Tick distribution and tick-borne pathogens in Finland - The tick project of the University of Turku

Abstract

Ticks and tick-borne diseases are a growing problem in northern Europe and Russia. Surveys conducted in Russia, Sweden and Norway have revealed a northwards shift in distribution and an increase in tick abundance over the past few decades. However, despite ticks being actively studied in neighboring countries, ecological data of Finnish tick populations are almost non-existent. Furthermore, the last nationwide mapping of the geographical distribution of Ixodes ricinus in Finland is over five decades old. Regarding the distribution of the taiga tick (Ixodes persulcatus), no nationwide surveys have ever been made. The University of Turku tick project was started in 2012 with the objective of producing novel data on tick abundance, ecology and tick-borne pathogen diversity in Finland. Initially the main aim of the project was to revisit several study locations around Southwest Finland from where previous ecological and Borrelia burgdorferi sensu lato prevalence data was available. Blanket dragging was conducted at these locations, to survey possible changes in tick abundance and B. burgdorferi s.l. prevalence. Additional blanket dragging locations were added around southwestern Finland later in 2013-2014. In addition to B. burgdorferi s.l., the occurrence and prevalence of several other tick-borne pathogens has also been determined from these samples. Furthermore, a long-term surveillance site for tracking annual changes in tick abundance, seasonal questing activity patterns and pathogen diversity was established in 2012 on one of the study locations, Seili. Similar surveillance sites were established in 2015 at several university research stations all around Finland. However, in addition to these local data of tick abundance, activity patterns and pathogen diversity, the project also wanted to produce nationwide data on the geographical distribution of the two currently known disease-transmitting tick species in Finland, I. ricinus and I. persulcatus. To accomplish this, we decided to try a crowdsourcing approach: in 2014 we launched a national questionnaire survey on the internet, asking citizens to report their tick sightings via coordinates. We received nearly 4400 answers to the questionnaire and subsequently released a map visualizing the coordinate points given in those answers (www.puutiaiset.fi). Inspired by the success of this questionnaire, we organized a national tick collection campaign in 2015, where we asked citizens to send ticks to us at the University of Turku. The collection campaign was a success, with nearly 7000 letters delivered to the university. These letters contained approximately 20 000 individual ticks from all around Finland. The results of our field studies suggest that both tick abundance and B. burgdorferi s.l. prevalence have increased in Southwest Finland between the twelve years separating the two studies conducted there. In addition to B. burgdorferi s.l., Borrelia miyamotoi, Rickettsia helvetica and Rickettsia monacensis have been detected from collected ticks. Borrelia miyamotoi, R. helvetica and R. monacensis have also been detected from larval tick samples. Currently we are working on the massive data gathered in the national collection campaign. While laboratory analyses have only just been started, identification and mapping of the received tick samples has already revealed that I. persulcatus is much more prevalent in Finland than previously thought. Furthermore, with the coordinate data from both the questionnaire survey and tick collection campaign, we have been able to accurately map the geographical distributions of both I. ricinus and I. persulcatus in Finland.

Published in

Publisher: University of Turku

Conference

NordTick 2016

SLU Authors

• Vesterinen, Eero

  • University of Helsinki
  • University of Turku

UKÄ Subject classification

Ecology

Permanent link to this page (URI)

https://res.slu.se/id/publ/107900