usually proves successful, although longer courses of therapy may be needed in later stages of the disease, and some patients may not respond.