Monitoring of ticks and tick-borne pathogens through a nationwide research station network in Finland

Satu Mäkelä,Ella‐Maria Vesilahti ,Martin Snickars,Tommi Andersson,Katja Mäkinen,H Halonen ,Antti Uotila,John Loehr,Janne Sundell,Noora Haavisto,Maija Laaksonen,Jani J. Sormunen,Jari Hänninen,Jouni Aspi,Jari Ylönen,Riku Paavola,Jaana Bäck,Tero Klemola,Ella Sippola,Hannu Ylönen,Pauliina Pajala,Eero J. Vesterinen,Joanna Norkko,Tony Cederberg,Silja Vuorenmaa,Jasmin Inkinen,Anna I. E. Puisto ,Niko Kulha,Niko Tanski,Tuukka Petäj̈ä

doi:10.1016/j.ttbdis.2020.101449

Abstract

In 2015 a long-term, nationwide tick and tick-borne pathogen (TBP) monitoring project was started by the Finnish Tick Project and the Finnish Research Station network (RESTAT), with the goal of producing temporally and geographically extensive data regarding exophilic ticks in Finland. In the current study, we present results from the first four years of this collaboration.Ticks were collected by cloth dragging from 11 research stations across Finland in May–September 2015–2018 (2012–2018 in Seili). Collected ticks were screened for twelve different pathogens by qPCR: Borrelia afzelii, Borrelia garinii, Borrelia valaisiana, Borrelia burgdorferi sensu stricto, Borrelia miyamotoi, Babesia spp., Anaplasma phagocytophilum, Rickettsia spp., Candidatus Neoehrlichia mikurensis, Francisella tularensis, Bartonella spp. and tick-borne encephalitis virus (TBEV).Altogether 15 067 Ixodes ricinus and 46 Ixodes persulcatus were collected during 68 km of dragging. Field collections revealed different seasonal activity patterns for the two species. The activity of I. persulcatus adults (only one nymph detected) was unimodal, with activity only in May–July, whereas Ixodes ricinus was active from May to September, with activity peaks in September (nymphs) or July–August (adults). Overall, tick densities were higher during the latter years of the study. Borrelia burgdorferi sensu lato were the most common pathogens detected, with 48.9 ± 8.4% (95% Cl) of adults and 25.3 ± 4.4% of nymphs carrying the bacteria. No samples positive for F. tularensis, Bartonella or TBEV were detected.This collaboration project involving the extensive Finnish Research Station network has ensured enduring and spatially extensive, long-term tick data collection to the foreseeable future.

Highlights

Ticks and tick-borne pathogens (TBPs) constitute a growing threat to public health in Europe
As there appears to be little that can realistically be done to cull tick populations using existing methodology (Beaujean et al, 2016; Ostfeld et al, 2006; Stafford III et al, 2017; Van Buskirk and Ostfeld, 1995), increasing citizens’ awareness regarding ticks and tick-borne pathogens is important in preventing tick-borne diseases (TBDs) (Beaujean et al, 2016; Butler et al, 2016; Zöldi et al, 2017)
We introduce the nationwide, long-term sampling scheme organized by the Finnish Tick Project and Finnish research stations (RESTAT; www.researchstations.fi)

Summary

Introduction

Ticks and tick-borne pathogens (TBPs) constitute a growing threat to public health in Europe. Differences in abundance or activity may occur especially between far-apart areas, as ticks face different environments and host animal populations These differences, in all likelihood, affect local tick bite risk (the chance to get infected by a TBD) and its seasonal patterns, highlighting the importance of localized knowledge regarding ticks. In order to be able to accurately predict future changes in tick bite risk, long-term data of tick and TBP populations are needed (Bugmyrin et al, 2019) Such longitudinal data has far largely been missing from Finland, where few tickrelated studies have been conducted prior to the current decade (Sormunen, 2018)

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