Lyme Disease is the Most Common Tick-Borne Illness in Nova Scotia
Lyme disease, caused by Borrelia burgdorferi and transmitted by Ixodes scapularis (blacklegged) ticks, is definitively the most common tick-borne illness in Nova Scotia. 1, 2
Epidemiological Evidence from Nova Scotia
The data from Nova Scotia is unequivocal:
- Nova Scotia has the highest Lyme disease incidence in Canada, reaching 16 cases per 100,000 population in 2013 1
- From 2002-2013,329 confirmed Lyme disease cases were reported, with incidence rising sharply over this period 1
- More recent data (2018-2023) shows continued dramatic increases, with 4,238 confirmed cases under current case definitions 2
- Seroprevalence increased from 0.14% (2/1855) a decade ago to 1.60% (25/1872) in recent surveys, representing more than a 10-fold increase 3
Clinical Presentation in Nova Scotia Patients
The typical presentation in Nova Scotia includes:
- 89.7% report early localized infection with rash
- 69.6% experience influenza-like illness
- 53.2% have clinician-documented erythema migrans 1
This predominantly early-stage presentation pattern is important for clinical recognition.
Geographic Distribution
Risk is not uniform across Nova Scotia:
- Ixodes scapularis ticks are endemic to at least 6 regions 1
- The Western Zone consistently reports the highest incidence rates 2
- Risk remains localized to currently identified endemic regions 1
Seasonal Pattern
Cases peak from June to September, with reporting peaks occurring during these warmer months 2. This aligns with the nymphal tick feeding season when transmission risk is highest.
Other Tick-Borne Pathogens Present
While Lyme disease dominates, surveillance has identified other pathogens in Nova Scotia ticks including Anaplasma phagocytophilum, Borrelia miyamotoi, Babesia microti, Babesia odocoilei, and Powassan virus 4. However, these remain far less common than Lyme disease in clinical practice.
Diagnostic Approach
For patients with suspected Lyme disease in Nova Scotia:
- Erythema migrans (≥5 cm expanding annular lesion) in an endemic area requires no laboratory testing - treat immediately 5, 6
- For all other presentations, use two-tiered serologic testing: EIA/IFA followed by reflex Western blot 5
- Sensitivity is only 30-40% during early infection (first 2-3 weeks) but increases to 70-100% for disseminated disease 5
- Specificity remains high (>95%) throughout all stages 5
Treatment Recommendation
Doxycycline is the drug of choice for confirmed or presumptive Lyme disease in both adults and children 7. This is critical because in regions where both Lyme disease and anaplasmosis occur (as in Nova Scotia), doxycycline covers both pathogens, whereas amoxicillin (sometimes used for Lyme) has no activity against Anaplasma 7.
Common Pitfall
The most significant clinical pitfall is delaying treatment while awaiting serologic confirmation during early infection. Given the low sensitivity of testing in the first weeks and the rising incidence in Nova Scotia, clinicians should treat empirically when clinical suspicion is high, particularly during tick season (June-September) in endemic regions 7, 5.