Crowdsourcing-based nationwide tick collection reveals the distribution of Ixodes ricinus and I. persulcatus and associated pathogens in Finland

Abstract

A national crowdsourcing-based tick collection campaign was organized in 2015 with the objective of producing novel data on tick distribution and tick-borne pathogens in Finland. Nearly 20 000 <em>Ixodes</em> ticks were collected. The collected material revealed the nationwide distribution of <em>I. persulcatus</em> for the first time and a shift northwards in the distribution of <em>I. ricinus</em> in Finland. A subset of 2038 tick samples containing both species was screened for <em>Borrelia burgdorferi</em> sensu lato (the prevalence was 14.2% for <em>I. ricinus</em> and 19.8% for <em>I. persulcatus</em>), <em>B. miyamotoi</em> (0.2% and 0.4%, respectively) and tick-borne encephalitis virus (TBEV; 0.2% and 3.0%, respectively). We also report new risk areas for TBEV in Finland and, for the first time, the presence of <em>B. miyamotoi</em> in ticks from mainland Finland. Most importantly, our study demonstrates the overwhelming power of citizen science in accomplishing a collection effort that would have been impossible with the scientific community alone.