The human borreliosis: Lyme neuroborreliosis and relapsing fever

Abstract

Lyme disease, caused by the tick-borne spirochete Borrelia burgdorferi, infects the nervous system in up to 15% of patients. Involvement can include the peripheral nervous system, with a mononeuropathy multiplex manifest as a radiculopathy, cranial neuropathy, plexopathy, or confluent mononeuropathy multiplex. In most instances, central nervous system involvement is limited to meningitis; rarely the spinal cord or brain parenchyma can be involved. Recent work has shed light on the pathophysiologic sequence that results in neuroborreliosis, including early CNS invasion, CXCL13-stimulated B cell entry into and proliferation within the CNS, and then a prominent immune response that requires ongoing presence of organisms. Pathophysiology of peripheral nerve involvement is not well established although it similarly requires the presence of viable organisms. Future work should focus on the mechanisms of tissue injury. Regardless of the presentation, infection is highly responsive to antimicrobial therapy. Relapsing fever is another human borreliosis caused by a variety of Borrelia species and transmitted by lice (epidemic form) or ticks (endemic form). Both are characterized by recurrent spirochetemia and can cause neurological complications similar to Lyme neuroborreliosis. Diagnosis is made by the direct observation of the spirochetes in peripheral blood during febrile episodes and by PCR. Tetracycline therapy is used.