A multisystemic disorder, Lyme disease is caused by the spirochete Borrelia burgdorferi, which is carried by Ixodes dammini, I. Pacificus, and other ticks in the Ixodidae family. It commonly begins in the summer with a papule that becomes red and warm but isn’t painful. This classic skin lesion is called erythema chronicum migrans (ECM), which may be confused with a similar rash caused by Southern tick-associated rash illness. (See Southern tick-associated rash illness, page 208.). Weeks or months later, cardiac or neurologic abnormalities sometimes develop, possibly followed by arthritis of the large joints.
Lyme disease occurs when a tick injects spirochete-laden saliva into the bloodstream. After incubating for 3 to 32 days, the spirochetes migrate out to the skin, causing ECM. Then they disseminate to other skin sites or organs via the bloodstream or lymph system. They may survive for years in the joints, or they may trigger an inflammatory response in the host and then die.
Initially, Lyme disease was identified in a group of children in Lyme, Connecticut. Now it's known to occur primarily in three parts of the United States: in the northeast, from Massachusetts to Maryland; in the Midwest, in Wisconsin and Minnesota; and in the west, in California and Oregon. Although it's endemic to these areas, cases have been reported in all 50 states and in 20 other countries, including Germany, Switzerland, France, and Australia.
Typically, Lyme disease has three stages. ECM heralds stage one with a red macule or papule, commonly at the site of a tick bite. This lesion typically feels hot and itchy and may grow to over 20" (50.8 cm) in diameter; it resembles a bull’s eye or target. Within a few days, more lesions may erupt, and a migratory, ringlike rash, conjunctivitis, or diffuse urticaria occurs. In 3 to 4 weeks, lesions are replaced by small red blotches, which persist for several more weeks. Malaise and fatigue are constant, but other findings are intermittent: headache, neck stiffness, fever, chills, achiness, and regional lymphadenopathy. Less common effects are meningeal irritation, mild encephalopathy, migrating musculoskeletal pain, hepatitis, and splenomegaly. A persistent sore throat and dry cough may appear several days before ECM.
Weeks to months later, the second stage (disseminated infection) begins, and patients may develop additional symptoms depending on the system affected. Neurologic abnormalities — fluctuating meningoencephalitis with peripheral and cranial neuropathy — usually resolve after days or months. Facial palsy is especially noticeable. Cardiac abnormalities, such as a brief, fluctuating atrioventricular heart block, left ventricular dysfunction, or cardiomegaly may also develop. Cardiac involvement lasts only a few weeks but can be fatal.
Stage three (persistent infection) usually begins weeks or years later and is characterized by arthritis in about 80% of patients. Migrating musculoskeletal pain leads to frank arthritis with marked swelling, especially in the large joints. Recurrent attacks may precede chronic arthritis with severe cartilage and bone erosion.
Because isolation of B. burgdorferi is difficult in humans and serologic testing isn’t standardized, diagnosis is usually based on the characteristic ECM lesion and related clinical findings, especially in endemic areas. Antibodies to B. burgdorferi are indentified by immunofluorescence or enzyme-linked immunosorbent assay (ELISA). ELISAs are confirmed with Western blot tests. Mild anemia and an elevated erythrocyte sedimentation rate, leukocyte count, serum immunoglobulin M, and aspartate aminotransferase levels support the diagnosis.
Clinicians must differentiate between Lyme disease and arthritis, encephalopathy, or polyneuropathy.
A 28-day course of an antibiotic, such as doxycycline, is the treatment of choice for nonpregnant adults. Oral penicillin is usually prescribed for children. Alternatives include tetracycline, cefuroxime, and ceftriaxone. When given in the early stages, these drugs can minimize later complications. When given during the late stages, high-dose I.V. ceftriaxone may be successful.
❑Take a detailed patient history, asking about travel to endemic areas and exposure to ticks.
❑Check for drug allergies, and administer antibiotics carefully.
❑For a patient with arthritis, help with range-of-motion and strengthening exercises, but avoid overexertion. Ibuprofen helps relieve joint stiffness.
❑Assess the patient's neurologic function and level of consciousness frequently. Watch for signs of increased intracranial pressure and cranial nerve involvement, such as ptosis, strabismus, and diplopia. Also check for cardiac abnormalities, such as arrhythmias and heart block.
Review other book chapters online related to Lyme disease:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
|
More About This Book:
Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X 
|
|
What do you think about the features of this website? Take our user survey and have your say:
Next articles:
Tools & Services:
Medical Articles:
Search Specialists by State and City
By using this site you agree to our Terms of Use. Information provided on this site is for informational purposes only; it is not intended as a substitute for advice from your own medical team. The information on this site is not to be used for diagnosing or treating any health concerns you may have - please contact your physician or health care professional for all your medical needs. Please see our Terms of Use.
Copyright © 2009 Health Grades Inc. All rights reserved.
