Molecular-based laboratory testing confer accuracy over microscopical testing for tick identification

Area of Science:

• Veterinary Entomology
• Medical Entomology
• Molecular Diagnostics

Background:

• Ixodes pacificus is the primary Lyme disease vector in British Columbia (BC).
• Ixodes scapularis is the dominant Lyme disease vector on Canada's East Coast.
• A recent report indicated the presence of Ixodes scapularis in BC, prompting further investigation.

Purpose of the Study:

• To assess the accuracy of microscopic tick identification at the BC Centre for Disease Control (BCCDC) Public Health Laboratory.
• To compare morphologic identification methods with molecular identification techniques.
• To determine the prevalence and origin of Ixodes scapularis ticks in BC.

Main Methods:

• Microscopic identification of 209 ticks received by the BCCDC Public Health Laboratory.
• Molecular identification using real-time PCR for Ixodes scapularis screening (ITS2 region).
• Species confirmation via Sanger sequencing of the cytochrome c oxidase subunit 1 gene.

Main Results:

• Ixodes pacificus comprised 74% of identified ticks; Ixodes scapularis accounted for 3.8%.
• Molecular methods confirmed microscopic identification accuracy.
• Six of eight Ixodes scapularis hosts had recent travel history outside BC.

Conclusions:

• Ixodes pacificus remains the dominant tick species in British Columbia.
• Identified Ixodes scapularis ticks in BC are likely associated with host travel.
• Enhanced tick surveillance is crucial due to facilitated tick migration via global travel.