Lyme Disease Under-Detection in Canada: Why Cases Are Missed
Lyme disease may be significantly under-detected in Canada—far beyond previous estimates.
Researchers estimate that under-detection of Lyme disease in Canada exceeds the commonly cited 10-fold underreporting seen in the United States.
In one analysis from New Brunswick, only 1.7% to 8.3% of cases were identified—suggesting a 12- to 58-fold underestimation.
Why Lyme Disease Is Under-Detected
The authors identified several key reasons for under-detection:
- Failure to report clinically diagnosed Lyme disease
- Missed recognition of early symptoms by patients and clinicians
- Failure to include Lyme disease in the differential diagnosis
- Limited sensitivity of two-tiered serologic testing
For more, see Lyme disease test accuracy.
The Limits of Current Testing
The authors suggest that for every reported case, many more may go undiagnosed due to testing limitations.
Estimate: up to 30 additional cases may be missed for every confirmed diagnosis.
This highlights the challenges of relying on serologic testing alone to detect Lyme disease.
Public Health Impact
In 2016, 992 cases of Lyme disease were reported in Canada. However, the estimated true number ranged from 8,400 to over 56,000 cases.
Under-detection can lead to:
- Delayed diagnosis and treatment
- Inadequate healthcare resource allocation
- Increased long-term health and economic burden
Explore more on the impact of Lyme disease.
Clinical Perspective
Under-detection of Lyme disease reflects broader challenges in diagnosis, surveillance, and awareness.
Clinicians should consider Lyme disease even when testing is negative or symptoms are atypical.
Clinical Takeaway
Lyme disease is significantly under-detected in Canada, largely due to missed diagnoses and testing limitations.
References:
- Lloyd VK, Hawkins RG. Under-detection of Lyme disease in Canada. Healthcare (Basel). 2018.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
