Lyme disease

Lyme disease (Borreliosis) is a bacterial infection with a spirochete from the species complex Borrelia burgdorferi, which is most often acquired from the bite of an infected Ixodes, or black-legged, tick, also known as a deer tick. The deer tick is not the only carrier of this disease. The deer tick is frequently mistaken for a dog tick which is more common and larger in size. Borrelia burgdorferi sensu stricto is the predominant cause of Lyme disease in the U.S.; Lyme disease in Europe is more often caused by Borrelia afzelii or Borrelia garinii.

The disease varies widely in its presentation, which may include a rash and flu-like symptoms in its initial stage, followed by the possibility of musculoskeletal, arthritic, neurologic, psychiatric and cardiac manifestations. In most cases of Lyme disease, symptoms can be eliminated with antibiotics, especially if treatment is begun early in the course of illness.

A percentage of patients with Lyme disease have symptoms that last months to years after treatment with antibiotics. These symptoms can include muscle and joint pains, arthritis, stiff neck, cognitive defects, neurological complaints or fatigue. The cause of these continuing symptoms is not yet known. There is some evidence that they may result from an autoimmune type of response, in which a person’s immune system continues to respond even after the infection has been cleared, as well as evidence of ongoing infection with the spirochete.

Delayed or inadequate treatment may often lead to "late stage" Lyme disease that is disabling and difficult to treat. Amid great controversy over diagnosis, testing and treatment, two different standards of care for Lyme disease have emerged.