Prevalence of tick-borne pathogens in questing Ixodes ricinus ticks in urban and suburban areas of Switzerland

Corinne P Oechslin,Olivier Rais,Christian M Beuret,Stephen L Leib,Daniel Heutschi,Sergei Bankoul,Werner Tischhauser,Rahel Ackermann-Gäumann,Olivier Péter,Nicole Lenz

doi:10.1186/s13071-017-2500-2

Corinne P Oechslin, Olivier Rais + Show 8 more

Open Access

https://doi.org/10.1186/s13071-017-2500-2

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Abstract

BackgroundThroughout Europe, Ixodes ricinus transmits numerous pathogens. Its widespread distribution is not limited to rural but also includes urbanized areas. To date, comprehensive data on pathogen carrier rates of I. ricinus ticks in urban areas of Switzerland is lacking.ResultsIxodes ricinus ticks sampled at 18 (sub-) urban collection sites throughout Switzerland showed carrier rates of 0% for tick-borne encephalitis virus, 18.0% for Borrelia burgdorferi (sensu lato), 2.5% for Borrelia miyamotoi, 13.5% for Rickettsia spp., 1.4% for Anaplasma phagocytophilum, 6.2% for "Candidatus Neoehrlichia mikurensis", and 0.8% for Babesia venatorum (Babesia sp., EU1). Site-specific prevalence at collection sites with n > 45 ticks (n = 9) significantly differed for B. burgdorferi (s.l.), Rickettsia spp., and "Ca. N. mikurensis", but were not related to the habitat type. Three hundred fifty eight out of 1078 I. ricinus ticks (33.2%) tested positive for at least one pathogen. Thereof, about 20% (71/358) were carrying two or three different potentially disease-causing agents. Using next generation sequencing, we could detect true pathogens, tick symbionts and organisms of environmental or human origin in ten selected samples.ConclusionsOur data document the presence of pathogens in the (sub-) urban I. ricinus tick population in Switzerland, with carrier rates as high as those in rural regions. Carriage of multiple pathogens was repeatedly observed, demonstrating the risk of acquiring multiple infections as a consequence of a tick bite.

Highlights

Throughout Europe, Ixodes ricinus transmits numerous pathogens
Pathogen prevalence was not significantly different between collection sites belonging to different habitat types (P-values with Chisquare test using Bonferroni correction > 0.1 for B. burgdorferi (s.l.), B. miyamotoi, A. phagocytophilum and B. venatorum, > 0.05 for "Ca
Studies investigating I. ricinus ticks collected from vegetation or animals in Switzerland revealed Rickettsia spp. carriage rates of 7.3 to 14% [21, 26, 93]. In accordance with these results and with the detection of Rickettsia spp. in urban areas in other studies in Germany and Slovakia at carrier rates ranging between 2.2–30.1% [30, 31, 33, 34], we found R. helvetica-positive I. ricinus ticks at a prevalence of 13.2% in urban areas of Switzerland

Summary

Introduction

Throughout Europe, Ixodes ricinus transmits numerous pathogens. Ixodes ricinus is the most frequent tick species throughout Europe. Ixodes ricinus may act as a parasite on more than 200 different species, including humans. It serves as a vector for numerous human and animal pathogens of bacterial, viral, or protozoic origin [1, 2]. The virus is transmitted transovarially in I. ricinus ticks, this transmission is not effective enough in sustaining viral circulation in nature [7]. In Switzerland, 38/165 rural sites screened for the Oechslin et al Parasites & Vectors (2017) 10:558 presence of TBEV in I. ricinus ticks were shown to harbor natural foci, with a mean virus prevalence of 0.46% [10]

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