An Estimate of Lyme Borreliosis Incidence in Western Europe

Background: Lyme borreliosis (LB) is the most common zoonotic disease transmitted by ticks in the USA and Europe. This review aims to estimate the regional burden of LB in Western Europe. Data from previous publications were used to calculate the mean incidence. The mean incidence rates were then combined to estimate the regional burden and a population-weighted regional burden of disease based on the standardized incidence from the included studies and the total population at risk.Methods: Reviews and surveillance reports identified by the initial database search were first assessed for eligibility by their title and abstract, and subsequently by a more detailed review of the source for the most recent data regarding LB. 11 sources of incidence data were included in the review, representing 17 countries in total. Incidence estimates were calculated from reported values and population data.Results: Countries in Western Europe have a large variance in the incidence rates. The highest reported incidences for LB were reported in southern Sweden with 464 per 100 000 and the lowest in Italy of 0.001 per 100 000. The unweighted mean for the included data provided an incidence of 56.3 per 100 000 persons per year, equating to approximately 232 125 cases in one year throughout the region. The calculated population-weighted average incidence for the regional burden of LB in Western Europe was 22.05 cases per 100 000 person-years.Conclusions: LB is an emerging disease and the most common zoonotic infection in Western Europe approaching endemic proportions in many European countries. The population-weighted incidence has been estimated by this study to be 22.04 per 100 000 person-years. Concordant and well-conducted surveillance and disease awareness should continue to be encouraged to monitor LB as tick numbers and activity increases