Lyme borreliosis or Lyme disease

Lyme borreliosis (LB) or Lyme disease is caused by the spirochete, Borrelia burgdorferi, which is transmitted through the bite of an infected adult tick or nymph. Ixodes scapularis, also known as the deer tick, is the most common vector for Lyme disease in North America.

Lyme disease usually manifests itself as a localized infection of the skin (erythema migrans), followed by multiple spirochete reactions on the skin and body parts such as the heart, joints and nervous system. The disease is divided into three stages. The first stage, or acute illness, occurs at the site of the tick bite and results in the development of a skin lesion as the Borreliae multiply and spread into the dermis layer of the skin.

The usual systemic symptoms of the first stage include headaches, fever, myalgia, and arthralgia. In the second, or the dissemination phase, the Borreliae spread hematogenously and cause secondary annular skin lesions, migratory arthritis, cardiac arrhythmias and meningitis. To fight off the infection, the body develops antibodies to the spirochete.

Finally, the late chronic phase develops if the disease remains untreated and may occur in some cases, up to two to three years after the initial infection and demonstrate clinical signs such as destructive chronic arthritis, acrodermatitis chronica atrophicans and neuropathy.

It is usually treated by a two to three week course of antibiotics which include oral courses of doxycycline or amoxicillin. In patients whose disease has progressed, treatment entails a four week course of oral medication or a two to four week course of IV ceftriaxone if the patient does not respond to oral therapy.

Two vaccines have been developed to combat Lyme disease, particularly in endemic regions. These vaccines use recombinant B. burgdorferi lipidated outer-surface protein A (rOspA) as immunogen -- LYMErix and ImuLyme.

More details at Medscape