A multisystemic disorder, Lyme disease is caused by the spirochete Borrelia burgdorferi, which is carried by the minute tick Ixodes dammini or another tick in the Ixodidae family. It typically begins in summer, with the classic skin lesion called erythema chronicum migrans (ECM). Weeks or months later, cardiac or neurologic abnormalities sometimes develop, possibly followed by arthritis.
Lyme disease occurs primarily in areas of the United States inhabited by the deer tick, such as:
❑ in the northeast, from Massachusetts to Maryland
❑ in the midwest, in Wisconsin and Minnesota
❑ in the west, in California and Oregon.
Although Lyme disease is endemic to these areas, cases have been reported in 43 states and 20 other countries, including Germany, Switzerland, France, and Australia.
Lyme disease occurs when a tick injects spirochete-laden saliva into the bloodstream or deposits fecal matter on the skin. 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 by the bloodstream or lymph system.
The spirochetes’ life cycle isn’t completely clear: They may survive for years in the joints or they may trigger an inflammatory response in the host and then die.
Typically, Lyme disease has three stages.
ECM heralds stage 1 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 more than 20" (50 cm) in diameter. Within a few days, more lesions may erupt along with a malar rash, conjunctivitis, or diffuse urticaria. 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 signs and symptoms are intermittent: headache, fever, chills, achiness, and regional lymphadenopathy. Less common findings are meningeal irritation, mild encephalopathy, migrating musculoskeletal pain, and hepatitis. A persistent sore throat and dry cough may appear several days before ECM.
Weeks to months later, the second stage begins with neurologic abnormalities — fluctuating meningoencephalitis with peripheral and cranial neuropathy — that usually resolve after days or months. Facial palsy is especially noticeable. Cardiac abnormalities, such as a brief, fluctuating atrioventricular heart block, may also develop.
Characterized by arthritis, stage 3 begins weeks or years later. 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 unusual in humans and because indirect immunofluorescent antibody tests are marginally sensitive, diagnosis usually rests on the characteristic ECM lesion and related signs and symptoms, especially in endemic areas. Mild anemia and an elevated erythrocyte sedimentation rate, leukocyte count, serum immunoglobulin M level, and aspartate aminotransferase level support the diagnosis.
A 3- to 4-week course of antibiotic treatment using doxicycline or amoxicillin is generally effective in early disease. Cefuroxime axetil and erythromycin are alternatives. Oral penicillin is usually prescribed for children. When given in the early stages, these drugs can minimize later complications. When given during the late stages, high-dose I.V. penicillin or I.V. ceftriaxone may be a successful treatment.
CLINICAL TIP: Neurologic abnormalities are best treated with I.V. ceftriaxone or I.V. penicillin.
❑ Take a detailed patient history, asking about travel to endemic areas and exposure to ticks.
❑ Check for drug allergies, and carefully administer the prescribed antibiotic.
❑ For a patient with arthritis, help with range-of-motion and strengthening exercises, but avoid overexertion.
❑ 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.
❑ 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.
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More About This Book:
Title: Handbook of Diseases Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2003 ISBN: 1-58255-266-5 
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