Evidence for Borrelia bavariensis Infections of Ixodes uriae within Seabird Colonies of the North Atlantic Ocean.

The first report of members of the spirochete genus in the seabird tick, , and seabird colonies occurred during the early 1990s. Since then, spp. have been detected in these ticks and seabird colonies around the world. To date, the primary species detected has been , with rare occurrences of and During our research on and in seabird colonies of Newfoundland and Labrador, Canada, we have identified in To our knowledge, has previously been found only in the Eurasian tick species and , and it was believed to be a rodent-specific ecotype. We found within from three seabird colonies over three calendar years. We also reanalyzed sequences collected from from Eurasian seabird colonies and determined that sequences from two Russian seabird colonies likely also represent The Canadian sequences from analyzed in this study cluster with previously described sequences from Asia. Overall, this is an important discovery that illustrates and expands the range of hosts and vectors for , and it raises questions regarding the possible mechanisms of pathogen dispersal from Asia to North America. To our knowledge, this is the first documentation of outside Eurasia. Additionally, the bacterium was found in a marine ecosystem involving the seabird tick and its associated seabird hosts. This indicates that the epizootiology of transmission is much different from what had been described, with this species previously believed to be a rodent-specific ecotype, and it indicates that this pathogen is established, or establishing, much more widely.