Lyme Borreliosis
Medical Profile
Borrelia burgdorferi is a fastidious microaerophilic spirochete, the causative bacterium for Lyme borreliosis. Three groups of Borrelia organisms have been cultured. They are collectively called Borrelia burgdorferi sensu lato. Group 1 (B. burgdorferi sensu stricta) is found in North America; Group 2 (B.garini) and Group 3 (B. afzeldi) are found in Europe and Asia.
The principle vectors are the ticks Ixodes scapularis in the Northeast, Ixodes pacificus in California and Oregon, Ixodes ricinus in Russia, China and Japan. I. Scapularis may transmit Babesia, Ehrlichia and Rickettsia.
Infectivity of the tick is carried out by the tiny nymph stage in the early summer months. The white-footed mouse is the host for the larva-nymph stage. The white tailed deer, not involved in the life cycle of the spirochete, is the preferred host for the adult Ixodes scapularis tick. Adult ticks occasionally transmit the spirochete to humans in the fall of the year.
Clinical manifestations: Stage 1, localized infection: After an incubation period 3 to 32 days, the initial lesion, erythema migrans (EM) is found at the site of the tick bite. This is an annular lesion with a red border and a central cleared area. Twenty five percent of patients are negative for this reacton. Stage 2, disseminated infection: After infection hematogenous spread with flu-like symptoms develop. Patients complain of headache, fever, chills, arthralgia, myalgia, malaise and fatigue. Cough and sore throat are prominent. Peripheral and central nervous system symptoms may develop after several weeks. Variable cardiac events may occur ranging from first degree A-V block of Wenckebach to complete heart block. Even myocarditis, pericarditis, and left ventricular dysfunction can occur. Musculoskeletal pain is common. Joint pain is usually without swelling. Stage 3, chronic infection: At this stage the joints are most commonly affected, especially the larger joints. Neurological changes, with memory loss, mood changes, and sleep disturbances are the most common symptoms. Severe myelitis (inflammation of the spinal cord) may also occur. A chronic course of neuro-borreliosis resembles the latent effects of another spirochete infection, tertiary neuro-syphilis.
The skin demonstrates acrodermatitis chronicum atrophicans.1,2
1. Steele A., Lyme borreliosis, Harrison’s Principles of Internal Medicine 15th edition, p1061-1064, McGraw-Hill, New York 2001
2. Mégard, F., van Loon F., & Thijens, S., Lyme disease, Infectious Diseases, p 8.19.9-11, Mosby, London, 1999
3. UpToDate © 2007