Update on the presence of Ixodes ricinus at the western limit of its range and the prevalence of Borrelia burgdorferi sensu lato.

It is often suggested that due to climate and environmental policy changes, the risk from tick-borne disease is increasing, particularly at the geographical limits of the vector distribution. Our project aimed to determine whether this was true for the risk of Lyme borreliosis in Ireland which is the western-most limit of Ixodes ricinus, the European vector of Borrelia burgdorferi sensu lato. The availability of a historical data set of tick infection rates compiled in the 1990s represented a unique opportunity as it provided a baseline against which current data could be compared.