Lyme disease is on the rise in Canada. In 2009, Canada saw only 144 reported cases, which surged to 3,147 by 2021, and analysis suggests the trend will continue with climate change. Here’s what to know as the tick season approaches.
Understanding Tick-Borne Diseases in Canada
Tick-borne diseases develop after a patient contracts a viral, bacterial, or parasitic infection from an infected tick. There are a few diseases that affect humans, each caused by a different organism, including:
- Anaplasmosis
- Babesiosis
- Tick-borne relapsing fever
- Lyme-like disease
- Lyme disease
Lyme disease is the most reported tick-borne disease in North America and affects 7.7 people for every 100,000 in Canada alone.
Educating Patients on Prevention
Any tick can carry infections that cause disease, and patients may not know they’re exposed. The best way to avoid disease is to prevent bites. Advise patients to:
- Avoid tick-infested areas, especially leafy areas and long grass
- Wear long pants and sleeves in tick areas
- Tuck pants into socks
- Wear close-toed shoes
- Use repellent on skin, shoes, and clothes
Recognizing Symptoms and Risk Factors
Patients may experience Lyme disease symptoms early on, within three to 30 days of a tick bite, known as early localized disease. It usually presents as an acute illness with symptoms such as:
- Fever
- Muscle pain
- Headache
- Fatigue
- Migratory joint pain
- Swollen lymph nodes
- Red rash called erythema migrans or bull’s eye rash
Disease Stages and Symptoms
The remaining stages are known as early disseminated disease and late disease. Early disseminated disease develops within less than three months of a bite as bacteria spread to other organs and tissues.
Early disseminated disease causes:
- Erythema migrans rash: An erythema migrans rash expands to greater than 5 cm in diameter at the site of the tick bite.
- Fatigue
- Weakness
- Joint and muscle pain
- Aseptic meningitis
- Encephalitis
- Cranial neuropathy
- Radiculitis
- Conjunctivitis
- Carditis heart block
Late disease occurs three months or more after a bite and can last for months or years. It usually advances when patients don’t know they’ve been bitten and infected or haven’t received suitable treatment. Symptoms are similar to early disseminated disease but may be more pronounced and widespread. Possible manifestations can include:
Musculoskeletal:
- Baker’s cyst
- intermittent episodes of pain and/or swelling in one or multiple joints, particularly the knees and other large joints leading to chronic arthritis
- if untreated, arthritis may recur in the same or different joints
Neurological and cognitive:
- meningitis
- meningoencephalitis
- subacute mild encephalopathy, affecting:
- memory
- concentration
- myelitis
- cranial neuropathy
- radiculopathy
- chronic mild axonal polyneuropathy, manifested as:
- distal paresthesia
- radicular pain (less common)
Rare forms of presentation include:
- encephalomyelitis
- leukoencephalopathy
- diaphragmatic paralysis caused by phrenic nerve palsy leading to tick-induced respiratory paralysis or respiratory distress
Diagnostic Approaches
Lyme disease diagnosis occurs through clinical presentation and examination of a history of exposure to ticks and clinical signs and symptoms. However, patients may present with generalized symptoms without noticing the hallmark bull’s eye rash. In these cases, order additional testing to confirm.
Laboratory Confirmation
Lyme disease testing in Canada follows a two-tiered approach. Start with an enzyme immunoassay (EIA) to identify antibodies to Borrelia burgdorferi. If the result is positive or equivocal, follow up with confirmatory immunoblots, such as the western blot, IgG, or IgM immunoblots.
Treatment Strategies
Antibiotics, specifically doxycycline, cefuroxime axetil and amoxicillin are the most commonly recommended first-line treatment for Lyme disease, however doxycycline is not recommended for pregnant people. Oral antibiotics are most effective in the early stages. Late disease may require intravenous antibiotics for several months. Patients who can’t tolerate antibiotics may benefit from intramuscular versions, which release slowly.
Post-Exposure Prophylaxis (PEP) and Referrals
Patients who can confirm specific criteria following a tick may qualify for preventive treatment with a single dose of doxycycline. The criteria include:
- Verified black-legged tick
- Attached for 24 hours or more and engorged
- Tick was from a known infested area
- Treatment can start with 72 hours of a bite
It is not 100 percent effective, so patients should watch for symptoms for 30 days. Refer back to their primary physician for follow-up.
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