Lyme disease in Western Europe: an emerging problem? A systematic review.

Objectives: Lyme borreliosis is the most common zoonotic disease in Europe and causes an estimated total burden of 10.55 disability-adjusted life years (DALY) per 100 000 population. Its incidence in Western Europe is assumed to be increasing, yet this remains to be confirmed. The aim of this study was to assess the emergence of Lyme disease in Western Europe by performing a systematic review of the scientific literature.Methods: Pubmed, Embase and grey literature were searched from database inception until August 2018 for articles reporting the incidence of Lyme borreliosis in Western European countries. We included observational studies in English that reported data on a random sample of the population and fulfilled our definition of Lyme disease diagnosis. Annual population-weighted averages and the evolution of Lyme borreliosis incidence were extracted or calculated for every Western European country.Results: Our review identified 1514 and included 18 studies next to seven surveillance reports reporting data from 16 Western European countries. Incidence of Lyme borreliosis ranged from 0.001 (Italy) to 632 (Sweden, Blekinge county) cases/100 000/year. Iceland reported the strongest emergence with an average yearly increase of 21.15% over a 12-year period, whereas Italy reported the strongest average yearly decrease of 52.71% over a 5-year period. Very limited high-quality data were available on Lyme borreliosis incidence in the southern Western European countries.Conclusion: Diagnosis of Lyme borreliosis is on the rise in some Western European countries, mostly in the northern and central part. Better surveillance in the southern countries is necessary.