Lyme Disease

Key Features

Essentials of Diagnosis

• Erythema migrans, a flat or slightly raised red lesion that expands with central clearing

• Headache or stiff neck

• Arthralgias, arthritis, and myalgias; arthritis is often chronic and recurrent

• Wide geographic distribution, with most cases in the northeast, mid-Atlantic, upper midwest, and Pacific coastal regions of the United States

General Considerations

• Causative spirochete varies by geography

  • In the United States, it is Borrelia burgdorferi senu strictu

  • In Europe and Asia, it is Borrelia garinii and Borrelia afzelli

• Incidence of disease is significantly higher when tick attachment is for longer than 72 h

• The percentage of ticks infected varies on a regional basis. In the northeast and midwest, 15–65%, in the west, < 5%

• Congenital infection has been documented

• Ixodes scapularis is capable of transmitting other infections in addition to Lyme disease, including babesiosis and human granulocytic anaplasmosis (formerly human granulocytic ehrlichiosis)

  • Coinfection with two or even all three of these organisms can occur, causing a clinical picture that is not "classic" for any of these diseases

  • Coinfection should be considered and excluded in patients who have

    • Persistent high fevers 48 hours after starting appropriate therapy for Lyme disease

    • Persistent symptoms despite resolution of rash

    • Anemia, leukopenia, or thrombocytopenia

Demographics

• Most cases are reported from the mid-Atlantic, northeastern, and north central regions of the country

• True incidence is unknown and overreporting continues to be a problem for following reasons:

  • Serologic tests are not standardized

  • Clinical manifestations are nonspecific

  • Serology tests are insensitive in early disease

• Most infections occur in the spring and summer

Clinical Findings

Symptoms and Signs

• Stage 1, early localized infection

  • Erythema migrans

    • A flat or slightly raised red lesion at the bite site ~1 week after the tick bite (range, 3–30 days; median, 7–10 days)

    • Common in areas of tight clothing such as the groin, thigh, or axilla

    • The lesion expands over several days

    • Classic lesion progresses with central clearing ("bulls-eye" lesion); often there is a more homogeneous appearance or even central intensification

  • Concomitant viral-like illness develops in most patients and is characterized by

    • Myalgias, arthralgias

    • Headache, fatigue

    • Fever may or may not be present

• Stage 2, early disseminated infection (weeks to months later)

  • Bacteremia (in up to 50–60% of patients with erythema migrans)

  • Secondary skin lesions

    • Develop within days to weeks of original infection in about 50% of patients

    • Lesions similar to primary lesion but smaller

    • Skin involvement can be manifested as a cutaneous hypopigmented lesion called a borrelial lymphocytoma (rare)

  • Malaise, fatigue, fever, headache, neck pain generalized achiness common with skin lesions

  • Myopericarditis, with atrial or ventricular arrhythmias and heart block (4–10%)

  • Neurologic manifestations (10–15%)

    • Aseptic meningitis with mild headache and neck stiffness

    • Cranial nerve VII ...