Summary: | Borrelia garinii is the most neurotropic of the genospecies of B. burgdorferi sensu lato that cause Lyme disease in Europe, where it is transmitted to avian and mammalian reservoir hosts and to humans by Ixodes ricinus. B. garinii is also maintained in an enzootic cycle in seabirds by I. uriae, a tick found at high latitudes in both the Northern and Southern Hemispheres. To determine whether B. garinii is present in seabird ticks on the Atlantic Coast of North America, we examined 261 I. uriae ticks by polyclonal antiborrelial fluorescent antibody. Ten of 61 ticks from Gull Island, Newfoundland, were positive for borreliae by this screen. Amplicons of DNA obtained by PCR that targeted the B. garinii rrs-rrla intergenic spacer were sequenced and matched to GenBank sequences for B. garinii. The potential for introduction of this agent into the North American Lyme disease enzootic is unknown. In Europe, Lyme disease is caused by 3 genospecies of Borrelia burgdorferi (i.e., B. afzelii, B. garinii, B. burgdorferi sensu stricto), while in North America only B. burgdorferi sensu stricto, the genospecies present in I. scapularis ticks, has been implicated in human disease. B. garinii, the most neurotropic of these 3 genospecies, causes most neurologic Lyme disease in Europe, including cases of meningopolyneuritis and, rarely, encephalomyelitis (1–3). The presence of multiple pathogenic genospecies that cause Lyme disease in Europe complicates serodiagnostic testing (4). In Eurasia, B. garinii is transmitted to avian and rodent hosts and to humans by I. ricinus, the sheep or forest tick
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