Occurrence of tick-borne pathogens in questing Ixodes ricinus ticks from Wester Ross, Northwest Scotland

Jolyon Medlock,Fanny Olsthoorn,Hein Sprong,Manoj Fonville,Mara Rocchi,Jaboury Ghazoul,Lucy Gilbert

doi:10.1186/s13071-021-04946-5

Abstract

BackgroundLyme borreliosis and other tick-borne diseases emerge from increased interactions between humans, other animals, and infected ticks. The risk of acquiring a tick-borne infection varies across space and time, so knowledge of the occurrence and prevalence of pathogens in ticks can facilitate disease diagnosis in a specific area and the implementation of mitigation measures and awareness campaigns. Here we identify the occurrence and prevalence of several pathogens in Ixodes ricinus ticks in Wester Ross, Northwest Scotland, a region of high tourism and tick exposure, yet data-poor in terms of tick-borne pathogens.MethodsQuesting I. ricinus nymphs (n = 2828) were collected from 26 sites in 2018 and 2019 and tested for the presence of tick-borne pathogens using PCR-based methods. Prevalence was compared with other regions of Scotland, England, Wales, and the Netherlands.ResultsAnaplasma phagocytophilum (4.7% prevalence), Borrelia burgdorferi sensu lato (s.l.) (2.2%), Babesia from clade X (0.2%), Rickettsia helvetica (0.04%), and Spiroplasma ixodetis (0.4%) were detected, but no Neoehrlichia mikurensis, Borrelia miyamotoi, or Babesia microti. Typing of A. phagocytophilum using a fragment of the GroEL gene identified the presence of both ecotype I and ecotype II. Genospecies identification of Borrelia burgdorferi s.l. revealed B. afzelii (53% of infected nymphs), B. garinii (9%), B. burgdorferi sensu stricto (7%), and B. valaisiana (31%). We found similar prevalence of A. phagocytophilum in Wester Ross as in the Netherlands, but higher than in other parts of Great Britain. We found lower B. burgdorferi s.l. prevalence than in England or the Netherlands, and similar to some other Scottish studies. We found higher prevalence of B. valaisiana and lower prevalence of B. garinii than in other Scottish studies. We found S. ixodetis at much lower prevalence than in the Netherlands, and R. helvetica at much lower prevalence than in England and the Netherlands.ConclusionsAs far as we know, this is the first description of S. ixodetis in Great Britain. The results are relevant for disease surveillance and management for public and veterinary health. The findings can also aid in designing targeted public health campaigns and in raising awareness among outdoor recreationists and professionals.Graphical abstract

Highlights

Lyme borreliosis and other tick-borne diseases emerge from increased interactions between humans, other animals, and infected ticks
We detected the following pathogens tested in the 2828 questing I. ricinus ticks from Wester Ross, from highest to lowest prevalence: A. phagocytophilum (4.7% prevalence; 132/2828), B. burgdorferi s.l. (2.2%; 63/2828), S. ixodetis (0.4%; 12/2828), Babesia spp. from clade X (0.2%; 5/2828), and R. helvetica (0.04%; 1/2828)
Four genospecies of B. burgdorferi s.l. were detected in the following proportions of positive nymphs: B. afzelii (53%, 24/63), B. valaisiana (31%, 14/63), B. garinii (9%, 4/63), and B. burgdorferi s.s. (7%, 3/63)

Summary

Introduction

Lyme borreliosis and other tick-borne diseases emerge from increased interactions between humans, other animals, and infected ticks. The primary public health concerns are Lyme borreliosis, caused by Borrelia burgdorferi sensu lato (s.l.) infection, and tick-borne encephalitis (TBE), both of which have increased in incidence in several European countries in recent decades [3,4,5,6,7]. Ixodes ricinus transmits other pathogens, including Anaplasma phagocytophilum, Borrelia miyamotoi, Neoehrlichia mikurensis, Rickettsia helvetica, Spiroplasma ixodetis, and several Babesia species. These are currently the key known pathogens that can cause disease in livestock, wild animals, and/or humans [9, 10]. The number of studies describing human infections involving these other tick-borne pathogens is increasing, their incidence is largely unknown, awareness is low, and adequate diagnostic modalities are often lacking in routine settings [10, 11]

Objectives

Methods

Results

Discussion

Conclusion