First isolation and characterisation of Borrelia garinii, agent of Lyme borreliosis, from Irish ticks.

Nymphal Ixodes ricinus, the tick vector of Lyme borreliosis, were collected from the edges of paths in Muckross Demesne, Killarney National Park, Co. Kerry, Ireland. Examination of some of these nymphs by indirect immunofluorescence showed an infection prevalence of 12% with Borrelia burgdorferi sensu lato, the spirochaete agent of Lyme borreliosis. Gerbils (Meriones unguiculatus) were infected by infesting them with other nymphs from the same batch. Subsequently uninfected laboratory larvae were applied to the gerbils and the contents of the resulting infected engorged ticks were then placed in media and the spirochaetes cultured. The spirochaetes were identified as B. burgdorferi sensu lato by indirect immunofluorescence using monoclonal antibodies and they were further characterised by polymerase chain reaction and pulsed-field gel electrophoresis. Both of these latter techniques showed that spirochaetes in all samples belonged to the genomic species, Borrelia garinii.