Predicting habitat suitability for Ixodes ricinus and Ixodes persulcatus ticks in Finland

Abstract Background Ticks are responsible for transmitting several notable pathogens worldwide. Finland lies in a zone where two human-biting tick species co-occur: Ixodes ricinus and Ixodes persulcatus. Tick densities have increased in boreal regions worldwide during past decades, and tick-borne pa...

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Main Authors: Ruut Uusitalo, Mika Siljander, Andreas Lindén, Jani J. Sormunen, Juha Aalto, Guy Hendrickx, Eva Kallio, Andrea Vajda, Hilppa Gregow, Heikki Henttonen, Cedric Marsboom, Essi M. Korhonen, Tarja Sironen, Petri Pellikka, Olli Vapalahti
Format: Article
Language:English
Published: BMC 2022-08-01
Series:Parasites & Vectors
Subjects:
Online Access:https://doi.org/10.1186/s13071-022-05410-8
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author Ruut Uusitalo
Mika Siljander
Andreas Lindén
Jani J. Sormunen
Juha Aalto
Guy Hendrickx
Eva Kallio
Andrea Vajda
Hilppa Gregow
Heikki Henttonen
Cedric Marsboom
Essi M. Korhonen
Tarja Sironen
Petri Pellikka
Olli Vapalahti
author_facet Ruut Uusitalo
Mika Siljander
Andreas Lindén
Jani J. Sormunen
Juha Aalto
Guy Hendrickx
Eva Kallio
Andrea Vajda
Hilppa Gregow
Heikki Henttonen
Cedric Marsboom
Essi M. Korhonen
Tarja Sironen
Petri Pellikka
Olli Vapalahti
author_sort Ruut Uusitalo
collection DOAJ
description Abstract Background Ticks are responsible for transmitting several notable pathogens worldwide. Finland lies in a zone where two human-biting tick species co-occur: Ixodes ricinus and Ixodes persulcatus. Tick densities have increased in boreal regions worldwide during past decades, and tick-borne pathogens have been identified as one of the major threats to public health in the face of climate change. Methods We used species distribution modelling techniques to predict the distributions of I. ricinus and I. persulcatus, using aggregated historical data from 2014 to 2020 and new tick occurrence data from 2021. By aiming to fill the gaps in tick occurrence data, we created a new sampling strategy across Finland. We also screened for tick-borne encephalitis virus (TBEV) and Borrelia from the newly collected ticks. Climate, land use and vegetation data, and population densities of the tick hosts were used in various combinations on four data sets to estimate tick species’ distributions across mainland Finland with a 1-km resolution. Results In the 2021 survey, 89 new locations were sampled of which 25 new presences and 63 absences were found for I. ricinus and one new presence and 88 absences for I. persulcatus. A total of 502 ticks were collected and analysed; no ticks were positive for TBEV, while 56 (47%) of the 120 pools, including adult, nymph, and larva pools, were positive for Borrelia (minimum infection rate 11.2%, respectively). Our prediction results demonstrate that two combined predictor data sets based on ensemble mean models yielded the highest predictive accuracy for both I. ricinus (AUC = 0.91, 0.94) and I. persulcatus (AUC = 0.93, 0.96). The suitable habitats for I. ricinus were determined by higher relative humidity, air temperature, precipitation sum, and middle-infrared reflectance levels and higher densities of white-tailed deer, European hare, and red fox. For I. persulcatus, locations with greater precipitation and air temperature and higher white-tailed deer, roe deer, and mountain hare densities were associated with higher occurrence probabilities. Suitable habitats for I. ricinus ranged from southern Finland up to Central Ostrobothnia and North Karelia, excluding areas in Ostrobothnia and Pirkanmaa. For I. persulcatus, suitable areas were located along the western coast from Ostrobothnia to southern Lapland, in North Karelia, North Savo, Kainuu, and areas in Pirkanmaa and Päijät-Häme. Conclusions This is the first study conducted in Finland that estimates potential tick species distributions using environmental and host data. Our results can be utilized in vector control strategies, as supporting material in recommendations issued by public health authorities, and as predictor data for modelling the risk for tick-borne diseases.
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spelling doaj.art-7b3ffb43e9164540b34e9655cdeb0ddc2022-12-22T02:19:31ZengBMCParasites & Vectors1756-33052022-08-0115112110.1186/s13071-022-05410-8Predicting habitat suitability for Ixodes ricinus and Ixodes persulcatus ticks in FinlandRuut Uusitalo0Mika Siljander1Andreas Lindén2Jani J. Sormunen3Juha Aalto4Guy Hendrickx5Eva Kallio6Andrea Vajda7Hilppa Gregow8Heikki Henttonen9Cedric Marsboom10Essi M. Korhonen11Tarja Sironen12Petri Pellikka13Olli Vapalahti14Department of Geosciences and Geography, University of HelsinkiDepartment of Geosciences and Geography, University of HelsinkiNatural Resources Institute FinlandBiodiversity Unit, University of TurkuWeather and Climate Change Impact Research Unit, Finnish Meteorological InstituteResearch Department, AVIA-GISDepartment of Biological and Environmental Science and School of Resource Wisdom, University of JyväskyläWeather and Climate Change Impact Research Unit, Finnish Meteorological InstituteWeather and Climate Change Impact Research Unit, Finnish Meteorological InstituteNatural Resources Institute FinlandResearch Department, AVIA-GISDepartment of Virology, University of HelsinkiDepartment of Virology, University of HelsinkiDepartment of Geosciences and Geography, University of HelsinkiDepartment of Virology, University of HelsinkiAbstract Background Ticks are responsible for transmitting several notable pathogens worldwide. Finland lies in a zone where two human-biting tick species co-occur: Ixodes ricinus and Ixodes persulcatus. Tick densities have increased in boreal regions worldwide during past decades, and tick-borne pathogens have been identified as one of the major threats to public health in the face of climate change. Methods We used species distribution modelling techniques to predict the distributions of I. ricinus and I. persulcatus, using aggregated historical data from 2014 to 2020 and new tick occurrence data from 2021. By aiming to fill the gaps in tick occurrence data, we created a new sampling strategy across Finland. We also screened for tick-borne encephalitis virus (TBEV) and Borrelia from the newly collected ticks. Climate, land use and vegetation data, and population densities of the tick hosts were used in various combinations on four data sets to estimate tick species’ distributions across mainland Finland with a 1-km resolution. Results In the 2021 survey, 89 new locations were sampled of which 25 new presences and 63 absences were found for I. ricinus and one new presence and 88 absences for I. persulcatus. A total of 502 ticks were collected and analysed; no ticks were positive for TBEV, while 56 (47%) of the 120 pools, including adult, nymph, and larva pools, were positive for Borrelia (minimum infection rate 11.2%, respectively). Our prediction results demonstrate that two combined predictor data sets based on ensemble mean models yielded the highest predictive accuracy for both I. ricinus (AUC = 0.91, 0.94) and I. persulcatus (AUC = 0.93, 0.96). The suitable habitats for I. ricinus were determined by higher relative humidity, air temperature, precipitation sum, and middle-infrared reflectance levels and higher densities of white-tailed deer, European hare, and red fox. For I. persulcatus, locations with greater precipitation and air temperature and higher white-tailed deer, roe deer, and mountain hare densities were associated with higher occurrence probabilities. Suitable habitats for I. ricinus ranged from southern Finland up to Central Ostrobothnia and North Karelia, excluding areas in Ostrobothnia and Pirkanmaa. For I. persulcatus, suitable areas were located along the western coast from Ostrobothnia to southern Lapland, in North Karelia, North Savo, Kainuu, and areas in Pirkanmaa and Päijät-Häme. Conclusions This is the first study conducted in Finland that estimates potential tick species distributions using environmental and host data. Our results can be utilized in vector control strategies, as supporting material in recommendations issued by public health authorities, and as predictor data for modelling the risk for tick-borne diseases.https://doi.org/10.1186/s13071-022-05410-8Ixodes ricinusIxodes persulcatusSpecies distribution modellingEnsemble predictionTick-borne pathogenBorrelia burgdorferi sensu lato
spellingShingle Ruut Uusitalo
Mika Siljander
Andreas Lindén
Jani J. Sormunen
Juha Aalto
Guy Hendrickx
Eva Kallio
Andrea Vajda
Hilppa Gregow
Heikki Henttonen
Cedric Marsboom
Essi M. Korhonen
Tarja Sironen
Petri Pellikka
Olli Vapalahti
Predicting habitat suitability for Ixodes ricinus and Ixodes persulcatus ticks in Finland
Parasites & Vectors
Ixodes ricinus
Ixodes persulcatus
Species distribution modelling
Ensemble prediction
Tick-borne pathogen
Borrelia burgdorferi sensu lato
title Predicting habitat suitability for Ixodes ricinus and Ixodes persulcatus ticks in Finland
title_full Predicting habitat suitability for Ixodes ricinus and Ixodes persulcatus ticks in Finland
title_fullStr Predicting habitat suitability for Ixodes ricinus and Ixodes persulcatus ticks in Finland
title_full_unstemmed Predicting habitat suitability for Ixodes ricinus and Ixodes persulcatus ticks in Finland
title_short Predicting habitat suitability for Ixodes ricinus and Ixodes persulcatus ticks in Finland
title_sort predicting habitat suitability for ixodes ricinus and ixodes persulcatus ticks in finland
topic Ixodes ricinus
Ixodes persulcatus
Species distribution modelling
Ensemble prediction
Tick-borne pathogen
Borrelia burgdorferi sensu lato
url https://doi.org/10.1186/s13071-022-05410-8
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