The trans-Atlantic movement of the spirochete Borrelia garinii

The spirochete Borrelia garinii, one of three genospecies of B. burgdorferi sensu Jato (B. burdorferi s.l.) that can cause Lyme disease in humans, has recently been isolated from seabirds from a colony in Newfoundland, Canada. Previous records of B. garinii in seabirds suggest that it has been endemic in seabird colonies in the greater North Atlantic since at least the early 1990s. We determined the prevalence of B. gari­nii in different seabird hosts from colonies in the northwest Atlantic. We recorded B. gari­nii from Gannet Islands, Labrador. and Gull Island, Newfoundland, Canada, in Atlantic Puffins (Fratercula arctica), Herring Gulls (Larus argentatus), Common Murres (Uria aalge), and Razorbills (Alca torda).

Prevalence of infections varied between years and within and among species. Ticks from Atlantic Puffins had a prevalence ranging from 10.3 to 36.4%, although the highest prevalence was noted in Herring Gulls (37.5%) in 2005. Earlier studies from the same localities failed to find evidence of B. garinii, suggesting a recent arrival of the spirochete into the northwest Atlantic. B. garinii is closely related to European strains of the spirochete, and its likely source is from areas of endemicity in the Bothnian Gulf and the northeast Atlantic seabird colonies where seabirds, songbirds, and two different tick species come in close proximity.

Phylogenetic studies suggest a gradual movement of the European strains into seabird colonies in the northeast Atlantic with subsequent spread into the North and northwest Atlantic colonies. Atlantic Puffins seem to be suitable reservoirs, although other abundant species such as Common Murres and Thick-billed Murres (Uria lomvia) may be involved in B. garinii dynamics. Further work is urgently needed to help document the ecology and spread of this spirochete of importance to human health.