Lyme Disease Guide.pdf

Lyme disease is the most common tick-borne infection in Canada, with a 1,000% increase in reported cases between 2009 and 2017.
The disease is caused by the bacteria B. burgdorferi, spread through bites from infected blacklegged ticks.
Early Lyme disease may be missed or misdiagnosed, allowing the bacteria to disseminate and cause serious illness.
Serologic testing has poor sensitivity for early Lyme disease.

Phases of Lyme Disease

Early Localized: 3-30 days after an infected tick bite, characterized by an erythema migrans (EM) rash and nonspecific symptoms.
Early Disseminated: 1-3 months after an infected tick bite, characterized by arthritis, cutaneous signs, neurologic manifestations, and cardiac symptoms.
Late Disseminated: > 3 months after an infected tick bite, characterized by arthritis and neuropathy.

Clinical Assessment

Step 1: Perform a full-body skin exam to determine if the patient has an EM rash.
Step 2: Identify nonspecific signs and symptoms consistent with early localized Lyme disease.
Step 3: Take a detailed patient history to determine if the patient could have been exposed to an infected tick.

EM Rash Characteristics

Appears 3-30 days after a tick bite
Expands within 48 hours of appearance, usually to >5 cm in diameter
May last for weeks if untreated
Often found near skin folds (underarm, groin, back of knee)

Nonspecific Signs and Symptoms

Subjective or objective fever
Generalized arthralgias and myalgias
Fatigue
Headache
Swollen lymph nodes

Patient History

Determine if the patient has been in areas where ticks are common (parks, meadows, wooded yards, etc.)
Ask about recent travel or outdoor activities
Consider the patient's pet history, as ticks can travel indoors on pets.