Fig. 2.

Lyme borreliosis cases in Hilmo that were not microbiologically confirmed in 2014. 314 additional cases could be extracted from NIDR when the linkage-time was relaxed to the 2004–2015 period. These include Hilmo entries where microbiological testing for LB was performed years earlier than 2014 but where the diagnoses were repeated in subsequent hospital visits without a suspicion of a new infection (“old LB notifications in Hilmo”), and Hilmo entries where microbiological testing was performed either just at the end of 2013 or at the beginning of 2015 i.e. hospital cases that truly represent new LB infections in 2014. Patient records of two major hospital districts, Varsinais-Suomi HD and Helsinki and Uusimaa HD, representing 57.8% of microbiologically unconfirmed hospital cases in 2014, were reviewed. EM = Erythema migrans, Hilmo = National Hospital Discharge Register, LB = Lyme Borreliosis, NIDR = National Infectious Diseases Register