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 will be used to calculate the mean incidence. The mean incidence rates will then be combined to estimate the regional burden and a population-weighted regional burden of disease based on the standardized incidence rate from the included studies and the total population at risk. Methods: Reviews and surveillance reports identified by the initial database search were assessed for eligibility first by their title and abstract and subsequently by a more detailed review of the source by two independent authors for the most recent data regarding LB. Eleven 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 464/100 000 and the lowest in Italy of 0.001/100 000. The unweighted mean for the included data provided an incidence rate of 56.3/100 000 persons per year, equating to ∼232 125 cases in 1 year throughout the region. The calculated population-weighted average incidence rate for the regional burden of LB in Western Europe was 22.05 cases per 100 000 person-years. Conclusions: LB is a continually emerging disease and the most common zoonotic infection in Western Europe approaching endemic proportions in many European countries. The population-weighted incidence rate has been estimated by this study to be 22.04/100 000 person-years. Concordant and well-conducted surveillance and disease awareness should continue to be encouraged to monitor LB, as tick numbers and activity are increasing, leading to greater risks of infection