The Establishment of a Blacklegged Tick Population by Migratory Songbirds in Ontario, Canada

This 2-year study implicates migratory songbirds in the initiation of an inland Lyme disease endemic area in southeastern Ontario. The spirochetal bacterium, Borrelia burgdorferi sensu lato Johnson, Schmid, Hyde, Steigerwalt & Brenner, which causes Lyme disease, was detected in blacklegged ticks, Ixodes scapularis Say, collected by flagging. Based on PCR amplification, 19 (33.3%) of 57 I. scapularis adults (males, females) were infected with B. burgdorferi. Since transovarial transmission of B. burgdorferi is nil in I. scapularis and white-tailed deer. Odocoileus virginianus Zimmermann, are not reservoir-competent hosts, we suggest that songbirds are the mode of introduction of B. burgdorferi-infected I. scapularis. All of the natural abiotic and biotic attributes are present to establish a Lyme disease endemic area. Blacklegged ticks survived the winter successfully at the epicentre. We provide substantial evidence that migratory songbirds initially introduced Lyme disease vector ticks and B. burgdorferi spirochetes to this remote woodland habitat and initiated an established population of blacklegged ticks.